arm-buildroot-linux-gnueabi/sysroot/usr/share/info/libc.info-7

This is libc.info, produced by makeinfo version 5.2 from libc.texinfo.

This file documents the GNU C Library.

   This is 'The GNU C Library Reference Manual', for version 2.19
(Buildroot).

   Copyright (C) 1993-2014 Free Software Foundation, Inc.

   Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with the
Invariant Sections being "Free Software Needs Free Documentation" and
"GNU Lesser General Public License", the Front-Cover texts being "A GNU
Manual", and with the Back-Cover Texts as in (a) below.  A copy of the
license is included in the section entitled "GNU Free Documentation
License".

   (a) The FSF's Back-Cover Text is: "You have the freedom to copy and
modify this GNU manual.  Buying copies from the FSF supports it in
developing GNU and promoting software freedom."
INFO-DIR-SECTION Software libraries
START-INFO-DIR-ENTRY
* Libc: (libc).                 C library.
END-INFO-DIR-ENTRY

INFO-DIR-SECTION GNU C library functions and macros
START-INFO-DIR-ENTRY
* ALTWERASE: (libc)Local Modes.
* ARGP_ERR_UNKNOWN: (libc)Argp Parser Functions.
* ARG_MAX: (libc)General Limits.
* BC_BASE_MAX: (libc)Utility Limits.
* BC_DIM_MAX: (libc)Utility Limits.
* BC_SCALE_MAX: (libc)Utility Limits.
* BC_STRING_MAX: (libc)Utility Limits.
* BRKINT: (libc)Input Modes.
* BUFSIZ: (libc)Controlling Buffering.
* CCTS_OFLOW: (libc)Control Modes.
* CHILD_MAX: (libc)General Limits.
* CIGNORE: (libc)Control Modes.
* CLK_TCK: (libc)Processor Time.
* CLOCAL: (libc)Control Modes.
* CLOCKS_PER_SEC: (libc)CPU Time.
* COLL_WEIGHTS_MAX: (libc)Utility Limits.
* CPU_CLR: (libc)CPU Affinity.
* CPU_ISSET: (libc)CPU Affinity.
* CPU_SET: (libc)CPU Affinity.
* CPU_SETSIZE: (libc)CPU Affinity.
* CPU_ZERO: (libc)CPU Affinity.
* CREAD: (libc)Control Modes.
* CRTS_IFLOW: (libc)Control Modes.
* CS5: (libc)Control Modes.
* CS6: (libc)Control Modes.
* CS7: (libc)Control Modes.
* CS8: (libc)Control Modes.
* CSIZE: (libc)Control Modes.
* CSTOPB: (libc)Control Modes.
* DES_FAILED: (libc)DES Encryption.
* DTTOIF: (libc)Directory Entries.
* E2BIG: (libc)Error Codes.
* EACCES: (libc)Error Codes.
* EADDRINUSE: (libc)Error Codes.
* EADDRNOTAVAIL: (libc)Error Codes.
* EADV: (libc)Error Codes.
* EAFNOSUPPORT: (libc)Error Codes.
* EAGAIN: (libc)Error Codes.
* EALREADY: (libc)Error Codes.
* EAUTH: (libc)Error Codes.
* EBACKGROUND: (libc)Error Codes.
* EBADE: (libc)Error Codes.
* EBADF: (libc)Error Codes.
* EBADFD: (libc)Error Codes.
* EBADMSG: (libc)Error Codes.
* EBADR: (libc)Error Codes.
* EBADRPC: (libc)Error Codes.
* EBADRQC: (libc)Error Codes.
* EBADSLT: (libc)Error Codes.
* EBFONT: (libc)Error Codes.
* EBUSY: (libc)Error Codes.
* ECANCELED: (libc)Error Codes.
* ECHILD: (libc)Error Codes.
* ECHO: (libc)Local Modes.
* ECHOCTL: (libc)Local Modes.
* ECHOE: (libc)Local Modes.
* ECHOK: (libc)Local Modes.
* ECHOKE: (libc)Local Modes.
* ECHONL: (libc)Local Modes.
* ECHOPRT: (libc)Local Modes.
* ECHRNG: (libc)Error Codes.
* ECOMM: (libc)Error Codes.
* ECONNABORTED: (libc)Error Codes.
* ECONNREFUSED: (libc)Error Codes.
* ECONNRESET: (libc)Error Codes.
* ED: (libc)Error Codes.
* EDEADLK: (libc)Error Codes.
* EDEADLOCK: (libc)Error Codes.
* EDESTADDRREQ: (libc)Error Codes.
* EDIED: (libc)Error Codes.
* EDOM: (libc)Error Codes.
* EDOTDOT: (libc)Error Codes.
* EDQUOT: (libc)Error Codes.
* EEXIST: (libc)Error Codes.
* EFAULT: (libc)Error Codes.
* EFBIG: (libc)Error Codes.
* EFTYPE: (libc)Error Codes.
* EGRATUITOUS: (libc)Error Codes.
* EGREGIOUS: (libc)Error Codes.
* EHOSTDOWN: (libc)Error Codes.
* EHOSTUNREACH: (libc)Error Codes.
* EHWPOISON: (libc)Error Codes.
* EIDRM: (libc)Error Codes.
* EIEIO: (libc)Error Codes.
* EILSEQ: (libc)Error Codes.
* EINPROGRESS: (libc)Error Codes.
* EINTR: (libc)Error Codes.
* EINVAL: (libc)Error Codes.
* EIO: (libc)Error Codes.
* EISCONN: (libc)Error Codes.
* EISDIR: (libc)Error Codes.
* EISNAM: (libc)Error Codes.
* EKEYEXPIRED: (libc)Error Codes.
* EKEYREJECTED: (libc)Error Codes.
* EKEYREVOKED: (libc)Error Codes.
* EL2HLT: (libc)Error Codes.
* EL2NSYNC: (libc)Error Codes.
* EL3HLT: (libc)Error Codes.
* EL3RST: (libc)Error Codes.
* ELIBACC: (libc)Error Codes.
* ELIBBAD: (libc)Error Codes.
* ELIBEXEC: (libc)Error Codes.
* ELIBMAX: (libc)Error Codes.
* ELIBSCN: (libc)Error Codes.
* ELNRNG: (libc)Error Codes.
* ELOOP: (libc)Error Codes.
* EMEDIUMTYPE: (libc)Error Codes.
* EMFILE: (libc)Error Codes.
* EMLINK: (libc)Error Codes.
* EMSGSIZE: (libc)Error Codes.
* EMULTIHOP: (libc)Error Codes.
* ENAMETOOLONG: (libc)Error Codes.
* ENAVAIL: (libc)Error Codes.
* ENEEDAUTH: (libc)Error Codes.
* ENETDOWN: (libc)Error Codes.
* ENETRESET: (libc)Error Codes.
* ENETUNREACH: (libc)Error Codes.
* ENFILE: (libc)Error Codes.
* ENOANO: (libc)Error Codes.
* ENOBUFS: (libc)Error Codes.
* ENOCSI: (libc)Error Codes.
* ENODATA: (libc)Error Codes.
* ENODEV: (libc)Error Codes.
* ENOENT: (libc)Error Codes.
* ENOEXEC: (libc)Error Codes.
* ENOKEY: (libc)Error Codes.
* ENOLCK: (libc)Error Codes.
* ENOLINK: (libc)Error Codes.
* ENOMEDIUM: (libc)Error Codes.
* ENOMEM: (libc)Error Codes.
* ENOMSG: (libc)Error Codes.
* ENONET: (libc)Error Codes.
* ENOPKG: (libc)Error Codes.
* ENOPROTOOPT: (libc)Error Codes.
* ENOSPC: (libc)Error Codes.
* ENOSR: (libc)Error Codes.
* ENOSTR: (libc)Error Codes.
* ENOSYS: (libc)Error Codes.
* ENOTBLK: (libc)Error Codes.
* ENOTCONN: (libc)Error Codes.
* ENOTDIR: (libc)Error Codes.
* ENOTEMPTY: (libc)Error Codes.
* ENOTNAM: (libc)Error Codes.
* ENOTRECOVERABLE: (libc)Error Codes.
* ENOTSOCK: (libc)Error Codes.
* ENOTSUP: (libc)Error Codes.
* ENOTTY: (libc)Error Codes.
* ENOTUNIQ: (libc)Error Codes.
* ENXIO: (libc)Error Codes.
* EOF: (libc)EOF and Errors.
* EOPNOTSUPP: (libc)Error Codes.
* EOVERFLOW: (libc)Error Codes.
* EOWNERDEAD: (libc)Error Codes.
* EPERM: (libc)Error Codes.
* EPFNOSUPPORT: (libc)Error Codes.
* EPIPE: (libc)Error Codes.
* EPROCLIM: (libc)Error Codes.
* EPROCUNAVAIL: (libc)Error Codes.
* EPROGMISMATCH: (libc)Error Codes.
* EPROGUNAVAIL: (libc)Error Codes.
* EPROTO: (libc)Error Codes.
* EPROTONOSUPPORT: (libc)Error Codes.
* EPROTOTYPE: (libc)Error Codes.
* EQUIV_CLASS_MAX: (libc)Utility Limits.
* ERANGE: (libc)Error Codes.
* EREMCHG: (libc)Error Codes.
* EREMOTE: (libc)Error Codes.
* EREMOTEIO: (libc)Error Codes.
* ERESTART: (libc)Error Codes.
* ERFKILL: (libc)Error Codes.
* EROFS: (libc)Error Codes.
* ERPCMISMATCH: (libc)Error Codes.
* ESHUTDOWN: (libc)Error Codes.
* ESOCKTNOSUPPORT: (libc)Error Codes.
* ESPIPE: (libc)Error Codes.
* ESRCH: (libc)Error Codes.
* ESRMNT: (libc)Error Codes.
* ESTALE: (libc)Error Codes.
* ESTRPIPE: (libc)Error Codes.
* ETIME: (libc)Error Codes.
* ETIMEDOUT: (libc)Error Codes.
* ETOOMANYREFS: (libc)Error Codes.
* ETXTBSY: (libc)Error Codes.
* EUCLEAN: (libc)Error Codes.
* EUNATCH: (libc)Error Codes.
* EUSERS: (libc)Error Codes.
* EWOULDBLOCK: (libc)Error Codes.
* EXDEV: (libc)Error Codes.
* EXFULL: (libc)Error Codes.
* EXIT_FAILURE: (libc)Exit Status.
* EXIT_SUCCESS: (libc)Exit Status.
* EXPR_NEST_MAX: (libc)Utility Limits.
* FD_CLOEXEC: (libc)Descriptor Flags.
* FD_CLR: (libc)Waiting for I/O.
* FD_ISSET: (libc)Waiting for I/O.
* FD_SET: (libc)Waiting for I/O.
* FD_SETSIZE: (libc)Waiting for I/O.
* FD_ZERO: (libc)Waiting for I/O.
* FILENAME_MAX: (libc)Limits for Files.
* FLUSHO: (libc)Local Modes.
* FOPEN_MAX: (libc)Opening Streams.
* FP_ILOGB0: (libc)Exponents and Logarithms.
* FP_ILOGBNAN: (libc)Exponents and Logarithms.
* F_DUPFD: (libc)Duplicating Descriptors.
* F_GETFD: (libc)Descriptor Flags.
* F_GETFL: (libc)Getting File Status Flags.
* F_GETLK: (libc)File Locks.
* F_GETOWN: (libc)Interrupt Input.
* F_OK: (libc)Testing File Access.
* F_SETFD: (libc)Descriptor Flags.
* F_SETFL: (libc)Getting File Status Flags.
* F_SETLK: (libc)File Locks.
* F_SETLKW: (libc)File Locks.
* F_SETOWN: (libc)Interrupt Input.
* HUGE_VAL: (libc)Math Error Reporting.
* HUGE_VALF: (libc)Math Error Reporting.
* HUGE_VALL: (libc)Math Error Reporting.
* HUPCL: (libc)Control Modes.
* I: (libc)Complex Numbers.
* ICANON: (libc)Local Modes.
* ICRNL: (libc)Input Modes.
* IEXTEN: (libc)Local Modes.
* IFNAMSIZ: (libc)Interface Naming.
* IFTODT: (libc)Directory Entries.
* IGNBRK: (libc)Input Modes.
* IGNCR: (libc)Input Modes.
* IGNPAR: (libc)Input Modes.
* IMAXBEL: (libc)Input Modes.
* INADDR_ANY: (libc)Host Address Data Type.
* INADDR_BROADCAST: (libc)Host Address Data Type.
* INADDR_LOOPBACK: (libc)Host Address Data Type.
* INADDR_NONE: (libc)Host Address Data Type.
* INFINITY: (libc)Infinity and NaN.
* INLCR: (libc)Input Modes.
* INPCK: (libc)Input Modes.
* IPPORT_RESERVED: (libc)Ports.
* IPPORT_USERRESERVED: (libc)Ports.
* ISIG: (libc)Local Modes.
* ISTRIP: (libc)Input Modes.
* IXANY: (libc)Input Modes.
* IXOFF: (libc)Input Modes.
* IXON: (libc)Input Modes.
* LINE_MAX: (libc)Utility Limits.
* LINK_MAX: (libc)Limits for Files.
* L_ctermid: (libc)Identifying the Terminal.
* L_cuserid: (libc)Who Logged In.
* L_tmpnam: (libc)Temporary Files.
* MAXNAMLEN: (libc)Limits for Files.
* MAXSYMLINKS: (libc)Symbolic Links.
* MAX_CANON: (libc)Limits for Files.
* MAX_INPUT: (libc)Limits for Files.
* MB_CUR_MAX: (libc)Selecting the Conversion.
* MB_LEN_MAX: (libc)Selecting the Conversion.
* MDMBUF: (libc)Control Modes.
* MSG_DONTROUTE: (libc)Socket Data Options.
* MSG_OOB: (libc)Socket Data Options.
* MSG_PEEK: (libc)Socket Data Options.
* NAME_MAX: (libc)Limits for Files.
* NAN: (libc)Infinity and NaN.
* NCCS: (libc)Mode Data Types.
* NGROUPS_MAX: (libc)General Limits.
* NOFLSH: (libc)Local Modes.
* NOKERNINFO: (libc)Local Modes.
* NSIG: (libc)Standard Signals.
* NULL: (libc)Null Pointer Constant.
* ONLCR: (libc)Output Modes.
* ONOEOT: (libc)Output Modes.
* OPEN_MAX: (libc)General Limits.
* OPOST: (libc)Output Modes.
* OXTABS: (libc)Output Modes.
* O_ACCMODE: (libc)Access Modes.
* O_APPEND: (libc)Operating Modes.
* O_ASYNC: (libc)Operating Modes.
* O_CREAT: (libc)Open-time Flags.
* O_EXCL: (libc)Open-time Flags.
* O_EXEC: (libc)Access Modes.
* O_EXLOCK: (libc)Open-time Flags.
* O_FSYNC: (libc)Operating Modes.
* O_IGNORE_CTTY: (libc)Open-time Flags.
* O_NDELAY: (libc)Operating Modes.
* O_NOATIME: (libc)Operating Modes.
* O_NOCTTY: (libc)Open-time Flags.
* O_NOLINK: (libc)Open-time Flags.
* O_NONBLOCK: (libc)Open-time Flags.
* O_NONBLOCK: (libc)Operating Modes.
* O_NOTRANS: (libc)Open-time Flags.
* O_RDONLY: (libc)Access Modes.
* O_RDWR: (libc)Access Modes.
* O_READ: (libc)Access Modes.
* O_SHLOCK: (libc)Open-time Flags.
* O_SYNC: (libc)Operating Modes.
* O_TRUNC: (libc)Open-time Flags.
* O_WRITE: (libc)Access Modes.
* O_WRONLY: (libc)Access Modes.
* PARENB: (libc)Control Modes.
* PARMRK: (libc)Input Modes.
* PARODD: (libc)Control Modes.
* PATH_MAX: (libc)Limits for Files.
* PA_FLAG_MASK: (libc)Parsing a Template String.
* PENDIN: (libc)Local Modes.
* PF_FILE: (libc)Local Namespace Details.
* PF_INET6: (libc)Internet Namespace.
* PF_INET: (libc)Internet Namespace.
* PF_LOCAL: (libc)Local Namespace Details.
* PF_UNIX: (libc)Local Namespace Details.
* PIPE_BUF: (libc)Limits for Files.
* P_tmpdir: (libc)Temporary Files.
* RAND_MAX: (libc)ISO Random.
* RE_DUP_MAX: (libc)General Limits.
* RLIM_INFINITY: (libc)Limits on Resources.
* R_OK: (libc)Testing File Access.
* SA_NOCLDSTOP: (libc)Flags for Sigaction.
* SA_ONSTACK: (libc)Flags for Sigaction.
* SA_RESTART: (libc)Flags for Sigaction.
* SEEK_CUR: (libc)File Positioning.
* SEEK_END: (libc)File Positioning.
* SEEK_SET: (libc)File Positioning.
* SIGABRT: (libc)Program Error Signals.
* SIGALRM: (libc)Alarm Signals.
* SIGBUS: (libc)Program Error Signals.
* SIGCHLD: (libc)Job Control Signals.
* SIGCLD: (libc)Job Control Signals.
* SIGCONT: (libc)Job Control Signals.
* SIGEMT: (libc)Program Error Signals.
* SIGFPE: (libc)Program Error Signals.
* SIGHUP: (libc)Termination Signals.
* SIGILL: (libc)Program Error Signals.
* SIGINFO: (libc)Miscellaneous Signals.
* SIGINT: (libc)Termination Signals.
* SIGIO: (libc)Asynchronous I/O Signals.
* SIGIOT: (libc)Program Error Signals.
* SIGKILL: (libc)Termination Signals.
* SIGLOST: (libc)Operation Error Signals.
* SIGPIPE: (libc)Operation Error Signals.
* SIGPOLL: (libc)Asynchronous I/O Signals.
* SIGPROF: (libc)Alarm Signals.
* SIGQUIT: (libc)Termination Signals.
* SIGSEGV: (libc)Program Error Signals.
* SIGSTOP: (libc)Job Control Signals.
* SIGSYS: (libc)Program Error Signals.
* SIGTERM: (libc)Termination Signals.
* SIGTRAP: (libc)Program Error Signals.
* SIGTSTP: (libc)Job Control Signals.
* SIGTTIN: (libc)Job Control Signals.
* SIGTTOU: (libc)Job Control Signals.
* SIGURG: (libc)Asynchronous I/O Signals.
* SIGUSR1: (libc)Miscellaneous Signals.
* SIGUSR2: (libc)Miscellaneous Signals.
* SIGVTALRM: (libc)Alarm Signals.
* SIGWINCH: (libc)Miscellaneous Signals.
* SIGXCPU: (libc)Operation Error Signals.
* SIGXFSZ: (libc)Operation Error Signals.
* SIG_ERR: (libc)Basic Signal Handling.
* SOCK_DGRAM: (libc)Communication Styles.
* SOCK_RAW: (libc)Communication Styles.
* SOCK_RDM: (libc)Communication Styles.
* SOCK_SEQPACKET: (libc)Communication Styles.
* SOCK_STREAM: (libc)Communication Styles.
* SOL_SOCKET: (libc)Socket-Level Options.
* SSIZE_MAX: (libc)General Limits.
* STREAM_MAX: (libc)General Limits.
* SUN_LEN: (libc)Local Namespace Details.
* SV_INTERRUPT: (libc)BSD Handler.
* SV_ONSTACK: (libc)BSD Handler.
* SV_RESETHAND: (libc)BSD Handler.
* S_IFMT: (libc)Testing File Type.
* S_ISBLK: (libc)Testing File Type.
* S_ISCHR: (libc)Testing File Type.
* S_ISDIR: (libc)Testing File Type.
* S_ISFIFO: (libc)Testing File Type.
* S_ISLNK: (libc)Testing File Type.
* S_ISREG: (libc)Testing File Type.
* S_ISSOCK: (libc)Testing File Type.
* S_TYPEISMQ: (libc)Testing File Type.
* S_TYPEISSEM: (libc)Testing File Type.
* S_TYPEISSHM: (libc)Testing File Type.
* TMP_MAX: (libc)Temporary Files.
* TOSTOP: (libc)Local Modes.
* TZNAME_MAX: (libc)General Limits.
* VDISCARD: (libc)Other Special.
* VDSUSP: (libc)Signal Characters.
* VEOF: (libc)Editing Characters.
* VEOL2: (libc)Editing Characters.
* VEOL: (libc)Editing Characters.
* VERASE: (libc)Editing Characters.
* VINTR: (libc)Signal Characters.
* VKILL: (libc)Editing Characters.
* VLNEXT: (libc)Other Special.
* VMIN: (libc)Noncanonical Input.
* VQUIT: (libc)Signal Characters.
* VREPRINT: (libc)Editing Characters.
* VSTART: (libc)Start/Stop Characters.
* VSTATUS: (libc)Other Special.
* VSTOP: (libc)Start/Stop Characters.
* VSUSP: (libc)Signal Characters.
* VTIME: (libc)Noncanonical Input.
* VWERASE: (libc)Editing Characters.
* WCHAR_MAX: (libc)Extended Char Intro.
* WCHAR_MIN: (libc)Extended Char Intro.
* WCOREDUMP: (libc)Process Completion Status.
* WEOF: (libc)EOF and Errors.
* WEOF: (libc)Extended Char Intro.
* WEXITSTATUS: (libc)Process Completion Status.
* WIFEXITED: (libc)Process Completion Status.
* WIFSIGNALED: (libc)Process Completion Status.
* WIFSTOPPED: (libc)Process Completion Status.
* WSTOPSIG: (libc)Process Completion Status.
* WTERMSIG: (libc)Process Completion Status.
* W_OK: (libc)Testing File Access.
* X_OK: (libc)Testing File Access.
* _Complex_I: (libc)Complex Numbers.
* _Exit: (libc)Termination Internals.
* _IOFBF: (libc)Controlling Buffering.
* _IOLBF: (libc)Controlling Buffering.
* _IONBF: (libc)Controlling Buffering.
* _Imaginary_I: (libc)Complex Numbers.
* _PATH_UTMP: (libc)Manipulating the Database.
* _PATH_WTMP: (libc)Manipulating the Database.
* _POSIX2_C_DEV: (libc)System Options.
* _POSIX2_C_VERSION: (libc)Version Supported.
* _POSIX2_FORT_DEV: (libc)System Options.
* _POSIX2_FORT_RUN: (libc)System Options.
* _POSIX2_LOCALEDEF: (libc)System Options.
* _POSIX2_SW_DEV: (libc)System Options.
* _POSIX_CHOWN_RESTRICTED: (libc)Options for Files.
* _POSIX_JOB_CONTROL: (libc)System Options.
* _POSIX_NO_TRUNC: (libc)Options for Files.
* _POSIX_SAVED_IDS: (libc)System Options.
* _POSIX_VDISABLE: (libc)Options for Files.
* _POSIX_VERSION: (libc)Version Supported.
* __fbufsize: (libc)Controlling Buffering.
* __flbf: (libc)Controlling Buffering.
* __fpending: (libc)Controlling Buffering.
* __fpurge: (libc)Flushing Buffers.
* __freadable: (libc)Opening Streams.
* __freading: (libc)Opening Streams.
* __fsetlocking: (libc)Streams and Threads.
* __fwritable: (libc)Opening Streams.
* __fwriting: (libc)Opening Streams.
* __gconv_end_fct: (libc)glibc iconv Implementation.
* __gconv_fct: (libc)glibc iconv Implementation.
* __gconv_init_fct: (libc)glibc iconv Implementation.
* __ppc_get_timebase: (libc)PowerPC.
* __ppc_get_timebase_freq: (libc)PowerPC.
* __ppc_mdoio: (libc)PowerPC.
* __ppc_mdoom: (libc)PowerPC.
* __ppc_set_ppr_low: (libc)PowerPC.
* __ppc_set_ppr_med: (libc)PowerPC.
* __ppc_set_ppr_med_low: (libc)PowerPC.
* __ppc_yield: (libc)PowerPC.
* __va_copy: (libc)Argument Macros.
* _exit: (libc)Termination Internals.
* _flushlbf: (libc)Flushing Buffers.
* _tolower: (libc)Case Conversion.
* _toupper: (libc)Case Conversion.
* a64l: (libc)Encode Binary Data.
* abort: (libc)Aborting a Program.
* abs: (libc)Absolute Value.
* accept: (libc)Accepting Connections.
* access: (libc)Testing File Access.
* acos: (libc)Inverse Trig Functions.
* acosf: (libc)Inverse Trig Functions.
* acosh: (libc)Hyperbolic Functions.
* acoshf: (libc)Hyperbolic Functions.
* acoshl: (libc)Hyperbolic Functions.
* acosl: (libc)Inverse Trig Functions.
* addmntent: (libc)mtab.
* addseverity: (libc)Adding Severity Classes.
* adjtime: (libc)High-Resolution Calendar.
* adjtimex: (libc)High-Resolution Calendar.
* aio_cancel64: (libc)Cancel AIO Operations.
* aio_cancel: (libc)Cancel AIO Operations.
* aio_error64: (libc)Status of AIO Operations.
* aio_error: (libc)Status of AIO Operations.
* aio_fsync64: (libc)Synchronizing AIO Operations.
* aio_fsync: (libc)Synchronizing AIO Operations.
* aio_init: (libc)Configuration of AIO.
* aio_read64: (libc)Asynchronous Reads/Writes.
* aio_read: (libc)Asynchronous Reads/Writes.
* aio_return64: (libc)Status of AIO Operations.
* aio_return: (libc)Status of AIO Operations.
* aio_suspend64: (libc)Synchronizing AIO Operations.
* aio_suspend: (libc)Synchronizing AIO Operations.
* aio_write64: (libc)Asynchronous Reads/Writes.
* aio_write: (libc)Asynchronous Reads/Writes.
* alarm: (libc)Setting an Alarm.
* aligned_alloc: (libc)Aligned Memory Blocks.
* alloca: (libc)Variable Size Automatic.
* alphasort64: (libc)Scanning Directory Content.
* alphasort: (libc)Scanning Directory Content.
* argp_error: (libc)Argp Helper Functions.
* argp_failure: (libc)Argp Helper Functions.
* argp_help: (libc)Argp Help.
* argp_parse: (libc)Argp.
* argp_state_help: (libc)Argp Helper Functions.
* argp_usage: (libc)Argp Helper Functions.
* argz_add: (libc)Argz Functions.
* argz_add_sep: (libc)Argz Functions.
* argz_append: (libc)Argz Functions.
* argz_count: (libc)Argz Functions.
* argz_create: (libc)Argz Functions.
* argz_create_sep: (libc)Argz Functions.
* argz_delete: (libc)Argz Functions.
* argz_extract: (libc)Argz Functions.
* argz_insert: (libc)Argz Functions.
* argz_next: (libc)Argz Functions.
* argz_replace: (libc)Argz Functions.
* argz_stringify: (libc)Argz Functions.
* asctime: (libc)Formatting Calendar Time.
* asctime_r: (libc)Formatting Calendar Time.
* asin: (libc)Inverse Trig Functions.
* asinf: (libc)Inverse Trig Functions.
* asinh: (libc)Hyperbolic Functions.
* asinhf: (libc)Hyperbolic Functions.
* asinhl: (libc)Hyperbolic Functions.
* asinl: (libc)Inverse Trig Functions.
* asprintf: (libc)Dynamic Output.
* assert: (libc)Consistency Checking.
* assert_perror: (libc)Consistency Checking.
* atan2: (libc)Inverse Trig Functions.
* atan2f: (libc)Inverse Trig Functions.
* atan2l: (libc)Inverse Trig Functions.
* atan: (libc)Inverse Trig Functions.
* atanf: (libc)Inverse Trig Functions.
* atanh: (libc)Hyperbolic Functions.
* atanhf: (libc)Hyperbolic Functions.
* atanhl: (libc)Hyperbolic Functions.
* atanl: (libc)Inverse Trig Functions.
* atexit: (libc)Cleanups on Exit.
* atof: (libc)Parsing of Floats.
* atoi: (libc)Parsing of Integers.
* atol: (libc)Parsing of Integers.
* atoll: (libc)Parsing of Integers.
* backtrace: (libc)Backtraces.
* backtrace_symbols: (libc)Backtraces.
* backtrace_symbols_fd: (libc)Backtraces.
* basename: (libc)Finding Tokens in a String.
* basename: (libc)Finding Tokens in a String.
* bcmp: (libc)String/Array Comparison.
* bcopy: (libc)Copying and Concatenation.
* bind: (libc)Setting Address.
* bind_textdomain_codeset: (libc)Charset conversion in gettext.
* bindtextdomain: (libc)Locating gettext catalog.
* brk: (libc)Resizing the Data Segment.
* bsearch: (libc)Array Search Function.
* btowc: (libc)Converting a Character.
* bzero: (libc)Copying and Concatenation.
* cabs: (libc)Absolute Value.
* cabsf: (libc)Absolute Value.
* cabsl: (libc)Absolute Value.
* cacos: (libc)Inverse Trig Functions.
* cacosf: (libc)Inverse Trig Functions.
* cacosh: (libc)Hyperbolic Functions.
* cacoshf: (libc)Hyperbolic Functions.
* cacoshl: (libc)Hyperbolic Functions.
* cacosl: (libc)Inverse Trig Functions.
* calloc: (libc)Allocating Cleared Space.
* canonicalize_file_name: (libc)Symbolic Links.
* carg: (libc)Operations on Complex.
* cargf: (libc)Operations on Complex.
* cargl: (libc)Operations on Complex.
* casin: (libc)Inverse Trig Functions.
* casinf: (libc)Inverse Trig Functions.
* casinh: (libc)Hyperbolic Functions.
* casinhf: (libc)Hyperbolic Functions.
* casinhl: (libc)Hyperbolic Functions.
* casinl: (libc)Inverse Trig Functions.
* catan: (libc)Inverse Trig Functions.
* catanf: (libc)Inverse Trig Functions.
* catanh: (libc)Hyperbolic Functions.
* catanhf: (libc)Hyperbolic Functions.
* catanhl: (libc)Hyperbolic Functions.
* catanl: (libc)Inverse Trig Functions.
* catclose: (libc)The catgets Functions.
* catgets: (libc)The catgets Functions.
* catopen: (libc)The catgets Functions.
* cbc_crypt: (libc)DES Encryption.
* cbrt: (libc)Exponents and Logarithms.
* cbrtf: (libc)Exponents and Logarithms.
* cbrtl: (libc)Exponents and Logarithms.
* ccos: (libc)Trig Functions.
* ccosf: (libc)Trig Functions.
* ccosh: (libc)Hyperbolic Functions.
* ccoshf: (libc)Hyperbolic Functions.
* ccoshl: (libc)Hyperbolic Functions.
* ccosl: (libc)Trig Functions.
* ceil: (libc)Rounding Functions.
* ceilf: (libc)Rounding Functions.
* ceill: (libc)Rounding Functions.
* cexp: (libc)Exponents and Logarithms.
* cexpf: (libc)Exponents and Logarithms.
* cexpl: (libc)Exponents and Logarithms.
* cfgetispeed: (libc)Line Speed.
* cfgetospeed: (libc)Line Speed.
* cfmakeraw: (libc)Noncanonical Input.
* cfree: (libc)Freeing after Malloc.
* cfsetispeed: (libc)Line Speed.
* cfsetospeed: (libc)Line Speed.
* cfsetspeed: (libc)Line Speed.
* chdir: (libc)Working Directory.
* chmod: (libc)Setting Permissions.
* chown: (libc)File Owner.
* cimag: (libc)Operations on Complex.
* cimagf: (libc)Operations on Complex.
* cimagl: (libc)Operations on Complex.
* clearenv: (libc)Environment Access.
* clearerr: (libc)Error Recovery.
* clearerr_unlocked: (libc)Error Recovery.
* clock: (libc)CPU Time.
* clog10: (libc)Exponents and Logarithms.
* clog10f: (libc)Exponents and Logarithms.
* clog10l: (libc)Exponents and Logarithms.
* clog: (libc)Exponents and Logarithms.
* clogf: (libc)Exponents and Logarithms.
* clogl: (libc)Exponents and Logarithms.
* close: (libc)Opening and Closing Files.
* closedir: (libc)Reading/Closing Directory.
* closelog: (libc)closelog.
* confstr: (libc)String Parameters.
* conj: (libc)Operations on Complex.
* conjf: (libc)Operations on Complex.
* conjl: (libc)Operations on Complex.
* connect: (libc)Connecting.
* copysign: (libc)FP Bit Twiddling.
* copysignf: (libc)FP Bit Twiddling.
* copysignl: (libc)FP Bit Twiddling.
* cos: (libc)Trig Functions.
* cosf: (libc)Trig Functions.
* cosh: (libc)Hyperbolic Functions.
* coshf: (libc)Hyperbolic Functions.
* coshl: (libc)Hyperbolic Functions.
* cosl: (libc)Trig Functions.
* cpow: (libc)Exponents and Logarithms.
* cpowf: (libc)Exponents and Logarithms.
* cpowl: (libc)Exponents and Logarithms.
* cproj: (libc)Operations on Complex.
* cprojf: (libc)Operations on Complex.
* cprojl: (libc)Operations on Complex.
* creal: (libc)Operations on Complex.
* crealf: (libc)Operations on Complex.
* creall: (libc)Operations on Complex.
* creat64: (libc)Opening and Closing Files.
* creat: (libc)Opening and Closing Files.
* crypt: (libc)crypt.
* crypt_r: (libc)crypt.
* csin: (libc)Trig Functions.
* csinf: (libc)Trig Functions.
* csinh: (libc)Hyperbolic Functions.
* csinhf: (libc)Hyperbolic Functions.
* csinhl: (libc)Hyperbolic Functions.
* csinl: (libc)Trig Functions.
* csqrt: (libc)Exponents and Logarithms.
* csqrtf: (libc)Exponents and Logarithms.
* csqrtl: (libc)Exponents and Logarithms.
* ctan: (libc)Trig Functions.
* ctanf: (libc)Trig Functions.
* ctanh: (libc)Hyperbolic Functions.
* ctanhf: (libc)Hyperbolic Functions.
* ctanhl: (libc)Hyperbolic Functions.
* ctanl: (libc)Trig Functions.
* ctermid: (libc)Identifying the Terminal.
* ctime: (libc)Formatting Calendar Time.
* ctime_r: (libc)Formatting Calendar Time.
* cuserid: (libc)Who Logged In.
* dcgettext: (libc)Translation with gettext.
* dcngettext: (libc)Advanced gettext functions.
* des_setparity: (libc)DES Encryption.
* dgettext: (libc)Translation with gettext.
* difftime: (libc)Elapsed Time.
* dirfd: (libc)Opening a Directory.
* dirname: (libc)Finding Tokens in a String.
* div: (libc)Integer Division.
* dngettext: (libc)Advanced gettext functions.
* drand48: (libc)SVID Random.
* drand48_r: (libc)SVID Random.
* drem: (libc)Remainder Functions.
* dremf: (libc)Remainder Functions.
* dreml: (libc)Remainder Functions.
* dup2: (libc)Duplicating Descriptors.
* dup: (libc)Duplicating Descriptors.
* ecb_crypt: (libc)DES Encryption.
* ecvt: (libc)System V Number Conversion.
* ecvt_r: (libc)System V Number Conversion.
* encrypt: (libc)DES Encryption.
* encrypt_r: (libc)DES Encryption.
* endfsent: (libc)fstab.
* endgrent: (libc)Scanning All Groups.
* endhostent: (libc)Host Names.
* endmntent: (libc)mtab.
* endnetent: (libc)Networks Database.
* endnetgrent: (libc)Lookup Netgroup.
* endprotoent: (libc)Protocols Database.
* endpwent: (libc)Scanning All Users.
* endservent: (libc)Services Database.
* endutent: (libc)Manipulating the Database.
* endutxent: (libc)XPG Functions.
* envz_add: (libc)Envz Functions.
* envz_entry: (libc)Envz Functions.
* envz_get: (libc)Envz Functions.
* envz_merge: (libc)Envz Functions.
* envz_strip: (libc)Envz Functions.
* erand48: (libc)SVID Random.
* erand48_r: (libc)SVID Random.
* erf: (libc)Special Functions.
* erfc: (libc)Special Functions.
* erfcf: (libc)Special Functions.
* erfcl: (libc)Special Functions.
* erff: (libc)Special Functions.
* erfl: (libc)Special Functions.
* err: (libc)Error Messages.
* errno: (libc)Checking for Errors.
* error: (libc)Error Messages.
* error_at_line: (libc)Error Messages.
* errx: (libc)Error Messages.
* execl: (libc)Executing a File.
* execle: (libc)Executing a File.
* execlp: (libc)Executing a File.
* execv: (libc)Executing a File.
* execve: (libc)Executing a File.
* execvp: (libc)Executing a File.
* exit: (libc)Normal Termination.
* exp10: (libc)Exponents and Logarithms.
* exp10f: (libc)Exponents and Logarithms.
* exp10l: (libc)Exponents and Logarithms.
* exp2: (libc)Exponents and Logarithms.
* exp2f: (libc)Exponents and Logarithms.
* exp2l: (libc)Exponents and Logarithms.
* exp: (libc)Exponents and Logarithms.
* expf: (libc)Exponents and Logarithms.
* expl: (libc)Exponents and Logarithms.
* expm1: (libc)Exponents and Logarithms.
* expm1f: (libc)Exponents and Logarithms.
* expm1l: (libc)Exponents and Logarithms.
* fabs: (libc)Absolute Value.
* fabsf: (libc)Absolute Value.
* fabsl: (libc)Absolute Value.
* fchdir: (libc)Working Directory.
* fchmod: (libc)Setting Permissions.
* fchown: (libc)File Owner.
* fclose: (libc)Closing Streams.
* fcloseall: (libc)Closing Streams.
* fcntl: (libc)Control Operations.
* fcvt: (libc)System V Number Conversion.
* fcvt_r: (libc)System V Number Conversion.
* fdatasync: (libc)Synchronizing I/O.
* fdim: (libc)Misc FP Arithmetic.
* fdimf: (libc)Misc FP Arithmetic.
* fdiml: (libc)Misc FP Arithmetic.
* fdopen: (libc)Descriptors and Streams.
* fdopendir: (libc)Opening a Directory.
* feclearexcept: (libc)Status bit operations.
* fedisableexcept: (libc)Control Functions.
* feenableexcept: (libc)Control Functions.
* fegetenv: (libc)Control Functions.
* fegetexcept: (libc)Control Functions.
* fegetexceptflag: (libc)Status bit operations.
* fegetround: (libc)Rounding.
* feholdexcept: (libc)Control Functions.
* feof: (libc)EOF and Errors.
* feof_unlocked: (libc)EOF and Errors.
* feraiseexcept: (libc)Status bit operations.
* ferror: (libc)EOF and Errors.
* ferror_unlocked: (libc)EOF and Errors.
* fesetenv: (libc)Control Functions.
* fesetexceptflag: (libc)Status bit operations.
* fesetround: (libc)Rounding.
* fetestexcept: (libc)Status bit operations.
* feupdateenv: (libc)Control Functions.
* fflush: (libc)Flushing Buffers.
* fflush_unlocked: (libc)Flushing Buffers.
* fgetc: (libc)Character Input.
* fgetc_unlocked: (libc)Character Input.
* fgetgrent: (libc)Scanning All Groups.
* fgetgrent_r: (libc)Scanning All Groups.
* fgetpos64: (libc)Portable Positioning.
* fgetpos: (libc)Portable Positioning.
* fgetpwent: (libc)Scanning All Users.
* fgetpwent_r: (libc)Scanning All Users.
* fgets: (libc)Line Input.
* fgets_unlocked: (libc)Line Input.
* fgetwc: (libc)Character Input.
* fgetwc_unlocked: (libc)Character Input.
* fgetws: (libc)Line Input.
* fgetws_unlocked: (libc)Line Input.
* fileno: (libc)Descriptors and Streams.
* fileno_unlocked: (libc)Descriptors and Streams.
* finite: (libc)Floating Point Classes.
* finitef: (libc)Floating Point Classes.
* finitel: (libc)Floating Point Classes.
* flockfile: (libc)Streams and Threads.
* floor: (libc)Rounding Functions.
* floorf: (libc)Rounding Functions.
* floorl: (libc)Rounding Functions.
* fma: (libc)Misc FP Arithmetic.
* fmaf: (libc)Misc FP Arithmetic.
* fmal: (libc)Misc FP Arithmetic.
* fmax: (libc)Misc FP Arithmetic.
* fmaxf: (libc)Misc FP Arithmetic.
* fmaxl: (libc)Misc FP Arithmetic.
* fmemopen: (libc)String Streams.
* fmin: (libc)Misc FP Arithmetic.
* fminf: (libc)Misc FP Arithmetic.
* fminl: (libc)Misc FP Arithmetic.
* fmod: (libc)Remainder Functions.
* fmodf: (libc)Remainder Functions.
* fmodl: (libc)Remainder Functions.
* fmtmsg: (libc)Printing Formatted Messages.
* fnmatch: (libc)Wildcard Matching.
* fopen64: (libc)Opening Streams.
* fopen: (libc)Opening Streams.
* fopencookie: (libc)Streams and Cookies.
* fork: (libc)Creating a Process.
* forkpty: (libc)Pseudo-Terminal Pairs.
* fpathconf: (libc)Pathconf.
* fpclassify: (libc)Floating Point Classes.
* fprintf: (libc)Formatted Output Functions.
* fputc: (libc)Simple Output.
* fputc_unlocked: (libc)Simple Output.
* fputs: (libc)Simple Output.
* fputs_unlocked: (libc)Simple Output.
* fputwc: (libc)Simple Output.
* fputwc_unlocked: (libc)Simple Output.
* fputws: (libc)Simple Output.
* fputws_unlocked: (libc)Simple Output.
* fread: (libc)Block Input/Output.
* fread_unlocked: (libc)Block Input/Output.
* free: (libc)Freeing after Malloc.
* freopen64: (libc)Opening Streams.
* freopen: (libc)Opening Streams.
* frexp: (libc)Normalization Functions.
* frexpf: (libc)Normalization Functions.
* frexpl: (libc)Normalization Functions.
* fscanf: (libc)Formatted Input Functions.
* fseek: (libc)File Positioning.
* fseeko64: (libc)File Positioning.
* fseeko: (libc)File Positioning.
* fsetpos64: (libc)Portable Positioning.
* fsetpos: (libc)Portable Positioning.
* fstat64: (libc)Reading Attributes.
* fstat: (libc)Reading Attributes.
* fsync: (libc)Synchronizing I/O.
* ftell: (libc)File Positioning.
* ftello64: (libc)File Positioning.
* ftello: (libc)File Positioning.
* ftruncate64: (libc)File Size.
* ftruncate: (libc)File Size.
* ftrylockfile: (libc)Streams and Threads.
* ftw64: (libc)Working with Directory Trees.
* ftw: (libc)Working with Directory Trees.
* funlockfile: (libc)Streams and Threads.
* futimes: (libc)File Times.
* fwide: (libc)Streams and I18N.
* fwprintf: (libc)Formatted Output Functions.
* fwrite: (libc)Block Input/Output.
* fwrite_unlocked: (libc)Block Input/Output.
* fwscanf: (libc)Formatted Input Functions.
* gamma: (libc)Special Functions.
* gammaf: (libc)Special Functions.
* gammal: (libc)Special Functions.
* gcvt: (libc)System V Number Conversion.
* get_avphys_pages: (libc)Query Memory Parameters.
* get_current_dir_name: (libc)Working Directory.
* get_nprocs: (libc)Processor Resources.
* get_nprocs_conf: (libc)Processor Resources.
* get_phys_pages: (libc)Query Memory Parameters.
* getauxval: (libc)Auxiliary Vector.
* getc: (libc)Character Input.
* getc_unlocked: (libc)Character Input.
* getchar: (libc)Character Input.
* getchar_unlocked: (libc)Character Input.
* getcontext: (libc)System V contexts.
* getcwd: (libc)Working Directory.
* getdate: (libc)General Time String Parsing.
* getdate_r: (libc)General Time String Parsing.
* getdelim: (libc)Line Input.
* getdomainnname: (libc)Host Identification.
* getegid: (libc)Reading Persona.
* getenv: (libc)Environment Access.
* geteuid: (libc)Reading Persona.
* getfsent: (libc)fstab.
* getfsfile: (libc)fstab.
* getfsspec: (libc)fstab.
* getgid: (libc)Reading Persona.
* getgrent: (libc)Scanning All Groups.
* getgrent_r: (libc)Scanning All Groups.
* getgrgid: (libc)Lookup Group.
* getgrgid_r: (libc)Lookup Group.
* getgrnam: (libc)Lookup Group.
* getgrnam_r: (libc)Lookup Group.
* getgrouplist: (libc)Setting Groups.
* getgroups: (libc)Reading Persona.
* gethostbyaddr: (libc)Host Names.
* gethostbyaddr_r: (libc)Host Names.
* gethostbyname2: (libc)Host Names.
* gethostbyname2_r: (libc)Host Names.
* gethostbyname: (libc)Host Names.
* gethostbyname_r: (libc)Host Names.
* gethostent: (libc)Host Names.
* gethostid: (libc)Host Identification.
* gethostname: (libc)Host Identification.
* getitimer: (libc)Setting an Alarm.
* getline: (libc)Line Input.
* getloadavg: (libc)Processor Resources.
* getlogin: (libc)Who Logged In.
* getmntent: (libc)mtab.
* getmntent_r: (libc)mtab.
* getnetbyaddr: (libc)Networks Database.
* getnetbyname: (libc)Networks Database.
* getnetent: (libc)Networks Database.
* getnetgrent: (libc)Lookup Netgroup.
* getnetgrent_r: (libc)Lookup Netgroup.
* getopt: (libc)Using Getopt.
* getopt_long: (libc)Getopt Long Options.
* getopt_long_only: (libc)Getopt Long Options.
* getpagesize: (libc)Query Memory Parameters.
* getpass: (libc)getpass.
* getpeername: (libc)Who is Connected.
* getpgid: (libc)Process Group Functions.
* getpgrp: (libc)Process Group Functions.
* getpid: (libc)Process Identification.
* getppid: (libc)Process Identification.
* getpriority: (libc)Traditional Scheduling Functions.
* getprotobyname: (libc)Protocols Database.
* getprotobynumber: (libc)Protocols Database.
* getprotoent: (libc)Protocols Database.
* getpt: (libc)Allocation.
* getpwent: (libc)Scanning All Users.
* getpwent_r: (libc)Scanning All Users.
* getpwnam: (libc)Lookup User.
* getpwnam_r: (libc)Lookup User.
* getpwuid: (libc)Lookup User.
* getpwuid_r: (libc)Lookup User.
* getrlimit64: (libc)Limits on Resources.
* getrlimit: (libc)Limits on Resources.
* getrusage: (libc)Resource Usage.
* gets: (libc)Line Input.
* getservbyname: (libc)Services Database.
* getservbyport: (libc)Services Database.
* getservent: (libc)Services Database.
* getsid: (libc)Process Group Functions.
* getsockname: (libc)Reading Address.
* getsockopt: (libc)Socket Option Functions.
* getsubopt: (libc)Suboptions.
* gettext: (libc)Translation with gettext.
* gettimeofday: (libc)High-Resolution Calendar.
* getuid: (libc)Reading Persona.
* getumask: (libc)Setting Permissions.
* getutent: (libc)Manipulating the Database.
* getutent_r: (libc)Manipulating the Database.
* getutid: (libc)Manipulating the Database.
* getutid_r: (libc)Manipulating the Database.
* getutline: (libc)Manipulating the Database.
* getutline_r: (libc)Manipulating the Database.
* getutmp: (libc)XPG Functions.
* getutmpx: (libc)XPG Functions.
* getutxent: (libc)XPG Functions.
* getutxid: (libc)XPG Functions.
* getutxline: (libc)XPG Functions.
* getw: (libc)Character Input.
* getwc: (libc)Character Input.
* getwc_unlocked: (libc)Character Input.
* getwchar: (libc)Character Input.
* getwchar_unlocked: (libc)Character Input.
* getwd: (libc)Working Directory.
* glob64: (libc)Calling Glob.
* glob: (libc)Calling Glob.
* globfree64: (libc)More Flags for Globbing.
* globfree: (libc)More Flags for Globbing.
* gmtime: (libc)Broken-down Time.
* gmtime_r: (libc)Broken-down Time.
* grantpt: (libc)Allocation.
* gsignal: (libc)Signaling Yourself.
* gtty: (libc)BSD Terminal Modes.
* hasmntopt: (libc)mtab.
* hcreate: (libc)Hash Search Function.
* hcreate_r: (libc)Hash Search Function.
* hdestroy: (libc)Hash Search Function.
* hdestroy_r: (libc)Hash Search Function.
* hsearch: (libc)Hash Search Function.
* hsearch_r: (libc)Hash Search Function.
* htonl: (libc)Byte Order.
* htons: (libc)Byte Order.
* hypot: (libc)Exponents and Logarithms.
* hypotf: (libc)Exponents and Logarithms.
* hypotl: (libc)Exponents and Logarithms.
* iconv: (libc)Generic Conversion Interface.
* iconv_close: (libc)Generic Conversion Interface.
* iconv_open: (libc)Generic Conversion Interface.
* if_freenameindex: (libc)Interface Naming.
* if_indextoname: (libc)Interface Naming.
* if_nameindex: (libc)Interface Naming.
* if_nametoindex: (libc)Interface Naming.
* ilogb: (libc)Exponents and Logarithms.
* ilogbf: (libc)Exponents and Logarithms.
* ilogbl: (libc)Exponents and Logarithms.
* imaxabs: (libc)Absolute Value.
* imaxdiv: (libc)Integer Division.
* in6addr_any: (libc)Host Address Data Type.
* in6addr_loopback: (libc)Host Address Data Type.
* index: (libc)Search Functions.
* inet_addr: (libc)Host Address Functions.
* inet_aton: (libc)Host Address Functions.
* inet_lnaof: (libc)Host Address Functions.
* inet_makeaddr: (libc)Host Address Functions.
* inet_netof: (libc)Host Address Functions.
* inet_network: (libc)Host Address Functions.
* inet_ntoa: (libc)Host Address Functions.
* inet_ntop: (libc)Host Address Functions.
* inet_pton: (libc)Host Address Functions.
* initgroups: (libc)Setting Groups.
* initstate: (libc)BSD Random.
* initstate_r: (libc)BSD Random.
* innetgr: (libc)Netgroup Membership.
* ioctl: (libc)IOCTLs.
* isalnum: (libc)Classification of Characters.
* isalpha: (libc)Classification of Characters.
* isascii: (libc)Classification of Characters.
* isatty: (libc)Is It a Terminal.
* isblank: (libc)Classification of Characters.
* iscntrl: (libc)Classification of Characters.
* isdigit: (libc)Classification of Characters.
* isfinite: (libc)Floating Point Classes.
* isgraph: (libc)Classification of Characters.
* isgreater: (libc)FP Comparison Functions.
* isgreaterequal: (libc)FP Comparison Functions.
* isinf: (libc)Floating Point Classes.
* isinff: (libc)Floating Point Classes.
* isinfl: (libc)Floating Point Classes.
* isless: (libc)FP Comparison Functions.
* islessequal: (libc)FP Comparison Functions.
* islessgreater: (libc)FP Comparison Functions.
* islower: (libc)Classification of Characters.
* isnan: (libc)Floating Point Classes.
* isnan: (libc)Floating Point Classes.
* isnanf: (libc)Floating Point Classes.
* isnanl: (libc)Floating Point Classes.
* isnormal: (libc)Floating Point Classes.
* isprint: (libc)Classification of Characters.
* ispunct: (libc)Classification of Characters.
* issignaling: (libc)Floating Point Classes.
* isspace: (libc)Classification of Characters.
* isunordered: (libc)FP Comparison Functions.
* isupper: (libc)Classification of Characters.
* iswalnum: (libc)Classification of Wide Characters.
* iswalpha: (libc)Classification of Wide Characters.
* iswblank: (libc)Classification of Wide Characters.
* iswcntrl: (libc)Classification of Wide Characters.
* iswctype: (libc)Classification of Wide Characters.
* iswdigit: (libc)Classification of Wide Characters.
* iswgraph: (libc)Classification of Wide Characters.
* iswlower: (libc)Classification of Wide Characters.
* iswprint: (libc)Classification of Wide Characters.
* iswpunct: (libc)Classification of Wide Characters.
* iswspace: (libc)Classification of Wide Characters.
* iswupper: (libc)Classification of Wide Characters.
* iswxdigit: (libc)Classification of Wide Characters.
* isxdigit: (libc)Classification of Characters.
* j0: (libc)Special Functions.
* j0f: (libc)Special Functions.
* j0l: (libc)Special Functions.
* j1: (libc)Special Functions.
* j1f: (libc)Special Functions.
* j1l: (libc)Special Functions.
* jn: (libc)Special Functions.
* jnf: (libc)Special Functions.
* jnl: (libc)Special Functions.
* jrand48: (libc)SVID Random.
* jrand48_r: (libc)SVID Random.
* kill: (libc)Signaling Another Process.
* killpg: (libc)Signaling Another Process.
* l64a: (libc)Encode Binary Data.
* labs: (libc)Absolute Value.
* lcong48: (libc)SVID Random.
* lcong48_r: (libc)SVID Random.
* ldexp: (libc)Normalization Functions.
* ldexpf: (libc)Normalization Functions.
* ldexpl: (libc)Normalization Functions.
* ldiv: (libc)Integer Division.
* lfind: (libc)Array Search Function.
* lgamma: (libc)Special Functions.
* lgamma_r: (libc)Special Functions.
* lgammaf: (libc)Special Functions.
* lgammaf_r: (libc)Special Functions.
* lgammal: (libc)Special Functions.
* lgammal_r: (libc)Special Functions.
* link: (libc)Hard Links.
* lio_listio64: (libc)Asynchronous Reads/Writes.
* lio_listio: (libc)Asynchronous Reads/Writes.
* listen: (libc)Listening.
* llabs: (libc)Absolute Value.
* lldiv: (libc)Integer Division.
* llrint: (libc)Rounding Functions.
* llrintf: (libc)Rounding Functions.
* llrintl: (libc)Rounding Functions.
* llround: (libc)Rounding Functions.
* llroundf: (libc)Rounding Functions.
* llroundl: (libc)Rounding Functions.
* localeconv: (libc)The Lame Way to Locale Data.
* localtime: (libc)Broken-down Time.
* localtime_r: (libc)Broken-down Time.
* log10: (libc)Exponents and Logarithms.
* log10f: (libc)Exponents and Logarithms.
* log10l: (libc)Exponents and Logarithms.
* log1p: (libc)Exponents and Logarithms.
* log1pf: (libc)Exponents and Logarithms.
* log1pl: (libc)Exponents and Logarithms.
* log2: (libc)Exponents and Logarithms.
* log2f: (libc)Exponents and Logarithms.
* log2l: (libc)Exponents and Logarithms.
* log: (libc)Exponents and Logarithms.
* logb: (libc)Exponents and Logarithms.
* logbf: (libc)Exponents and Logarithms.
* logbl: (libc)Exponents and Logarithms.
* logf: (libc)Exponents and Logarithms.
* login: (libc)Logging In and Out.
* login_tty: (libc)Logging In and Out.
* logl: (libc)Exponents and Logarithms.
* logout: (libc)Logging In and Out.
* logwtmp: (libc)Logging In and Out.
* longjmp: (libc)Non-Local Details.
* lrand48: (libc)SVID Random.
* lrand48_r: (libc)SVID Random.
* lrint: (libc)Rounding Functions.
* lrintf: (libc)Rounding Functions.
* lrintl: (libc)Rounding Functions.
* lround: (libc)Rounding Functions.
* lroundf: (libc)Rounding Functions.
* lroundl: (libc)Rounding Functions.
* lsearch: (libc)Array Search Function.
* lseek64: (libc)File Position Primitive.
* lseek: (libc)File Position Primitive.
* lstat64: (libc)Reading Attributes.
* lstat: (libc)Reading Attributes.
* lutimes: (libc)File Times.
* madvise: (libc)Memory-mapped I/O.
* makecontext: (libc)System V contexts.
* mallinfo: (libc)Statistics of Malloc.
* malloc: (libc)Basic Allocation.
* mallopt: (libc)Malloc Tunable Parameters.
* mblen: (libc)Non-reentrant Character Conversion.
* mbrlen: (libc)Converting a Character.
* mbrtowc: (libc)Converting a Character.
* mbsinit: (libc)Keeping the state.
* mbsnrtowcs: (libc)Converting Strings.
* mbsrtowcs: (libc)Converting Strings.
* mbstowcs: (libc)Non-reentrant String Conversion.
* mbtowc: (libc)Non-reentrant Character Conversion.
* mcheck: (libc)Heap Consistency Checking.
* memalign: (libc)Aligned Memory Blocks.
* memccpy: (libc)Copying and Concatenation.
* memchr: (libc)Search Functions.
* memcmp: (libc)String/Array Comparison.
* memcpy: (libc)Copying and Concatenation.
* memfrob: (libc)Trivial Encryption.
* memmem: (libc)Search Functions.
* memmove: (libc)Copying and Concatenation.
* mempcpy: (libc)Copying and Concatenation.
* memrchr: (libc)Search Functions.
* memset: (libc)Copying and Concatenation.
* mkdir: (libc)Creating Directories.
* mkdtemp: (libc)Temporary Files.
* mkfifo: (libc)FIFO Special Files.
* mknod: (libc)Making Special Files.
* mkstemp: (libc)Temporary Files.
* mktemp: (libc)Temporary Files.
* mktime: (libc)Broken-down Time.
* mlock: (libc)Page Lock Functions.
* mlockall: (libc)Page Lock Functions.
* mmap64: (libc)Memory-mapped I/O.
* mmap: (libc)Memory-mapped I/O.
* modf: (libc)Rounding Functions.
* modff: (libc)Rounding Functions.
* modfl: (libc)Rounding Functions.
* mount: (libc)Mount-Unmount-Remount.
* mprobe: (libc)Heap Consistency Checking.
* mrand48: (libc)SVID Random.
* mrand48_r: (libc)SVID Random.
* mremap: (libc)Memory-mapped I/O.
* msync: (libc)Memory-mapped I/O.
* mtrace: (libc)Tracing malloc.
* munlock: (libc)Page Lock Functions.
* munlockall: (libc)Page Lock Functions.
* munmap: (libc)Memory-mapped I/O.
* muntrace: (libc)Tracing malloc.
* nan: (libc)FP Bit Twiddling.
* nanf: (libc)FP Bit Twiddling.
* nanl: (libc)FP Bit Twiddling.
* nanosleep: (libc)Sleeping.
* nearbyint: (libc)Rounding Functions.
* nearbyintf: (libc)Rounding Functions.
* nearbyintl: (libc)Rounding Functions.
* nextafter: (libc)FP Bit Twiddling.
* nextafterf: (libc)FP Bit Twiddling.
* nextafterl: (libc)FP Bit Twiddling.
* nexttoward: (libc)FP Bit Twiddling.
* nexttowardf: (libc)FP Bit Twiddling.
* nexttowardl: (libc)FP Bit Twiddling.
* nftw64: (libc)Working with Directory Trees.
* nftw: (libc)Working with Directory Trees.
* ngettext: (libc)Advanced gettext functions.
* nice: (libc)Traditional Scheduling Functions.
* nl_langinfo: (libc)The Elegant and Fast Way.
* nrand48: (libc)SVID Random.
* nrand48_r: (libc)SVID Random.
* ntohl: (libc)Byte Order.
* ntohs: (libc)Byte Order.
* ntp_adjtime: (libc)High Accuracy Clock.
* ntp_gettime: (libc)High Accuracy Clock.
* obstack_1grow: (libc)Growing Objects.
* obstack_1grow_fast: (libc)Extra Fast Growing.
* obstack_alignment_mask: (libc)Obstacks Data Alignment.
* obstack_alloc: (libc)Allocation in an Obstack.
* obstack_base: (libc)Status of an Obstack.
* obstack_blank: (libc)Growing Objects.
* obstack_blank_fast: (libc)Extra Fast Growing.
* obstack_chunk_size: (libc)Obstack Chunks.
* obstack_copy0: (libc)Allocation in an Obstack.
* obstack_copy: (libc)Allocation in an Obstack.
* obstack_finish: (libc)Growing Objects.
* obstack_free: (libc)Freeing Obstack Objects.
* obstack_grow0: (libc)Growing Objects.
* obstack_grow: (libc)Growing Objects.
* obstack_init: (libc)Preparing for Obstacks.
* obstack_int_grow: (libc)Growing Objects.
* obstack_int_grow_fast: (libc)Extra Fast Growing.
* obstack_next_free: (libc)Status of an Obstack.
* obstack_object_size: (libc)Growing Objects.
* obstack_object_size: (libc)Status of an Obstack.
* obstack_printf: (libc)Dynamic Output.
* obstack_ptr_grow: (libc)Growing Objects.
* obstack_ptr_grow_fast: (libc)Extra Fast Growing.
* obstack_room: (libc)Extra Fast Growing.
* obstack_vprintf: (libc)Variable Arguments Output.
* offsetof: (libc)Structure Measurement.
* on_exit: (libc)Cleanups on Exit.
* open64: (libc)Opening and Closing Files.
* open: (libc)Opening and Closing Files.
* open_memstream: (libc)String Streams.
* opendir: (libc)Opening a Directory.
* openlog: (libc)openlog.
* openpty: (libc)Pseudo-Terminal Pairs.
* parse_printf_format: (libc)Parsing a Template String.
* pathconf: (libc)Pathconf.
* pause: (libc)Using Pause.
* pclose: (libc)Pipe to a Subprocess.
* perror: (libc)Error Messages.
* pipe: (libc)Creating a Pipe.
* popen: (libc)Pipe to a Subprocess.
* posix_memalign: (libc)Aligned Memory Blocks.
* pow10: (libc)Exponents and Logarithms.
* pow10f: (libc)Exponents and Logarithms.
* pow10l: (libc)Exponents and Logarithms.
* pow: (libc)Exponents and Logarithms.
* powf: (libc)Exponents and Logarithms.
* powl: (libc)Exponents and Logarithms.
* pread64: (libc)I/O Primitives.
* pread: (libc)I/O Primitives.
* printf: (libc)Formatted Output Functions.
* printf_size: (libc)Predefined Printf Handlers.
* printf_size_info: (libc)Predefined Printf Handlers.
* psignal: (libc)Signal Messages.
* pthread_getattr_default_np: (libc)Default Thread Attributes.
* pthread_getspecific: (libc)Thread-specific Data.
* pthread_key_create: (libc)Thread-specific Data.
* pthread_key_delete: (libc)Thread-specific Data.
* pthread_setattr_default_np: (libc)Default Thread Attributes.
* pthread_setspecific: (libc)Thread-specific Data.
* ptsname: (libc)Allocation.
* ptsname_r: (libc)Allocation.
* putc: (libc)Simple Output.
* putc_unlocked: (libc)Simple Output.
* putchar: (libc)Simple Output.
* putchar_unlocked: (libc)Simple Output.
* putenv: (libc)Environment Access.
* putpwent: (libc)Writing a User Entry.
* puts: (libc)Simple Output.
* pututline: (libc)Manipulating the Database.
* pututxline: (libc)XPG Functions.
* putw: (libc)Simple Output.
* putwc: (libc)Simple Output.
* putwc_unlocked: (libc)Simple Output.
* putwchar: (libc)Simple Output.
* putwchar_unlocked: (libc)Simple Output.
* pwrite64: (libc)I/O Primitives.
* pwrite: (libc)I/O Primitives.
* qecvt: (libc)System V Number Conversion.
* qecvt_r: (libc)System V Number Conversion.
* qfcvt: (libc)System V Number Conversion.
* qfcvt_r: (libc)System V Number Conversion.
* qgcvt: (libc)System V Number Conversion.
* qsort: (libc)Array Sort Function.
* raise: (libc)Signaling Yourself.
* rand: (libc)ISO Random.
* rand_r: (libc)ISO Random.
* random: (libc)BSD Random.
* random_r: (libc)BSD Random.
* rawmemchr: (libc)Search Functions.
* read: (libc)I/O Primitives.
* readdir64: (libc)Reading/Closing Directory.
* readdir64_r: (libc)Reading/Closing Directory.
* readdir: (libc)Reading/Closing Directory.
* readdir_r: (libc)Reading/Closing Directory.
* readlink: (libc)Symbolic Links.
* readv: (libc)Scatter-Gather.
* realloc: (libc)Changing Block Size.
* realpath: (libc)Symbolic Links.
* recv: (libc)Receiving Data.
* recvfrom: (libc)Receiving Datagrams.
* recvmsg: (libc)Receiving Datagrams.
* regcomp: (libc)POSIX Regexp Compilation.
* regerror: (libc)Regexp Cleanup.
* regexec: (libc)Matching POSIX Regexps.
* regfree: (libc)Regexp Cleanup.
* register_printf_function: (libc)Registering New Conversions.
* remainder: (libc)Remainder Functions.
* remainderf: (libc)Remainder Functions.
* remainderl: (libc)Remainder Functions.
* remove: (libc)Deleting Files.
* rename: (libc)Renaming Files.
* rewind: (libc)File Positioning.
* rewinddir: (libc)Random Access Directory.
* rindex: (libc)Search Functions.
* rint: (libc)Rounding Functions.
* rintf: (libc)Rounding Functions.
* rintl: (libc)Rounding Functions.
* rmdir: (libc)Deleting Files.
* round: (libc)Rounding Functions.
* roundf: (libc)Rounding Functions.
* roundl: (libc)Rounding Functions.
* rpmatch: (libc)Yes-or-No Questions.
* sbrk: (libc)Resizing the Data Segment.
* scalb: (libc)Normalization Functions.
* scalbf: (libc)Normalization Functions.
* scalbl: (libc)Normalization Functions.
* scalbln: (libc)Normalization Functions.
* scalblnf: (libc)Normalization Functions.
* scalblnl: (libc)Normalization Functions.
* scalbn: (libc)Normalization Functions.
* scalbnf: (libc)Normalization Functions.
* scalbnl: (libc)Normalization Functions.
* scandir64: (libc)Scanning Directory Content.
* scandir: (libc)Scanning Directory Content.
* scanf: (libc)Formatted Input Functions.
* sched_get_priority_max: (libc)Basic Scheduling Functions.
* sched_get_priority_min: (libc)Basic Scheduling Functions.
* sched_getaffinity: (libc)CPU Affinity.
* sched_getparam: (libc)Basic Scheduling Functions.
* sched_getscheduler: (libc)Basic Scheduling Functions.
* sched_rr_get_interval: (libc)Basic Scheduling Functions.
* sched_setaffinity: (libc)CPU Affinity.
* sched_setparam: (libc)Basic Scheduling Functions.
* sched_setscheduler: (libc)Basic Scheduling Functions.
* sched_yield: (libc)Basic Scheduling Functions.
* secure_getenv: (libc)Environment Access.
* seed48: (libc)SVID Random.
* seed48_r: (libc)SVID Random.
* seekdir: (libc)Random Access Directory.
* select: (libc)Waiting for I/O.
* send: (libc)Sending Data.
* sendmsg: (libc)Receiving Datagrams.
* sendto: (libc)Sending Datagrams.
* setbuf: (libc)Controlling Buffering.
* setbuffer: (libc)Controlling Buffering.
* setcontext: (libc)System V contexts.
* setdomainname: (libc)Host Identification.
* setegid: (libc)Setting Groups.
* setenv: (libc)Environment Access.
* seteuid: (libc)Setting User ID.
* setfsent: (libc)fstab.
* setgid: (libc)Setting Groups.
* setgrent: (libc)Scanning All Groups.
* setgroups: (libc)Setting Groups.
* sethostent: (libc)Host Names.
* sethostid: (libc)Host Identification.
* sethostname: (libc)Host Identification.
* setitimer: (libc)Setting an Alarm.
* setjmp: (libc)Non-Local Details.
* setkey: (libc)DES Encryption.
* setkey_r: (libc)DES Encryption.
* setlinebuf: (libc)Controlling Buffering.
* setlocale: (libc)Setting the Locale.
* setlogmask: (libc)setlogmask.
* setmntent: (libc)mtab.
* setnetent: (libc)Networks Database.
* setnetgrent: (libc)Lookup Netgroup.
* setpgid: (libc)Process Group Functions.
* setpgrp: (libc)Process Group Functions.
* setpriority: (libc)Traditional Scheduling Functions.
* setprotoent: (libc)Protocols Database.
* setpwent: (libc)Scanning All Users.
* setregid: (libc)Setting Groups.
* setreuid: (libc)Setting User ID.
* setrlimit64: (libc)Limits on Resources.
* setrlimit: (libc)Limits on Resources.
* setservent: (libc)Services Database.
* setsid: (libc)Process Group Functions.
* setsockopt: (libc)Socket Option Functions.
* setstate: (libc)BSD Random.
* setstate_r: (libc)BSD Random.
* settimeofday: (libc)High-Resolution Calendar.
* setuid: (libc)Setting User ID.
* setutent: (libc)Manipulating the Database.
* setutxent: (libc)XPG Functions.
* setvbuf: (libc)Controlling Buffering.
* shm_open: (libc)Memory-mapped I/O.
* shm_unlink: (libc)Memory-mapped I/O.
* shutdown: (libc)Closing a Socket.
* sigaction: (libc)Advanced Signal Handling.
* sigaddset: (libc)Signal Sets.
* sigaltstack: (libc)Signal Stack.
* sigblock: (libc)Blocking in BSD.
* sigdelset: (libc)Signal Sets.
* sigemptyset: (libc)Signal Sets.
* sigfillset: (libc)Signal Sets.
* siginterrupt: (libc)BSD Handler.
* sigismember: (libc)Signal Sets.
* siglongjmp: (libc)Non-Local Exits and Signals.
* sigmask: (libc)Blocking in BSD.
* signal: (libc)Basic Signal Handling.
* signbit: (libc)FP Bit Twiddling.
* significand: (libc)Normalization Functions.
* significandf: (libc)Normalization Functions.
* significandl: (libc)Normalization Functions.
* sigpause: (libc)Blocking in BSD.
* sigpending: (libc)Checking for Pending Signals.
* sigprocmask: (libc)Process Signal Mask.
* sigsetjmp: (libc)Non-Local Exits and Signals.
* sigsetmask: (libc)Blocking in BSD.
* sigstack: (libc)Signal Stack.
* sigsuspend: (libc)Sigsuspend.
* sigvec: (libc)BSD Handler.
* sin: (libc)Trig Functions.
* sincos: (libc)Trig Functions.
* sincosf: (libc)Trig Functions.
* sincosl: (libc)Trig Functions.
* sinf: (libc)Trig Functions.
* sinh: (libc)Hyperbolic Functions.
* sinhf: (libc)Hyperbolic Functions.
* sinhl: (libc)Hyperbolic Functions.
* sinl: (libc)Trig Functions.
* sleep: (libc)Sleeping.
* snprintf: (libc)Formatted Output Functions.
* socket: (libc)Creating a Socket.
* socketpair: (libc)Socket Pairs.
* sprintf: (libc)Formatted Output Functions.
* sqrt: (libc)Exponents and Logarithms.
* sqrtf: (libc)Exponents and Logarithms.
* sqrtl: (libc)Exponents and Logarithms.
* srand48: (libc)SVID Random.
* srand48_r: (libc)SVID Random.
* srand: (libc)ISO Random.
* srandom: (libc)BSD Random.
* srandom_r: (libc)BSD Random.
* sscanf: (libc)Formatted Input Functions.
* ssignal: (libc)Basic Signal Handling.
* stat64: (libc)Reading Attributes.
* stat: (libc)Reading Attributes.
* stime: (libc)Simple Calendar Time.
* stpcpy: (libc)Copying and Concatenation.
* stpncpy: (libc)Copying and Concatenation.
* strcasecmp: (libc)String/Array Comparison.
* strcasestr: (libc)Search Functions.
* strcat: (libc)Copying and Concatenation.
* strchr: (libc)Search Functions.
* strchrnul: (libc)Search Functions.
* strcmp: (libc)String/Array Comparison.
* strcoll: (libc)Collation Functions.
* strcpy: (libc)Copying and Concatenation.
* strcspn: (libc)Search Functions.
* strdup: (libc)Copying and Concatenation.
* strdupa: (libc)Copying and Concatenation.
* strerror: (libc)Error Messages.
* strerror_r: (libc)Error Messages.
* strfmon: (libc)Formatting Numbers.
* strfry: (libc)strfry.
* strftime: (libc)Formatting Calendar Time.
* strlen: (libc)String Length.
* strncasecmp: (libc)String/Array Comparison.
* strncat: (libc)Copying and Concatenation.
* strncmp: (libc)String/Array Comparison.
* strncpy: (libc)Copying and Concatenation.
* strndup: (libc)Copying and Concatenation.
* strndupa: (libc)Copying and Concatenation.
* strnlen: (libc)String Length.
* strpbrk: (libc)Search Functions.
* strptime: (libc)Low-Level Time String Parsing.
* strrchr: (libc)Search Functions.
* strsep: (libc)Finding Tokens in a String.
* strsignal: (libc)Signal Messages.
* strspn: (libc)Search Functions.
* strstr: (libc)Search Functions.
* strtod: (libc)Parsing of Floats.
* strtof: (libc)Parsing of Floats.
* strtoimax: (libc)Parsing of Integers.
* strtok: (libc)Finding Tokens in a String.
* strtok_r: (libc)Finding Tokens in a String.
* strtol: (libc)Parsing of Integers.
* strtold: (libc)Parsing of Floats.
* strtoll: (libc)Parsing of Integers.
* strtoq: (libc)Parsing of Integers.
* strtoul: (libc)Parsing of Integers.
* strtoull: (libc)Parsing of Integers.
* strtoumax: (libc)Parsing of Integers.
* strtouq: (libc)Parsing of Integers.
* strverscmp: (libc)String/Array Comparison.
* strxfrm: (libc)Collation Functions.
* stty: (libc)BSD Terminal Modes.
* swapcontext: (libc)System V contexts.
* swprintf: (libc)Formatted Output Functions.
* swscanf: (libc)Formatted Input Functions.
* symlink: (libc)Symbolic Links.
* sync: (libc)Synchronizing I/O.
* syscall: (libc)System Calls.
* sysconf: (libc)Sysconf Definition.
* sysctl: (libc)System Parameters.
* syslog: (libc)syslog; vsyslog.
* system: (libc)Running a Command.
* sysv_signal: (libc)Basic Signal Handling.
* tan: (libc)Trig Functions.
* tanf: (libc)Trig Functions.
* tanh: (libc)Hyperbolic Functions.
* tanhf: (libc)Hyperbolic Functions.
* tanhl: (libc)Hyperbolic Functions.
* tanl: (libc)Trig Functions.
* tcdrain: (libc)Line Control.
* tcflow: (libc)Line Control.
* tcflush: (libc)Line Control.
* tcgetattr: (libc)Mode Functions.
* tcgetpgrp: (libc)Terminal Access Functions.
* tcgetsid: (libc)Terminal Access Functions.
* tcsendbreak: (libc)Line Control.
* tcsetattr: (libc)Mode Functions.
* tcsetpgrp: (libc)Terminal Access Functions.
* tdelete: (libc)Tree Search Function.
* tdestroy: (libc)Tree Search Function.
* telldir: (libc)Random Access Directory.
* tempnam: (libc)Temporary Files.
* textdomain: (libc)Locating gettext catalog.
* tfind: (libc)Tree Search Function.
* tgamma: (libc)Special Functions.
* tgammaf: (libc)Special Functions.
* tgammal: (libc)Special Functions.
* time: (libc)Simple Calendar Time.
* timegm: (libc)Broken-down Time.
* timelocal: (libc)Broken-down Time.
* times: (libc)Processor Time.
* tmpfile64: (libc)Temporary Files.
* tmpfile: (libc)Temporary Files.
* tmpnam: (libc)Temporary Files.
* tmpnam_r: (libc)Temporary Files.
* toascii: (libc)Case Conversion.
* tolower: (libc)Case Conversion.
* toupper: (libc)Case Conversion.
* towctrans: (libc)Wide Character Case Conversion.
* towlower: (libc)Wide Character Case Conversion.
* towupper: (libc)Wide Character Case Conversion.
* trunc: (libc)Rounding Functions.
* truncate64: (libc)File Size.
* truncate: (libc)File Size.
* truncf: (libc)Rounding Functions.
* truncl: (libc)Rounding Functions.
* tsearch: (libc)Tree Search Function.
* ttyname: (libc)Is It a Terminal.
* ttyname_r: (libc)Is It a Terminal.
* twalk: (libc)Tree Search Function.
* tzset: (libc)Time Zone Functions.
* ulimit: (libc)Limits on Resources.
* umask: (libc)Setting Permissions.
* umount2: (libc)Mount-Unmount-Remount.
* umount: (libc)Mount-Unmount-Remount.
* uname: (libc)Platform Type.
* ungetc: (libc)How Unread.
* ungetwc: (libc)How Unread.
* unlink: (libc)Deleting Files.
* unlockpt: (libc)Allocation.
* unsetenv: (libc)Environment Access.
* updwtmp: (libc)Manipulating the Database.
* utime: (libc)File Times.
* utimes: (libc)File Times.
* utmpname: (libc)Manipulating the Database.
* utmpxname: (libc)XPG Functions.
* va_arg: (libc)Argument Macros.
* va_copy: (libc)Argument Macros.
* va_end: (libc)Argument Macros.
* va_start: (libc)Argument Macros.
* valloc: (libc)Aligned Memory Blocks.
* vasprintf: (libc)Variable Arguments Output.
* verr: (libc)Error Messages.
* verrx: (libc)Error Messages.
* versionsort64: (libc)Scanning Directory Content.
* versionsort: (libc)Scanning Directory Content.
* vfork: (libc)Creating a Process.
* vfprintf: (libc)Variable Arguments Output.
* vfscanf: (libc)Variable Arguments Input.
* vfwprintf: (libc)Variable Arguments Output.
* vfwscanf: (libc)Variable Arguments Input.
* vlimit: (libc)Limits on Resources.
* vprintf: (libc)Variable Arguments Output.
* vscanf: (libc)Variable Arguments Input.
* vsnprintf: (libc)Variable Arguments Output.
* vsprintf: (libc)Variable Arguments Output.
* vsscanf: (libc)Variable Arguments Input.
* vswprintf: (libc)Variable Arguments Output.
* vswscanf: (libc)Variable Arguments Input.
* vsyslog: (libc)syslog; vsyslog.
* vtimes: (libc)Resource Usage.
* vwarn: (libc)Error Messages.
* vwarnx: (libc)Error Messages.
* vwprintf: (libc)Variable Arguments Output.
* vwscanf: (libc)Variable Arguments Input.
* wait3: (libc)BSD Wait Functions.
* wait4: (libc)Process Completion.
* wait: (libc)Process Completion.
* waitpid: (libc)Process Completion.
* warn: (libc)Error Messages.
* warnx: (libc)Error Messages.
* wcpcpy: (libc)Copying and Concatenation.
* wcpncpy: (libc)Copying and Concatenation.
* wcrtomb: (libc)Converting a Character.
* wcscasecmp: (libc)String/Array Comparison.
* wcscat: (libc)Copying and Concatenation.
* wcschr: (libc)Search Functions.
* wcschrnul: (libc)Search Functions.
* wcscmp: (libc)String/Array Comparison.
* wcscoll: (libc)Collation Functions.
* wcscpy: (libc)Copying and Concatenation.
* wcscspn: (libc)Search Functions.
* wcsdup: (libc)Copying and Concatenation.
* wcsftime: (libc)Formatting Calendar Time.
* wcslen: (libc)String Length.
* wcsncasecmp: (libc)String/Array Comparison.
* wcsncat: (libc)Copying and Concatenation.
* wcsncmp: (libc)String/Array Comparison.
* wcsncpy: (libc)Copying and Concatenation.
* wcsnlen: (libc)String Length.
* wcsnrtombs: (libc)Converting Strings.
* wcspbrk: (libc)Search Functions.
* wcsrchr: (libc)Search Functions.
* wcsrtombs: (libc)Converting Strings.
* wcsspn: (libc)Search Functions.
* wcsstr: (libc)Search Functions.
* wcstod: (libc)Parsing of Floats.
* wcstof: (libc)Parsing of Floats.
* wcstoimax: (libc)Parsing of Integers.
* wcstok: (libc)Finding Tokens in a String.
* wcstol: (libc)Parsing of Integers.
* wcstold: (libc)Parsing of Floats.
* wcstoll: (libc)Parsing of Integers.
* wcstombs: (libc)Non-reentrant String Conversion.
* wcstoq: (libc)Parsing of Integers.
* wcstoul: (libc)Parsing of Integers.
* wcstoull: (libc)Parsing of Integers.
* wcstoumax: (libc)Parsing of Integers.
* wcstouq: (libc)Parsing of Integers.
* wcswcs: (libc)Search Functions.
* wcsxfrm: (libc)Collation Functions.
* wctob: (libc)Converting a Character.
* wctomb: (libc)Non-reentrant Character Conversion.
* wctrans: (libc)Wide Character Case Conversion.
* wctype: (libc)Classification of Wide Characters.
* wmemchr: (libc)Search Functions.
* wmemcmp: (libc)String/Array Comparison.
* wmemcpy: (libc)Copying and Concatenation.
* wmemmove: (libc)Copying and Concatenation.
* wmempcpy: (libc)Copying and Concatenation.
* wmemset: (libc)Copying and Concatenation.
* wordexp: (libc)Calling Wordexp.
* wordfree: (libc)Calling Wordexp.
* wprintf: (libc)Formatted Output Functions.
* write: (libc)I/O Primitives.
* writev: (libc)Scatter-Gather.
* wscanf: (libc)Formatted Input Functions.
* y0: (libc)Special Functions.
* y0f: (libc)Special Functions.
* y0l: (libc)Special Functions.
* y1: (libc)Special Functions.
* y1f: (libc)Special Functions.
* y1l: (libc)Special Functions.
* yn: (libc)Special Functions.
* ynf: (libc)Special Functions.
* ynl: (libc)Special Functions.
END-INFO-DIR-ENTRY


File: libc.info,  Node: Canonical or Not,  Next: Terminal Modes,  Prev: I/O Queues,  Up: Low-Level Terminal Interface

17.3 Two Styles of Input: Canonical or Not
==========================================

POSIX systems support two basic modes of input: canonical and
noncanonical.

   In "canonical input processing" mode, terminal input is processed in
lines terminated by newline (''\n''), EOF, or EOL characters.  No input
can be read until an entire line has been typed by the user, and the
'read' function (*note I/O Primitives::) returns at most a single line
of input, no matter how many bytes are requested.

   In canonical input mode, the operating system provides input editing
facilities: some characters are interpreted specially to perform editing
operations within the current line of text, such as ERASE and KILL.
*Note Editing Characters::.

   The constants '_POSIX_MAX_CANON' and 'MAX_CANON' parameterize the
maximum number of bytes which may appear in a single line of canonical
input.  *Note Limits for Files::.  You are guaranteed a maximum line
length of at least 'MAX_CANON' bytes, but the maximum might be larger,
and might even dynamically change size.

   In "noncanonical input processing" mode, characters are not grouped
into lines, and ERASE and KILL processing is not performed.  The
granularity with which bytes are read in noncanonical input mode is
controlled by the MIN and TIME settings.  *Note Noncanonical Input::.

   Most programs use canonical input mode, because this gives the user a
way to edit input line by line.  The usual reason to use noncanonical
mode is when the program accepts single-character commands or provides
its own editing facilities.

   The choice of canonical or noncanonical input is controlled by the
'ICANON' flag in the 'c_lflag' member of 'struct termios'.  *Note Local
Modes::.


File: libc.info,  Node: Terminal Modes,  Next: BSD Terminal Modes,  Prev: Canonical or Not,  Up: Low-Level Terminal Interface

17.4 Terminal Modes
===================

This section describes the various terminal attributes that control how
input and output are done.  The functions, data structures, and symbolic
constants are all declared in the header file 'termios.h'.

   Don't confuse terminal attributes with file attributes.  A device
special file which is associated with a terminal has file attributes as
described in *note File Attributes::.  These are unrelated to the
attributes of the terminal device itself, which are discussed in this
section.

* Menu:

* Mode Data Types::             The data type 'struct termios' and
                                 related types.
* Mode Functions::              Functions to read and set the terminal
                                 attributes.
* Setting Modes::               The right way to set terminal attributes
                                 reliably.
* Input Modes::                 Flags controlling low-level input handling.
* Output Modes::                Flags controlling low-level output handling.
* Control Modes::               Flags controlling serial port behavior.
* Local Modes::                 Flags controlling high-level input handling.
* Line Speed::                  How to read and set the terminal line speed.
* Special Characters::          Characters that have special effects,
			         and how to change them.
* Noncanonical Input::          Controlling how long to wait for input.


File: libc.info,  Node: Mode Data Types,  Next: Mode Functions,  Up: Terminal Modes

17.4.1 Terminal Mode Data Types
-------------------------------

The entire collection of attributes of a terminal is stored in a
structure of type 'struct termios'.  This structure is used with the
functions 'tcgetattr' and 'tcsetattr' to read and set the attributes.

 -- Data Type: struct termios
     Structure that records all the I/O attributes of a terminal.  The
     structure includes at least the following members:

     'tcflag_t c_iflag'
          A bit mask specifying flags for input modes; see *note Input
          Modes::.

     'tcflag_t c_oflag'
          A bit mask specifying flags for output modes; see *note Output
          Modes::.

     'tcflag_t c_cflag'
          A bit mask specifying flags for control modes; see *note
          Control Modes::.

     'tcflag_t c_lflag'
          A bit mask specifying flags for local modes; see *note Local
          Modes::.

     'cc_t c_cc[NCCS]'
          An array specifying which characters are associated with
          various control functions; see *note Special Characters::.

     The 'struct termios' structure also contains members which encode
     input and output transmission speeds, but the representation is not
     specified.  *Note Line Speed::, for how to examine and store the
     speed values.

   The following sections describe the details of the members of the
'struct termios' structure.

 -- Data Type: tcflag_t
     This is an unsigned integer type used to represent the various bit
     masks for terminal flags.

 -- Data Type: cc_t
     This is an unsigned integer type used to represent characters
     associated with various terminal control functions.

 -- Macro: int NCCS
     The value of this macro is the number of elements in the 'c_cc'
     array.


File: libc.info,  Node: Mode Functions,  Next: Setting Modes,  Prev: Mode Data Types,  Up: Terminal Modes

17.4.2 Terminal Mode Functions
------------------------------

 -- Function: int tcgetattr (int FILEDES, struct termios *TERMIOS-P)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     This function is used to examine the attributes of the terminal
     device with file descriptor FILEDES.  The attributes are returned
     in the structure that TERMIOS-P points to.

     If successful, 'tcgetattr' returns 0.  A return value of -1
     indicates an error.  The following 'errno' error conditions are
     defined for this function:

     'EBADF'
          The FILEDES argument is not a valid file descriptor.

     'ENOTTY'
          The FILEDES is not associated with a terminal.

 -- Function: int tcsetattr (int FILEDES, int WHEN, const struct termios
          *TERMIOS-P)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     This function sets the attributes of the terminal device with file
     descriptor FILEDES.  The new attributes are taken from the
     structure that TERMIOS-P points to.

     The WHEN argument specifies how to deal with input and output
     already queued.  It can be one of the following values:

     'TCSANOW'
          Make the change immediately.

     'TCSADRAIN'
          Make the change after waiting until all queued output has been
          written.  You should usually use this option when changing
          parameters that affect output.

     'TCSAFLUSH'
          This is like 'TCSADRAIN', but also discards any queued input.

     'TCSASOFT'
          This is a flag bit that you can add to any of the above
          alternatives.  Its meaning is to inhibit alteration of the
          state of the terminal hardware.  It is a BSD extension; it is
          only supported on BSD systems and GNU/Hurd systems.

          Using 'TCSASOFT' is exactly the same as setting the 'CIGNORE'
          bit in the 'c_cflag' member of the structure TERMIOS-P points
          to.  *Note Control Modes::, for a description of 'CIGNORE'.

     If this function is called from a background process on its
     controlling terminal, normally all processes in the process group
     are sent a 'SIGTTOU' signal, in the same way as if the process were
     trying to write to the terminal.  The exception is if the calling
     process itself is ignoring or blocking 'SIGTTOU' signals, in which
     case the operation is performed and no signal is sent.  *Note Job
     Control::.

     If successful, 'tcsetattr' returns 0.  A return value of -1
     indicates an error.  The following 'errno' error conditions are
     defined for this function:

     'EBADF'
          The FILEDES argument is not a valid file descriptor.

     'ENOTTY'
          The FILEDES is not associated with a terminal.

     'EINVAL'
          Either the value of the 'when' argument is not valid, or there
          is something wrong with the data in the TERMIOS-P argument.

   Although 'tcgetattr' and 'tcsetattr' specify the terminal device with
a file descriptor, the attributes are those of the terminal device
itself and not of the file descriptor.  This means that the effects of
changing terminal attributes are persistent; if another process opens
the terminal file later on, it will see the changed attributes even
though it doesn't have anything to do with the open file descriptor you
originally specified in changing the attributes.

   Similarly, if a single process has multiple or duplicated file
descriptors for the same terminal device, changing the terminal
attributes affects input and output to all of these file descriptors.
This means, for example, that you can't open one file descriptor or
stream to read from a terminal in the normal line-buffered, echoed mode;
and simultaneously have another file descriptor for the same terminal
that you use to read from it in single-character, non-echoed mode.
Instead, you have to explicitly switch the terminal back and forth
between the two modes.


File: libc.info,  Node: Setting Modes,  Next: Input Modes,  Prev: Mode Functions,  Up: Terminal Modes

17.4.3 Setting Terminal Modes Properly
--------------------------------------

When you set terminal modes, you should call 'tcgetattr' first to get
the current modes of the particular terminal device, modify only those
modes that you are really interested in, and store the result with
'tcsetattr'.

   It's a bad idea to simply initialize a 'struct termios' structure to
a chosen set of attributes and pass it directly to 'tcsetattr'.  Your
program may be run years from now, on systems that support members not
documented in this manual.  The way to avoid setting these members to
unreasonable values is to avoid changing them.

   What's more, different terminal devices may require different mode
settings in order to function properly.  So you should avoid blindly
copying attributes from one terminal device to another.

   When a member contains a collection of independent flags, as the
'c_iflag', 'c_oflag' and 'c_cflag' members do, even setting the entire
member is a bad idea, because particular operating systems have their
own flags.  Instead, you should start with the current value of the
member and alter only the flags whose values matter in your program,
leaving any other flags unchanged.

   Here is an example of how to set one flag ('ISTRIP') in the 'struct
termios' structure while properly preserving all the other data in the
structure:

     int
     set_istrip (int desc, int value)
     {
       struct termios settings;
       int result;

       result = tcgetattr (desc, &settings);
       if (result < 0)
         {
           perror ("error in tcgetattr");
           return 0;
         }
       settings.c_iflag &= ~ISTRIP;
       if (value)
         settings.c_iflag |= ISTRIP;
       result = tcsetattr (desc, TCSANOW, &settings);
       if (result < 0)
         {
           perror ("error in tcsetattr");
           return 0;
        }
       return 1;
     }


File: libc.info,  Node: Input Modes,  Next: Output Modes,  Prev: Setting Modes,  Up: Terminal Modes

17.4.4 Input Modes
------------------

This section describes the terminal attribute flags that control fairly
low-level aspects of input processing: handling of parity errors, break
signals, flow control, and <RET> and <LFD> characters.

   All of these flags are bits in the 'c_iflag' member of the 'struct
termios' structure.  The member is an integer, and you change flags
using the operators '&', '|' and '^'.  Don't try to specify the entire
value for 'c_iflag'--instead, change only specific flags and leave the
rest untouched (*note Setting Modes::).

 -- Macro: tcflag_t INPCK
     If this bit is set, input parity checking is enabled.  If it is not
     set, no checking at all is done for parity errors on input; the
     characters are simply passed through to the application.

     Parity checking on input processing is independent of whether
     parity detection and generation on the underlying terminal hardware
     is enabled; see *note Control Modes::.  For example, you could
     clear the 'INPCK' input mode flag and set the 'PARENB' control mode
     flag to ignore parity errors on input, but still generate parity on
     output.

     If this bit is set, what happens when a parity error is detected
     depends on whether the 'IGNPAR' or 'PARMRK' bits are set.  If
     neither of these bits are set, a byte with a parity error is passed
     to the application as a ''\0'' character.

 -- Macro: tcflag_t IGNPAR
     If this bit is set, any byte with a framing or parity error is
     ignored.  This is only useful if 'INPCK' is also set.

 -- Macro: tcflag_t PARMRK
     If this bit is set, input bytes with parity or framing errors are
     marked when passed to the program.  This bit is meaningful only
     when 'INPCK' is set and 'IGNPAR' is not set.

     The way erroneous bytes are marked is with two preceding bytes,
     '377' and '0'.  Thus, the program actually reads three bytes for
     one erroneous byte received from the terminal.

     If a valid byte has the value '0377', and 'ISTRIP' (see below) is
     not set, the program might confuse it with the prefix that marks a
     parity error.  So a valid byte '0377' is passed to the program as
     two bytes, '0377' '0377', in this case.

 -- Macro: tcflag_t ISTRIP
     If this bit is set, valid input bytes are stripped to seven bits;
     otherwise, all eight bits are available for programs to read.

 -- Macro: tcflag_t IGNBRK
     If this bit is set, break conditions are ignored.

     A "break condition" is defined in the context of asynchronous
     serial data transmission as a series of zero-value bits longer than
     a single byte.

 -- Macro: tcflag_t BRKINT
     If this bit is set and 'IGNBRK' is not set, a break condition
     clears the terminal input and output queues and raises a 'SIGINT'
     signal for the foreground process group associated with the
     terminal.

     If neither 'BRKINT' nor 'IGNBRK' are set, a break condition is
     passed to the application as a single ''\0'' character if 'PARMRK'
     is not set, or otherwise as a three-character sequence ''\377'',
     ''\0'', ''\0''.

 -- Macro: tcflag_t IGNCR
     If this bit is set, carriage return characters (''\r'') are
     discarded on input.  Discarding carriage return may be useful on
     terminals that send both carriage return and linefeed when you type
     the <RET> key.

 -- Macro: tcflag_t ICRNL
     If this bit is set and 'IGNCR' is not set, carriage return
     characters (''\r'') received as input are passed to the application
     as newline characters (''\n'').

 -- Macro: tcflag_t INLCR
     If this bit is set, newline characters (''\n'') received as input
     are passed to the application as carriage return characters
     (''\r'').

 -- Macro: tcflag_t IXOFF
     If this bit is set, start/stop control on input is enabled.  In
     other words, the computer sends STOP and START characters as
     necessary to prevent input from coming in faster than programs are
     reading it.  The idea is that the actual terminal hardware that is
     generating the input data responds to a STOP character by
     suspending transmission, and to a START character by resuming
     transmission.  *Note Start/Stop Characters::.

 -- Macro: tcflag_t IXON
     If this bit is set, start/stop control on output is enabled.  In
     other words, if the computer receives a STOP character, it suspends
     output until a START character is received.  In this case, the STOP
     and START characters are never passed to the application program.
     If this bit is not set, then START and STOP can be read as ordinary
     characters.  *Note Start/Stop Characters::.

 -- Macro: tcflag_t IXANY
     If this bit is set, any input character restarts output when output
     has been suspended with the STOP character.  Otherwise, only the
     START character restarts output.

     This is a BSD extension; it exists only on BSD systems and
     GNU/Linux and GNU/Hurd systems.

 -- Macro: tcflag_t IMAXBEL
     If this bit is set, then filling up the terminal input buffer sends
     a BEL character (code '007') to the terminal to ring the bell.

     This is a BSD extension.


File: libc.info,  Node: Output Modes,  Next: Control Modes,  Prev: Input Modes,  Up: Terminal Modes

17.4.5 Output Modes
-------------------

This section describes the terminal flags and fields that control how
output characters are translated and padded for display.  All of these
are contained in the 'c_oflag' member of the 'struct termios' structure.

   The 'c_oflag' member itself is an integer, and you change the flags
and fields using the operators '&', '|', and '^'.  Don't try to specify
the entire value for 'c_oflag'--instead, change only specific flags and
leave the rest untouched (*note Setting Modes::).

 -- Macro: tcflag_t OPOST
     If this bit is set, output data is processed in some unspecified
     way so that it is displayed appropriately on the terminal device.
     This typically includes mapping newline characters (''\n'') onto
     carriage return and linefeed pairs.

     If this bit isn't set, the characters are transmitted as-is.

   The following three bits are effective only if 'OPOST' is set.

 -- Macro: tcflag_t ONLCR
     If this bit is set, convert the newline character on output into a
     pair of characters, carriage return followed by linefeed.

 -- Macro: tcflag_t OXTABS
     If this bit is set, convert tab characters on output into the
     appropriate number of spaces to emulate a tab stop every eight
     columns.  This bit exists only on BSD systems and GNU/Hurd systems;
     on GNU/Linux systems it is available as 'XTABS'.

 -- Macro: tcflag_t ONOEOT
     If this bit is set, discard 'C-d' characters (code '004') on
     output.  These characters cause many dial-up terminals to
     disconnect.  This bit exists only on BSD systems and GNU/Hurd
     systems.


File: libc.info,  Node: Control Modes,  Next: Local Modes,  Prev: Output Modes,  Up: Terminal Modes

17.4.6 Control Modes
--------------------

This section describes the terminal flags and fields that control
parameters usually associated with asynchronous serial data
transmission.  These flags may not make sense for other kinds of
terminal ports (such as a network connection pseudo-terminal).  All of
these are contained in the 'c_cflag' member of the 'struct termios'
structure.

   The 'c_cflag' member itself is an integer, and you change the flags
and fields using the operators '&', '|', and '^'.  Don't try to specify
the entire value for 'c_cflag'--instead, change only specific flags and
leave the rest untouched (*note Setting Modes::).

 -- Macro: tcflag_t CLOCAL
     If this bit is set, it indicates that the terminal is connected
     "locally" and that the modem status lines (such as carrier detect)
     should be ignored.

     On many systems if this bit is not set and you call 'open' without
     the 'O_NONBLOCK' flag set, 'open' blocks until a modem connection
     is established.

     If this bit is not set and a modem disconnect is detected, a
     'SIGHUP' signal is sent to the controlling process group for the
     terminal (if it has one).  Normally, this causes the process to
     exit; see *note Signal Handling::.  Reading from the terminal after
     a disconnect causes an end-of-file condition, and writing causes an
     'EIO' error to be returned.  The terminal device must be closed and
     reopened to clear the condition.

 -- Macro: tcflag_t HUPCL
     If this bit is set, a modem disconnect is generated when all
     processes that have the terminal device open have either closed the
     file or exited.

 -- Macro: tcflag_t CREAD
     If this bit is set, input can be read from the terminal.
     Otherwise, input is discarded when it arrives.

 -- Macro: tcflag_t CSTOPB
     If this bit is set, two stop bits are used.  Otherwise, only one
     stop bit is used.

 -- Macro: tcflag_t PARENB
     If this bit is set, generation and detection of a parity bit are
     enabled.  *Note Input Modes::, for information on how input parity
     errors are handled.

     If this bit is not set, no parity bit is added to output
     characters, and input characters are not checked for correct
     parity.

 -- Macro: tcflag_t PARODD
     This bit is only useful if 'PARENB' is set.  If 'PARODD' is set,
     odd parity is used, otherwise even parity is used.

   The control mode flags also includes a field for the number of bits
per character.  You can use the 'CSIZE' macro as a mask to extract the
value, like this: 'settings.c_cflag & CSIZE'.

 -- Macro: tcflag_t CSIZE
     This is a mask for the number of bits per character.

 -- Macro: tcflag_t CS5
     This specifies five bits per byte.

 -- Macro: tcflag_t CS6
     This specifies six bits per byte.

 -- Macro: tcflag_t CS7
     This specifies seven bits per byte.

 -- Macro: tcflag_t CS8
     This specifies eight bits per byte.

   The following four bits are BSD extensions; these exist only on BSD
systems and GNU/Hurd systems.

 -- Macro: tcflag_t CCTS_OFLOW
     If this bit is set, enable flow control of output based on the CTS
     wire (RS232 protocol).

 -- Macro: tcflag_t CRTS_IFLOW
     If this bit is set, enable flow control of input based on the RTS
     wire (RS232 protocol).

 -- Macro: tcflag_t MDMBUF
     If this bit is set, enable carrier-based flow control of output.

 -- Macro: tcflag_t CIGNORE
     If this bit is set, it says to ignore the control modes and line
     speed values entirely.  This is only meaningful in a call to
     'tcsetattr'.

     The 'c_cflag' member and the line speed values returned by
     'cfgetispeed' and 'cfgetospeed' will be unaffected by the call.
     'CIGNORE' is useful if you want to set all the software modes in
     the other members, but leave the hardware details in 'c_cflag'
     unchanged.  (This is how the 'TCSASOFT' flag to 'tcsettattr'
     works.)

     This bit is never set in the structure filled in by 'tcgetattr'.


File: libc.info,  Node: Local Modes,  Next: Line Speed,  Prev: Control Modes,  Up: Terminal Modes

17.4.7 Local Modes
------------------

This section describes the flags for the 'c_lflag' member of the 'struct
termios' structure.  These flags generally control higher-level aspects
of input processing than the input modes flags described in *note Input
Modes::, such as echoing, signals, and the choice of canonical or
noncanonical input.

   The 'c_lflag' member itself is an integer, and you change the flags
and fields using the operators '&', '|', and '^'.  Don't try to specify
the entire value for 'c_lflag'--instead, change only specific flags and
leave the rest untouched (*note Setting Modes::).

 -- Macro: tcflag_t ICANON
     This bit, if set, enables canonical input processing mode.
     Otherwise, input is processed in noncanonical mode.  *Note
     Canonical or Not::.

 -- Macro: tcflag_t ECHO
     If this bit is set, echoing of input characters back to the
     terminal is enabled.

 -- Macro: tcflag_t ECHOE
     If this bit is set, echoing indicates erasure of input with the
     ERASE character by erasing the last character in the current line
     from the screen.  Otherwise, the character erased is re-echoed to
     show what has happened (suitable for a printing terminal).

     This bit only controls the display behavior; the 'ICANON' bit by
     itself controls actual recognition of the ERASE character and
     erasure of input, without which 'ECHOE' is simply irrelevant.

 -- Macro: tcflag_t ECHOPRT
     This bit is like 'ECHOE', enables display of the ERASE character in
     a way that is geared to a hardcopy terminal.  When you type the
     ERASE character, a '\' character is printed followed by the first
     character erased.  Typing the ERASE character again just prints the
     next character erased.  Then, the next time you type a normal
     character, a '/' character is printed before the character echoes.

     This is a BSD extension, and exists only in BSD systems and
     GNU/Linux and GNU/Hurd systems.

 -- Macro: tcflag_t ECHOK
     This bit enables special display of the KILL character by moving to
     a new line after echoing the KILL character normally.  The behavior
     of 'ECHOKE' (below) is nicer to look at.

     If this bit is not set, the KILL character echoes just as it would
     if it were not the KILL character.  Then it is up to the user to
     remember that the KILL character has erased the preceding input;
     there is no indication of this on the screen.

     This bit only controls the display behavior; the 'ICANON' bit by
     itself controls actual recognition of the KILL character and
     erasure of input, without which 'ECHOK' is simply irrelevant.

 -- Macro: tcflag_t ECHOKE
     This bit is similar to 'ECHOK'.  It enables special display of the
     KILL character by erasing on the screen the entire line that has
     been killed.  This is a BSD extension, and exists only in BSD
     systems and GNU/Linux and GNU/Hurd systems.

 -- Macro: tcflag_t ECHONL
     If this bit is set and the 'ICANON' bit is also set, then the
     newline (''\n'') character is echoed even if the 'ECHO' bit is not
     set.

 -- Macro: tcflag_t ECHOCTL
     If this bit is set and the 'ECHO' bit is also set, echo control
     characters with '^' followed by the corresponding text character.
     Thus, control-A echoes as '^A'.  This is usually the preferred mode
     for interactive input, because echoing a control character back to
     the terminal could have some undesired effect on the terminal.

     This is a BSD extension, and exists only in BSD systems and
     GNU/Linux and GNU/Hurd systems.

 -- Macro: tcflag_t ISIG
     This bit controls whether the INTR, QUIT, and SUSP characters are
     recognized.  The functions associated with these characters are
     performed if and only if this bit is set.  Being in canonical or
     noncanonical input mode has no affect on the interpretation of
     these characters.

     You should use caution when disabling recognition of these
     characters.  Programs that cannot be interrupted interactively are
     very user-unfriendly.  If you clear this bit, your program should
     provide some alternate interface that allows the user to
     interactively send the signals associated with these characters, or
     to escape from the program.

     *Note Signal Characters::.

 -- Macro: tcflag_t IEXTEN
     POSIX.1 gives 'IEXTEN' implementation-defined meaning, so you
     cannot rely on this interpretation on all systems.

     On BSD systems and GNU/Linux and GNU/Hurd systems, it enables the
     LNEXT and DISCARD characters.  *Note Other Special::.

 -- Macro: tcflag_t NOFLSH
     Normally, the INTR, QUIT, and SUSP characters cause input and
     output queues for the terminal to be cleared.  If this bit is set,
     the queues are not cleared.

 -- Macro: tcflag_t TOSTOP
     If this bit is set and the system supports job control, then
     'SIGTTOU' signals are generated by background processes that
     attempt to write to the terminal.  *Note Access to the Terminal::.

   The following bits are BSD extensions; they exist only on BSD systems
and GNU/Hurd systems.

 -- Macro: tcflag_t ALTWERASE
     This bit determines how far the WERASE character should erase.  The
     WERASE character erases back to the beginning of a word; the
     question is, where do words begin?

     If this bit is clear, then the beginning of a word is a
     nonwhitespace character following a whitespace character.  If the
     bit is set, then the beginning of a word is an alphanumeric
     character or underscore following a character which is none of
     those.

     *Note Editing Characters::, for more information about the WERASE
     character.

 -- Macro: tcflag_t FLUSHO
     This is the bit that toggles when the user types the DISCARD
     character.  While this bit is set, all output is discarded.  *Note
     Other Special::.

 -- Macro: tcflag_t NOKERNINFO
     Setting this bit disables handling of the STATUS character.  *Note
     Other Special::.

 -- Macro: tcflag_t PENDIN
     If this bit is set, it indicates that there is a line of input that
     needs to be reprinted.  Typing the REPRINT character sets this bit;
     the bit remains set until reprinting is finished.  *Note Editing
     Characters::.


File: libc.info,  Node: Line Speed,  Next: Special Characters,  Prev: Local Modes,  Up: Terminal Modes

17.4.8 Line Speed
-----------------

The terminal line speed tells the computer how fast to read and write
data on the terminal.

   If the terminal is connected to a real serial line, the terminal
speed you specify actually controls the line--if it doesn't match the
terminal's own idea of the speed, communication does not work.  Real
serial ports accept only certain standard speeds.  Also, particular
hardware may not support even all the standard speeds.  Specifying a
speed of zero hangs up a dialup connection and turns off modem control
signals.

   If the terminal is not a real serial line (for example, if it is a
network connection), then the line speed won't really affect data
transmission speed, but some programs will use it to determine the
amount of padding needed.  It's best to specify a line speed value that
matches the actual speed of the actual terminal, but you can safely
experiment with different values to vary the amount of padding.

   There are actually two line speeds for each terminal, one for input
and one for output.  You can set them independently, but most often
terminals use the same speed for both directions.

   The speed values are stored in the 'struct termios' structure, but
don't try to access them in the 'struct termios' structure directly.
Instead, you should use the following functions to read and store them:

 -- Function: speed_t cfgetospeed (const struct termios *TERMIOS-P)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     This function returns the output line speed stored in the structure
     '*TERMIOS-P'.

 -- Function: speed_t cfgetispeed (const struct termios *TERMIOS-P)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     This function returns the input line speed stored in the structure
     '*TERMIOS-P'.

 -- Function: int cfsetospeed (struct termios *TERMIOS-P, speed_t SPEED)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     This function stores SPEED in '*TERMIOS-P' as the output speed.
     The normal return value is 0; a value of -1 indicates an error.  If
     SPEED is not a speed, 'cfsetospeed' returns -1.

 -- Function: int cfsetispeed (struct termios *TERMIOS-P, speed_t SPEED)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     This function stores SPEED in '*TERMIOS-P' as the input speed.  The
     normal return value is 0; a value of -1 indicates an error.  If
     SPEED is not a speed, 'cfsetospeed' returns -1.

 -- Function: int cfsetspeed (struct termios *TERMIOS-P, speed_t SPEED)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     This function stores SPEED in '*TERMIOS-P' as both the input and
     output speeds.  The normal return value is 0; a value of -1
     indicates an error.  If SPEED is not a speed, 'cfsetspeed' returns
     -1.  This function is an extension in 4.4 BSD.

 -- Data Type: speed_t
     The 'speed_t' type is an unsigned integer data type used to
     represent line speeds.

   The functions 'cfsetospeed' and 'cfsetispeed' report errors only for
speed values that the system simply cannot handle.  If you specify a
speed value that is basically acceptable, then those functions will
succeed.  But they do not check that a particular hardware device can
actually support the specified speeds--in fact, they don't know which
device you plan to set the speed for.  If you use 'tcsetattr' to set the
speed of a particular device to a value that it cannot handle,
'tcsetattr' returns -1.

   *Portability note:* In the GNU C Library, the functions above accept
speeds measured in bits per second as input, and return speed values
measured in bits per second.  Other libraries require speeds to be
indicated by special codes.  For POSIX.1 portability, you must use one
of the following symbols to represent the speed; their precise numeric
values are system-dependent, but each name has a fixed meaning: 'B110'
stands for 110 bps, 'B300' for 300 bps, and so on.  There is no portable
way to represent any speed but these, but these are the only speeds that
typical serial lines can support.

     B0  B50  B75  B110  B134  B150  B200
     B300  B600  B1200  B1800  B2400  B4800
     B9600  B19200  B38400  B57600  B115200
     B230400  B460800

   BSD defines two additional speed symbols as aliases: 'EXTA' is an
alias for 'B19200' and 'EXTB' is an alias for 'B38400'.  These aliases
are obsolete.


File: libc.info,  Node: Special Characters,  Next: Noncanonical Input,  Prev: Line Speed,  Up: Terminal Modes

17.4.9 Special Characters
-------------------------

In canonical input, the terminal driver recognizes a number of special
characters which perform various control functions.  These include the
ERASE character (usually <DEL>) for editing input, and other editing
characters.  The INTR character (normally 'C-c') for sending a 'SIGINT'
signal, and other signal-raising characters, may be available in either
canonical or noncanonical input mode.  All these characters are
described in this section.

   The particular characters used are specified in the 'c_cc' member of
the 'struct termios' structure.  This member is an array; each element
specifies the character for a particular role.  Each element has a
symbolic constant that stands for the index of that element--for
example, 'VINTR' is the index of the element that specifies the INTR
character, so storing ''='' in 'TERMIOS.c_cc[VINTR]' specifies '=' as
the INTR character.

   On some systems, you can disable a particular special character
function by specifying the value '_POSIX_VDISABLE' for that role.  This
value is unequal to any possible character code.  *Note Options for
Files::, for more information about how to tell whether the operating
system you are using supports '_POSIX_VDISABLE'.

* Menu:

* Editing Characters::          Special characters that terminate lines and
                                  delete text, and other editing functions.
* Signal Characters::           Special characters that send or raise signals
                                  to or for certain classes of processes.
* Start/Stop Characters::       Special characters that suspend or resume
                                  suspended output.
* Other Special::		Other special characters for BSD systems:
				  they can discard output, and print status.


File: libc.info,  Node: Editing Characters,  Next: Signal Characters,  Up: Special Characters

17.4.9.1 Characters for Input Editing
.....................................

These special characters are active only in canonical input mode.  *Note
Canonical or Not::.

 -- Macro: int VEOF
     This is the subscript for the EOF character in the special control
     character array.  'TERMIOS.c_cc[VEOF]' holds the character itself.

     The EOF character is recognized only in canonical input mode.  It
     acts as a line terminator in the same way as a newline character,
     but if the EOF character is typed at the beginning of a line it
     causes 'read' to return a byte count of zero, indicating
     end-of-file.  The EOF character itself is discarded.

     Usually, the EOF character is 'C-d'.

 -- Macro: int VEOL
     This is the subscript for the EOL character in the special control
     character array.  'TERMIOS.c_cc[VEOL]' holds the character itself.

     The EOL character is recognized only in canonical input mode.  It
     acts as a line terminator, just like a newline character.  The EOL
     character is not discarded; it is read as the last character in the
     input line.

     You don't need to use the EOL character to make <RET> end a line.
     Just set the ICRNL flag.  In fact, this is the default state of
     affairs.

 -- Macro: int VEOL2
     This is the subscript for the EOL2 character in the special control
     character array.  'TERMIOS.c_cc[VEOL2]' holds the character itself.

     The EOL2 character works just like the EOL character (see above),
     but it can be a different character.  Thus, you can specify two
     characters to terminate an input line, by setting EOL to one of
     them and EOL2 to the other.

     The EOL2 character is a BSD extension; it exists only on BSD
     systems and GNU/Linux and GNU/Hurd systems.

 -- Macro: int VERASE
     This is the subscript for the ERASE character in the special
     control character array.  'TERMIOS.c_cc[VERASE]' holds the
     character itself.

     The ERASE character is recognized only in canonical input mode.
     When the user types the erase character, the previous character
     typed is discarded.  (If the terminal generates multibyte character
     sequences, this may cause more than one byte of input to be
     discarded.)  This cannot be used to erase past the beginning of the
     current line of text.  The ERASE character itself is discarded.

     Usually, the ERASE character is <DEL>.

 -- Macro: int VWERASE
     This is the subscript for the WERASE character in the special
     control character array.  'TERMIOS.c_cc[VWERASE]' holds the
     character itself.

     The WERASE character is recognized only in canonical mode.  It
     erases an entire word of prior input, and any whitespace after it;
     whitespace characters before the word are not erased.

     The definition of a "word" depends on the setting of the
     'ALTWERASE' mode; *note Local Modes::.

     If the 'ALTWERASE' mode is not set, a word is defined as a sequence
     of any characters except space or tab.

     If the 'ALTWERASE' mode is set, a word is defined as a sequence of
     characters containing only letters, numbers, and underscores,
     optionally followed by one character that is not a letter, number,
     or underscore.

     The WERASE character is usually 'C-w'.

     This is a BSD extension.

 -- Macro: int VKILL
     This is the subscript for the KILL character in the special control
     character array.  'TERMIOS.c_cc[VKILL]' holds the character itself.

     The KILL character is recognized only in canonical input mode.
     When the user types the kill character, the entire contents of the
     current line of input are discarded.  The kill character itself is
     discarded too.

     The KILL character is usually 'C-u'.

 -- Macro: int VREPRINT
     This is the subscript for the REPRINT character in the special
     control character array.  'TERMIOS.c_cc[VREPRINT]' holds the
     character itself.

     The REPRINT character is recognized only in canonical mode.  It
     reprints the current input line.  If some asynchronous output has
     come while you are typing, this lets you see the line you are
     typing clearly again.

     The REPRINT character is usually 'C-r'.

     This is a BSD extension.


File: libc.info,  Node: Signal Characters,  Next: Start/Stop Characters,  Prev: Editing Characters,  Up: Special Characters

17.4.9.2 Characters that Cause Signals
......................................

These special characters may be active in either canonical or
noncanonical input mode, but only when the 'ISIG' flag is set (*note
Local Modes::).

 -- Macro: int VINTR
     This is the subscript for the INTR character in the special control
     character array.  'TERMIOS.c_cc[VINTR]' holds the character itself.

     The INTR (interrupt) character raises a 'SIGINT' signal for all
     processes in the foreground job associated with the terminal.  The
     INTR character itself is then discarded.  *Note Signal Handling::,
     for more information about signals.

     Typically, the INTR character is 'C-c'.

 -- Macro: int VQUIT
     This is the subscript for the QUIT character in the special control
     character array.  'TERMIOS.c_cc[VQUIT]' holds the character itself.

     The QUIT character raises a 'SIGQUIT' signal for all processes in
     the foreground job associated with the terminal.  The QUIT
     character itself is then discarded.  *Note Signal Handling::, for
     more information about signals.

     Typically, the QUIT character is 'C-\'.

 -- Macro: int VSUSP
     This is the subscript for the SUSP character in the special control
     character array.  'TERMIOS.c_cc[VSUSP]' holds the character itself.

     The SUSP (suspend) character is recognized only if the
     implementation supports job control (*note Job Control::).  It
     causes a 'SIGTSTP' signal to be sent to all processes in the
     foreground job associated with the terminal.  The SUSP character
     itself is then discarded.  *Note Signal Handling::, for more
     information about signals.

     Typically, the SUSP character is 'C-z'.

   Few applications disable the normal interpretation of the SUSP
character.  If your program does this, it should provide some other
mechanism for the user to stop the job.  When the user invokes this
mechanism, the program should send a 'SIGTSTP' signal to the process
group of the process, not just to the process itself.  *Note Signaling
Another Process::.

 -- Macro: int VDSUSP
     This is the subscript for the DSUSP character in the special
     control character array.  'TERMIOS.c_cc[VDSUSP]' holds the
     character itself.

     The DSUSP (suspend) character is recognized only if the
     implementation supports job control (*note Job Control::).  It
     sends a 'SIGTSTP' signal, like the SUSP character, but not right
     away--only when the program tries to read it as input.  Not all
     systems with job control support DSUSP; only BSD-compatible systems
     (including GNU/Hurd systems).

     *Note Signal Handling::, for more information about signals.

     Typically, the DSUSP character is 'C-y'.


File: libc.info,  Node: Start/Stop Characters,  Next: Other Special,  Prev: Signal Characters,  Up: Special Characters

17.4.9.3 Special Characters for Flow Control
............................................

These special characters may be active in either canonical or
noncanonical input mode, but their use is controlled by the flags 'IXON'
and 'IXOFF' (*note Input Modes::).

 -- Macro: int VSTART
     This is the subscript for the START character in the special
     control character array.  'TERMIOS.c_cc[VSTART]' holds the
     character itself.

     The START character is used to support the 'IXON' and 'IXOFF' input
     modes.  If 'IXON' is set, receiving a START character resumes
     suspended output; the START character itself is discarded.  If
     'IXANY' is set, receiving any character at all resumes suspended
     output; the resuming character is not discarded unless it is the
     START character.  'IXOFF' is set, the system may also transmit
     START characters to the terminal.

     The usual value for the START character is 'C-q'.  You may not be
     able to change this value--the hardware may insist on using 'C-q'
     regardless of what you specify.

 -- Macro: int VSTOP
     This is the subscript for the STOP character in the special control
     character array.  'TERMIOS.c_cc[VSTOP]' holds the character itself.

     The STOP character is used to support the 'IXON' and 'IXOFF' input
     modes.  If 'IXON' is set, receiving a STOP character causes output
     to be suspended; the STOP character itself is discarded.  If
     'IXOFF' is set, the system may also transmit STOP characters to the
     terminal, to prevent the input queue from overflowing.

     The usual value for the STOP character is 'C-s'.  You may not be
     able to change this value--the hardware may insist on using 'C-s'
     regardless of what you specify.


File: libc.info,  Node: Other Special,  Prev: Start/Stop Characters,  Up: Special Characters

17.4.9.4 Other Special Characters
.................................

 -- Macro: int VLNEXT
     This is the subscript for the LNEXT character in the special
     control character array.  'TERMIOS.c_cc[VLNEXT]' holds the
     character itself.

     The LNEXT character is recognized only when 'IEXTEN' is set, but in
     both canonical and noncanonical mode.  It disables any special
     significance of the next character the user types.  Even if the
     character would normally perform some editing function or generate
     a signal, it is read as a plain character.  This is the analogue of
     the 'C-q' command in Emacs.  "LNEXT" stands for "literal next."

     The LNEXT character is usually 'C-v'.

     This character is available on BSD systems and GNU/Linux and
     GNU/Hurd systems.

 -- Macro: int VDISCARD
     This is the subscript for the DISCARD character in the special
     control character array.  'TERMIOS.c_cc[VDISCARD]' holds the
     character itself.

     The DISCARD character is recognized only when 'IEXTEN' is set, but
     in both canonical and noncanonical mode.  Its effect is to toggle
     the discard-output flag.  When this flag is set, all program output
     is discarded.  Setting the flag also discards all output currently
     in the output buffer.  Typing any other character resets the flag.

     This character is available on BSD systems and GNU/Linux and
     GNU/Hurd systems.

 -- Macro: int VSTATUS
     This is the subscript for the STATUS character in the special
     control character array.  'TERMIOS.c_cc[VSTATUS]' holds the
     character itself.

     The STATUS character's effect is to print out a status message
     about how the current process is running.

     The STATUS character is recognized only in canonical mode, and only
     if 'NOKERNINFO' is not set.

     This character is available only on BSD systems and GNU/Hurd
     systems.


File: libc.info,  Node: Noncanonical Input,  Prev: Special Characters,  Up: Terminal Modes

17.4.10 Noncanonical Input
--------------------------

In noncanonical input mode, the special editing characters such as ERASE
and KILL are ignored.  The system facilities for the user to edit input
are disabled in noncanonical mode, so that all input characters (unless
they are special for signal or flow-control purposes) are passed to the
application program exactly as typed.  It is up to the application
program to give the user ways to edit the input, if appropriate.

   Noncanonical mode offers special parameters called MIN and TIME for
controlling whether and how long to wait for input to be available.  You
can even use them to avoid ever waiting--to return immediately with
whatever input is available, or with no input.

   The MIN and TIME are stored in elements of the 'c_cc' array, which is
a member of the 'struct termios' structure.  Each element of this array
has a particular role, and each element has a symbolic constant that
stands for the index of that element.  'VMIN' and 'VMAX' are the names
for the indices in the array of the MIN and TIME slots.

 -- Macro: int VMIN
     This is the subscript for the MIN slot in the 'c_cc' array.  Thus,
     'TERMIOS.c_cc[VMIN]' is the value itself.

     The MIN slot is only meaningful in noncanonical input mode; it
     specifies the minimum number of bytes that must be available in the
     input queue in order for 'read' to return.

 -- Macro: int VTIME
     This is the subscript for the TIME slot in the 'c_cc' array.  Thus,
     'TERMIOS.c_cc[VTIME]' is the value itself.

     The TIME slot is only meaningful in noncanonical input mode; it
     specifies how long to wait for input before returning, in units of
     0.1 seconds.

   The MIN and TIME values interact to determine the criterion for when
'read' should return; their precise meanings depend on which of them are
nonzero.  There are four possible cases:

   * Both TIME and MIN are nonzero.

     In this case, TIME specifies how long to wait after each input
     character to see if more input arrives.  After the first character
     received, 'read' keeps waiting until either MIN bytes have arrived
     in all, or TIME elapses with no further input.

     'read' always blocks until the first character arrives, even if
     TIME elapses first.  'read' can return more than MIN characters if
     more than MIN happen to be in the queue.

   * Both MIN and TIME are zero.

     In this case, 'read' always returns immediately with as many
     characters as are available in the queue, up to the number
     requested.  If no input is immediately available, 'read' returns a
     value of zero.

   * MIN is zero but TIME has a nonzero value.

     In this case, 'read' waits for time TIME for input to become
     available; the availability of a single byte is enough to satisfy
     the read request and cause 'read' to return.  When it returns, it
     returns as many characters as are available, up to the number
     requested.  If no input is available before the timer expires,
     'read' returns a value of zero.

   * TIME is zero but MIN has a nonzero value.

     In this case, 'read' waits until at least MIN bytes are available
     in the queue.  At that time, 'read' returns as many characters as
     are available, up to the number requested.  'read' can return more
     than MIN characters if more than MIN happen to be in the queue.

   What happens if MIN is 50 and you ask to read just 10 bytes?
Normally, 'read' waits until there are 50 bytes in the buffer (or, more
generally, the wait condition described above is satisfied), and then
reads 10 of them, leaving the other 40 buffered in the operating system
for a subsequent call to 'read'.

   *Portability note:* On some systems, the MIN and TIME slots are
actually the same as the EOF and EOL slots.  This causes no serious
problem because the MIN and TIME slots are used only in noncanonical
input and the EOF and EOL slots are used only in canonical input, but it
isn't very clean.  The GNU C Library allocates separate slots for these
uses.

 -- Function: void cfmakeraw (struct termios *TERMIOS-P)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     This function provides an easy way to set up '*TERMIOS-P' for what
     has traditionally been called "raw mode" in BSD. This uses
     noncanonical input, and turns off most processing to give an
     unmodified channel to the terminal.

     It does exactly this:
            TERMIOS-P->c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP
                                          |INLCR|IGNCR|ICRNL|IXON);
            TERMIOS-P->c_oflag &= ~OPOST;
            TERMIOS-P->c_lflag &= ~(ECHO|ECHONL|ICANON|ISIG|IEXTEN);
            TERMIOS-P->c_cflag &= ~(CSIZE|PARENB);
            TERMIOS-P->c_cflag |= CS8;


File: libc.info,  Node: BSD Terminal Modes,  Next: Line Control,  Prev: Terminal Modes,  Up: Low-Level Terminal Interface

17.5 BSD Terminal Modes
=======================

The usual way to get and set terminal modes is with the functions
described in *note Terminal Modes::.  However, on some systems you can
use the BSD-derived functions in this section to do some of the same
thing.  On many systems, these functions do not exist.  Even with the
GNU C Library, the functions simply fail with 'errno' = 'ENOSYS' with
many kernels, including Linux.

   The symbols used in this section are declared in 'sgtty.h'.

 -- Data Type: struct sgttyb
     This structure is an input or output parameter list for 'gtty' and
     'stty'.

     'char sg_ispeed'
          Line speed for input
     'char sg_ospeed'
          Line speed for output
     'char sg_erase'
          Erase character
     'char sg_kill'
          Kill character
     'int sg_flags'
          Various flags

 -- Function: int gtty (int FILEDES, struct sgttyb *ATTRIBUTES)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     This function gets the attributes of a terminal.

     'gtty' sets *ATTRIBUTES to describe the terminal attributes of the
     terminal which is open with file descriptor FILEDES.

 -- Function: int stty (int FILEDES, const struct sgttyb *ATTRIBUTES)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     This function sets the attributes of a terminal.

     'stty' sets the terminal attributes of the terminal which is open
     with file descriptor FILEDES to those described by *FILEDES.


File: libc.info,  Node: Line Control,  Next: Noncanon Example,  Prev: BSD Terminal Modes,  Up: Low-Level Terminal Interface

17.6 Line Control Functions
===========================

These functions perform miscellaneous control actions on terminal
devices.  As regards terminal access, they are treated like doing
output: if any of these functions is used by a background process on its
controlling terminal, normally all processes in the process group are
sent a 'SIGTTOU' signal.  The exception is if the calling process itself
is ignoring or blocking 'SIGTTOU' signals, in which case the operation
is performed and no signal is sent.  *Note Job Control::.

 -- Function: int tcsendbreak (int FILEDES, int DURATION)
     Preliminary: | MT-Unsafe race:tcattr(filedes)/bsd | AS-Unsafe |
     AC-Unsafe corrupt/bsd | *Note POSIX Safety Concepts::.

     This function generates a break condition by transmitting a stream
     of zero bits on the terminal associated with the file descriptor
     FILEDES.  The duration of the break is controlled by the DURATION
     argument.  If zero, the duration is between 0.25 and 0.5 seconds.
     The meaning of a nonzero value depends on the operating system.

     This function does nothing if the terminal is not an asynchronous
     serial data port.

     The return value is normally zero.  In the event of an error, a
     value of -1 is returned.  The following 'errno' error conditions
     are defined for this function:

     'EBADF'
          The FILEDES is not a valid file descriptor.

     'ENOTTY'
          The FILEDES is not associated with a terminal device.

 -- Function: int tcdrain (int FILEDES)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     The 'tcdrain' function waits until all queued output to the
     terminal FILEDES has been transmitted.

     This function is a cancellation point in multi-threaded programs.
     This is a problem if the thread allocates some resources (like
     memory, file descriptors, semaphores or whatever) at the time
     'tcdrain' is called.  If the thread gets canceled these resources
     stay allocated until the program ends.  To avoid this calls to
     'tcdrain' should be protected using cancellation handlers.

     The return value is normally zero.  In the event of an error, a
     value of -1 is returned.  The following 'errno' error conditions
     are defined for this function:

     'EBADF'
          The FILEDES is not a valid file descriptor.

     'ENOTTY'
          The FILEDES is not associated with a terminal device.

     'EINTR'
          The operation was interrupted by delivery of a signal.  *Note
          Interrupted Primitives::.

 -- Function: int tcflush (int FILEDES, int QUEUE)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     The 'tcflush' function is used to clear the input and/or output
     queues associated with the terminal file FILEDES.  The QUEUE
     argument specifies which queue(s) to clear, and can be one of the
     following values:

     'TCIFLUSH'

          Clear any input data received, but not yet read.

     'TCOFLUSH'

          Clear any output data written, but not yet transmitted.

     'TCIOFLUSH'

          Clear both queued input and output.

     The return value is normally zero.  In the event of an error, a
     value of -1 is returned.  The following 'errno' error conditions
     are defined for this function:

     'EBADF'
          The FILEDES is not a valid file descriptor.

     'ENOTTY'
          The FILEDES is not associated with a terminal device.

     'EINVAL'
          A bad value was supplied as the QUEUE argument.

     It is unfortunate that this function is named 'tcflush', because
     the term "flush" is normally used for quite another
     operation--waiting until all output is transmitted--and using it
     for discarding input or output would be confusing.  Unfortunately,
     the name 'tcflush' comes from POSIX and we cannot change it.

 -- Function: int tcflow (int FILEDES, int ACTION)
     Preliminary: | MT-Unsafe race:tcattr(filedes)/bsd | AS-Unsafe |
     AC-Safe | *Note POSIX Safety Concepts::.

     The 'tcflow' function is used to perform operations relating to
     XON/XOFF flow control on the terminal file specified by FILEDES.

     The ACTION argument specifies what operation to perform, and can be
     one of the following values:

     'TCOOFF'
          Suspend transmission of output.

     'TCOON'
          Restart transmission of output.

     'TCIOFF'
          Transmit a STOP character.

     'TCION'
          Transmit a START character.

     For more information about the STOP and START characters, see *note
     Special Characters::.

     The return value is normally zero.  In the event of an error, a
     value of -1 is returned.  The following 'errno' error conditions
     are defined for this function:

     'EBADF'
          The FILEDES is not a valid file descriptor.

     'ENOTTY'
          The FILEDES is not associated with a terminal device.

     'EINVAL'
          A bad value was supplied as the ACTION argument.


File: libc.info,  Node: Noncanon Example,  Next: Pseudo-Terminals,  Prev: Line Control,  Up: Low-Level Terminal Interface

17.7 Noncanonical Mode Example
==============================

Here is an example program that shows how you can set up a terminal
device to read single characters in noncanonical input mode, without
echo.


     #include <unistd.h>
     #include <stdio.h>
     #include <stdlib.h>
     #include <termios.h>

     /* Use this variable to remember original terminal attributes. */

     struct termios saved_attributes;

     void
     reset_input_mode (void)
     {
       tcsetattr (STDIN_FILENO, TCSANOW, &saved_attributes);
     }

     void
     set_input_mode (void)
     {
       struct termios tattr;
       char *name;

       /* Make sure stdin is a terminal. */
       if (!isatty (STDIN_FILENO))
         {
           fprintf (stderr, "Not a terminal.\n");
           exit (EXIT_FAILURE);
         }

       /* Save the terminal attributes so we can restore them later. */
       tcgetattr (STDIN_FILENO, &saved_attributes);
       atexit (reset_input_mode);

       /* Set the funny terminal modes. */
       tcgetattr (STDIN_FILENO, &tattr);
       tattr.c_lflag &= ~(ICANON|ECHO); /* Clear ICANON and ECHO. */
       tattr.c_cc[VMIN] = 1;
       tattr.c_cc[VTIME] = 0;
       tcsetattr (STDIN_FILENO, TCSAFLUSH, &tattr);
     }

     int
     main (void)
     {
       char c;

       set_input_mode ();

       while (1)
         {
           read (STDIN_FILENO, &c, 1);
           if (c == '\004')          /* 'C-d' */
             break;
           else
             putchar (c);
         }

       return EXIT_SUCCESS;
     }

   This program is careful to restore the original terminal modes before
exiting or terminating with a signal.  It uses the 'atexit' function
(*note Cleanups on Exit::) to make sure this is done by 'exit'.

   The shell is supposed to take care of resetting the terminal modes
when a process is stopped or continued; see *note Job Control::.  But
some existing shells do not actually do this, so you may wish to
establish handlers for job control signals that reset terminal modes.
The above example does so.


File: libc.info,  Node: Pseudo-Terminals,  Prev: Noncanon Example,  Up: Low-Level Terminal Interface

17.8 Pseudo-Terminals
=====================

A "pseudo-terminal" is a special interprocess communication channel that
acts like a terminal.  One end of the channel is called the "master"
side or "master pseudo-terminal device", the other side is called the
"slave" side.  Data written to the master side is received by the slave
side as if it was the result of a user typing at an ordinary terminal,
and data written to the slave side is sent to the master side as if it
was written on an ordinary terminal.

   Pseudo terminals are the way programs like 'xterm' and 'emacs'
implement their terminal emulation functionality.

* Menu:

* Allocation::             Allocating a pseudo terminal.
* Pseudo-Terminal Pairs::  How to open both sides of a
                            pseudo-terminal in a single operation.


File: libc.info,  Node: Allocation,  Next: Pseudo-Terminal Pairs,  Up: Pseudo-Terminals

17.8.1 Allocating Pseudo-Terminals
----------------------------------

This subsection describes functions for allocating a pseudo-terminal,
and for making this pseudo-terminal available for actual use.  These
functions are declared in the header file 'stdlib.h'.

 -- Function: int getpt (void)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe fd | *Note POSIX Safety
     Concepts::.

     The 'getpt' function returns a new file descriptor for the next
     available master pseudo-terminal.  The normal return value from
     'getpt' is a non-negative integer file descriptor.  In the case of
     an error, a value of -1 is returned instead.  The following 'errno'
     conditions are defined for this function:

     'ENOENT'
          There are no free master pseudo-terminals available.

     This function is a GNU extension.

 -- Function: int grantpt (int FILEDES)
     Preliminary: | MT-Safe locale | AS-Unsafe dlopen plugin heap lock |
     AC-Unsafe corrupt lock fd mem | *Note POSIX Safety Concepts::.

     The 'grantpt' function changes the ownership and access permission
     of the slave pseudo-terminal device corresponding to the master
     pseudo-terminal device associated with the file descriptor FILEDES.
     The owner is set from the real user ID of the calling process
     (*note Process Persona::), and the group is set to a special group
     (typically "tty") or from the real group ID of the calling process.
     The access permission is set such that the file is both readable
     and writable by the owner and only writable by the group.

     On some systems this function is implemented by invoking a special
     'setuid' root program (*note How Change Persona::).  As a
     consequence, installing a signal handler for the 'SIGCHLD' signal
     (*note Job Control Signals::) may interfere with a call to
     'grantpt'.

     The normal return value from 'grantpt' is 0; a value of -1 is
     returned in case of failure.  The following 'errno' error
     conditions are defined for this function:

     'EBADF'
          The FILEDES argument is not a valid file descriptor.

     'EINVAL'
          The FILEDES argument is not associated with a master
          pseudo-terminal device.

     'EACCES'
          The slave pseudo-terminal device corresponding to the master
          associated with FILEDES could not be accessed.

 -- Function: int unlockpt (int FILEDES)
     Preliminary: | MT-Safe | AS-Unsafe heap/bsd | AC-Unsafe mem fd |
     *Note POSIX Safety Concepts::.

     The 'unlockpt' function unlocks the slave pseudo-terminal device
     corresponding to the master pseudo-terminal device associated with
     the file descriptor FILEDES.  On many systems, the slave can only
     be opened after unlocking, so portable applications should always
     call 'unlockpt' before trying to open the slave.

     The normal return value from 'unlockpt' is 0; a value of -1 is
     returned in case of failure.  The following 'errno' error
     conditions are defined for this function:

     'EBADF'
          The FILEDES argument is not a valid file descriptor.

     'EINVAL'
          The FILEDES argument is not associated with a master
          pseudo-terminal device.

 -- Function: char * ptsname (int FILEDES)
     Preliminary: | MT-Unsafe race:ptsname | AS-Unsafe heap/bsd |
     AC-Unsafe mem fd | *Note POSIX Safety Concepts::.

     If the file descriptor FILEDES is associated with a master
     pseudo-terminal device, the 'ptsname' function returns a pointer to
     a statically-allocated, null-terminated string containing the file
     name of the associated slave pseudo-terminal file.  This string
     might be overwritten by subsequent calls to 'ptsname'.

 -- Function: int ptsname_r (int FILEDES, char *BUF, size_t LEN)
     Preliminary: | MT-Safe | AS-Unsafe heap/bsd | AC-Unsafe mem fd |
     *Note POSIX Safety Concepts::.

     The 'ptsname_r' function is similar to the 'ptsname' function
     except that it places its result into the user-specified buffer
     starting at BUF with length LEN.

     This function is a GNU extension.

   *Portability Note:* On System V derived systems, the file returned by
the 'ptsname' and 'ptsname_r' functions may be STREAMS-based, and
therefore require additional processing after opening before it actually
behaves as a pseudo terminal.

   Typical usage of these functions is illustrated by the following
example:
     int
     open_pty_pair (int *amaster, int *aslave)
     {
       int master, slave;
       char *name;

       master = getpt ();
       if (master < 0)
         return 0;

       if (grantpt (master) < 0 || unlockpt (master) < 0)
         goto close_master;
       name = ptsname (master);
       if (name == NULL)
         goto close_master;

       slave = open (name, O_RDWR);
       if (slave == -1)
         goto close_master;

       if (isastream (slave))
         {
           if (ioctl (slave, I_PUSH, "ptem") < 0
               || ioctl (slave, I_PUSH, "ldterm") < 0)
             goto close_slave;
         }

       *amaster = master;
       *aslave = slave;
       return 1;

     close_slave:
       close (slave);

     close_master:
       close (master);
       return 0;
     }


File: libc.info,  Node: Pseudo-Terminal Pairs,  Prev: Allocation,  Up: Pseudo-Terminals

17.8.2 Opening a Pseudo-Terminal Pair
-------------------------------------

These functions, derived from BSD, are available in the separate
'libutil' library, and declared in 'pty.h'.

 -- Function: int openpty (int *AMASTER, int *ASLAVE, char *NAME, const
          struct termios *TERMP, const struct winsize *WINP)
     Preliminary: | MT-Safe locale | AS-Unsafe dlopen plugin heap lock |
     AC-Unsafe corrupt lock fd mem | *Note POSIX Safety Concepts::.

     This function allocates and opens a pseudo-terminal pair, returning
     the file descriptor for the master in *AMASTER, and the file
     descriptor for the slave in *ASLAVE.  If the argument NAME is not a
     null pointer, the file name of the slave pseudo-terminal device is
     stored in '*name'.  If TERMP is not a null pointer, the terminal
     attributes of the slave are set to the ones specified in the
     structure that TERMP points to (*note Terminal Modes::).  Likewise,
     if the WINP is not a null pointer, the screen size of the slave is
     set to the values specified in the structure that WINP points to.

     The normal return value from 'openpty' is 0; a value of -1 is
     returned in case of failure.  The following 'errno' conditions are
     defined for this function:

     'ENOENT'
          There are no free pseudo-terminal pairs available.

     *Warning:* Using the 'openpty' function with NAME not set to 'NULL'
     is *very dangerous* because it provides no protection against
     overflowing the string NAME.  You should use the 'ttyname' function
     on the file descriptor returned in *SLAVE to find out the file name
     of the slave pseudo-terminal device instead.

 -- Function: int forkpty (int *AMASTER, char *NAME, const struct
          termios *TERMP, const struct winsize *WINP)
     Preliminary: | MT-Safe locale | AS-Unsafe dlopen plugin heap lock |
     AC-Unsafe corrupt lock fd mem | *Note POSIX Safety Concepts::.

     This function is similar to the 'openpty' function, but in
     addition, forks a new process (*note Creating a Process::) and
     makes the newly opened slave pseudo-terminal device the controlling
     terminal (*note Controlling Terminal::) for the child process.

     If the operation is successful, there are then both parent and
     child processes and both see 'forkpty' return, but with different
     values: it returns a value of 0 in the child process and returns
     the child's process ID in the parent process.

     If the allocation of a pseudo-terminal pair or the process creation
     failed, 'forkpty' returns a value of -1 in the parent process.

     *Warning:* The 'forkpty' function has the same problems with
     respect to the NAME argument as 'openpty'.


File: libc.info,  Node: Syslog,  Next: Mathematics,  Prev: Low-Level Terminal Interface,  Up: Top

18 Syslog
*********

This chapter describes facilities for issuing and logging messages of
system administration interest.  This chapter has nothing to do with
programs issuing messages to their own users or keeping private logs
(One would typically do that with the facilities described in *note I/O
on Streams::).

   Most systems have a facility called "Syslog" that allows programs to
submit messages of interest to system administrators and can be
configured to pass these messages on in various ways, such as printing
on the console, mailing to a particular person, or recording in a log
file for future reference.

   A program uses the facilities in this chapter to submit such
messages.

* Menu:

* Overview of Syslog::           Overview of a system's Syslog facility
* Submitting Syslog Messages::   Functions to submit messages to Syslog


File: libc.info,  Node: Overview of Syslog,  Next: Submitting Syslog Messages,  Up: Syslog

18.1 Overview of Syslog
=======================

System administrators have to deal with lots of different kinds of
messages from a plethora of subsystems within each system, and usually
lots of systems as well.  For example, an FTP server might report every
connection it gets.  The kernel might report hardware failures on a disk
drive.  A DNS server might report usage statistics at regular intervals.

   Some of these messages need to be brought to a system administrator's
attention immediately.  And it may not be just any system administrator
- there may be a particular system administrator who deals with a
particular kind of message.  Other messages just need to be recorded for
future reference if there is a problem.  Still others may need to have
information extracted from them by an automated process that generates
monthly reports.

   To deal with these messages, most Unix systems have a facility called
"Syslog."  It is generally based on a daemon called "Syslogd" Syslogd
listens for messages on a Unix domain socket named '/dev/log'.  Based on
classification information in the messages and its configuration file
(usually '/etc/syslog.conf'), Syslogd routes them in various ways.  Some
of the popular routings are:

   * Write to the system console
   * Mail to a specific user
   * Write to a log file
   * Pass to another daemon
   * Discard

   Syslogd can also handle messages from other systems.  It listens on
the 'syslog' UDP port as well as the local socket for messages.

   Syslog can handle messages from the kernel itself.  But the kernel
doesn't write to '/dev/log'; rather, another daemon (sometimes called
"Klogd") extracts messages from the kernel and passes them on to Syslog
as any other process would (and it properly identifies them as messages
from the kernel).

   Syslog can even handle messages that the kernel issued before Syslogd
or Klogd was running.  A Linux kernel, for example, stores startup
messages in a kernel message ring and they are normally still there when
Klogd later starts up.  Assuming Syslogd is running by the time Klogd
starts, Klogd then passes everything in the message ring to it.

   In order to classify messages for disposition, Syslog requires any
process that submits a message to it to provide two pieces of
classification information with it:

facility
     This identifies who submitted the message.  There are a small
     number of facilities defined.  The kernel, the mail subsystem, and
     an FTP server are examples of recognized facilities.  For the
     complete list, *Note syslog; vsyslog::.  Keep in mind that these
     are essentially arbitrary classifications.  "Mail subsystem"
     doesn't have any more meaning than the system administrator gives
     to it.

priority
     This tells how important the content of the message is.  Examples
     of defined priority values are: debug, informational, warning,
     critical.  For the complete list, see *note syslog; vsyslog::.
     Except for the fact that the priorities have a defined order, the
     meaning of each of these priorities is entirely determined by the
     system administrator.

   A "facility/priority" is a number that indicates both the facility
and the priority.

   *Warning:* This terminology is not universal.  Some people use
"level" to refer to the priority and "priority" to refer to the
combination of facility and priority.  A Linux kernel has a concept of a
message "level," which corresponds both to a Syslog priority and to a
Syslog facility/priority (It can be both because the facility code for
the kernel is zero, and that makes priority and facility/priority the
same value).

   The GNU C Library provides functions to submit messages to Syslog.
They do it by writing to the '/dev/log' socket.  *Note Submitting Syslog
Messages::.

   The GNU C Library functions only work to submit messages to the
Syslog facility on the same system.  To submit a message to the Syslog
facility on another system, use the socket I/O functions to write a UDP
datagram to the 'syslog' UDP port on that system.  *Note Sockets::.


File: libc.info,  Node: Submitting Syslog Messages,  Prev: Overview of Syslog,  Up: Syslog

18.2 Submitting Syslog Messages
===============================

The GNU C Library provides functions to submit messages to the Syslog
facility:

* Menu:

* openlog::                      Open connection to Syslog
* syslog; vsyslog::              Submit message to Syslog
* closelog::                     Close connection to Syslog
* setlogmask::                   Cause certain messages to be ignored
* Syslog Example::               Example of all of the above

   These functions only work to submit messages to the Syslog facility
on the same system.  To submit a message to the Syslog facility on
another system, use the socket I/O functions to write a UDP datagram to
the 'syslog' UDP port on that system.  *Note Sockets::.


File: libc.info,  Node: openlog,  Next: syslog; vsyslog,  Up: Submitting Syslog Messages

18.2.1 openlog
--------------

The symbols referred to in this section are declared in the file
'syslog.h'.

 -- Function: void openlog (const char *IDENT, int OPTION, int FACILITY)
     Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock fd | *Note
     POSIX Safety Concepts::.

     'openlog' opens or reopens a connection to Syslog in preparation
     for submitting messages.

     IDENT is an arbitrary identification string which future 'syslog'
     invocations will prefix to each message.  This is intended to
     identify the source of the message, and people conventionally set
     it to the name of the program that will submit the messages.

     If IDENT is NULL, or if 'openlog' is not called, the default
     identification string used in Syslog messages will be the program
     name, taken from argv[0].

     Please note that the string pointer IDENT will be retained
     internally by the Syslog routines.  You must not free the memory
     that IDENT points to.  It is also dangerous to pass a reference to
     an automatic variable since leaving the scope would mean ending the
     lifetime of the variable.  If you want to change the IDENT string,
     you must call 'openlog' again; overwriting the string pointed to by
     IDENT is not thread-safe.

     You can cause the Syslog routines to drop the reference to IDENT
     and go back to the default string (the program name taken from
     argv[0]), by calling 'closelog': *Note closelog::.

     In particular, if you are writing code for a shared library that
     might get loaded and then unloaded (e.g.  a PAM module), and you
     use 'openlog', you must call 'closelog' before any point where your
     library might get unloaded, as in this example:

          #include <syslog.h>

          void
          shared_library_function (void)
          {
            openlog ("mylibrary", option, priority);

            syslog (LOG_INFO, "shared library has been invoked");

            closelog ();
          }

     Without the call to 'closelog', future invocations of 'syslog' by
     the program using the shared library may crash, if the library gets
     unloaded and the memory containing the string '"mylibrary"' becomes
     unmapped.  This is a limitation of the BSD syslog interface.

     'openlog' may or may not open the '/dev/log' socket, depending on
     OPTION.  If it does, it tries to open it and connect it as a stream
     socket.  If that doesn't work, it tries to open it and connect it
     as a datagram socket.  The socket has the "Close on Exec"
     attribute, so the kernel will close it if the process performs an
     exec.

     You don't have to use 'openlog'.  If you call 'syslog' without
     having called 'openlog', 'syslog' just opens the connection
     implicitly and uses defaults for the information in IDENT and
     OPTIONS.

     OPTIONS is a bit string, with the bits as defined by the following
     single bit masks:

     'LOG_PERROR'
          If on, 'openlog' sets up the connection so that any 'syslog'
          on this connection writes its message to the calling process'
          Standard Error stream in addition to submitting it to Syslog.
          If off, 'syslog' does not write the message to Standard Error.

     'LOG_CONS'
          If on, 'openlog' sets up the connection so that a 'syslog' on
          this connection that fails to submit a message to Syslog
          writes the message instead to system console.  If off,
          'syslog' does not write to the system console (but of course
          Syslog may write messages it receives to the console).

     'LOG_PID'
          When on, 'openlog' sets up the connection so that a 'syslog'
          on this connection inserts the calling process' Process ID
          (PID) into the message.  When off, 'openlog' does not insert
          the PID.

     'LOG_NDELAY'
          When on, 'openlog' opens and connects the '/dev/log' socket.
          When off, a future 'syslog' call must open and connect the
          socket.

          *Portability note:* In early systems, the sense of this bit
          was exactly the opposite.

     'LOG_ODELAY'
          This bit does nothing.  It exists for backward compatibility.

     If any other bit in OPTIONS is on, the result is undefined.

     FACILITY is the default facility code for this connection.  A
     'syslog' on this connection that specifies default facility causes
     this facility to be associated with the message.  See 'syslog' for
     possible values.  A value of zero means the default default, which
     is 'LOG_USER'.

     If a Syslog connection is already open when you call 'openlog',
     'openlog' "reopens" the connection.  Reopening is like opening
     except that if you specify zero for the default facility code, the
     default facility code simply remains unchanged and if you specify
     LOG_NDELAY and the socket is already open and connected, 'openlog'
     just leaves it that way.


File: libc.info,  Node: syslog; vsyslog,  Next: closelog,  Prev: openlog,  Up: Submitting Syslog Messages

18.2.2 syslog, vsyslog
----------------------

The symbols referred to in this section are declared in the file
'syslog.h'.

 -- Function: void syslog (int FACILITY_PRIORITY, const char *FORMAT,
          ...)
     Preliminary: | MT-Safe env locale | AS-Unsafe corrupt heap lock
     dlopen | AC-Unsafe corrupt lock mem fd | *Note POSIX Safety
     Concepts::.

     'syslog' submits a message to the Syslog facility.  It does this by
     writing to the Unix domain socket '/dev/log'.

     'syslog' submits the message with the facility and priority
     indicated by FACILITY_PRIORITY.  The macro 'LOG_MAKEPRI' generates
     a facility/priority from a facility and a priority, as in the
     following example:

          LOG_MAKEPRI(LOG_USER, LOG_WARNING)

     The possible values for the facility code are (macros):

     'LOG_USER'
          A miscellaneous user process
     'LOG_MAIL'
          Mail
     'LOG_DAEMON'
          A miscellaneous system daemon
     'LOG_AUTH'
          Security (authorization)
     'LOG_SYSLOG'
          Syslog
     'LOG_LPR'
          Central printer
     'LOG_NEWS'
          Network news (e.g.  Usenet)
     'LOG_UUCP'
          UUCP
     'LOG_CRON'
          Cron and At
     'LOG_AUTHPRIV'
          Private security (authorization)
     'LOG_FTP'
          Ftp server
     'LOG_LOCAL0'
          Locally defined
     'LOG_LOCAL1'
          Locally defined
     'LOG_LOCAL2'
          Locally defined
     'LOG_LOCAL3'
          Locally defined
     'LOG_LOCAL4'
          Locally defined
     'LOG_LOCAL5'
          Locally defined
     'LOG_LOCAL6'
          Locally defined
     'LOG_LOCAL7'
          Locally defined

     Results are undefined if the facility code is anything else.

     *NB:* 'syslog' recognizes one other facility code: that of the
     kernel.  But you can't specify that facility code with these
     functions.  If you try, it looks the same to 'syslog' as if you are
     requesting the default facility.  But you wouldn't want to anyway,
     because any program that uses the GNU C Library is not the kernel.

     You can use just a priority code as FACILITY_PRIORITY.  In that
     case, 'syslog' assumes the default facility established when the
     Syslog connection was opened.  *Note Syslog Example::.

     The possible values for the priority code are (macros):

     'LOG_EMERG'
          The message says the system is unusable.
     'LOG_ALERT'
          Action on the message must be taken immediately.
     'LOG_CRIT'
          The message states a critical condition.
     'LOG_ERR'
          The message describes an error.
     'LOG_WARNING'
          The message is a warning.
     'LOG_NOTICE'
          The message describes a normal but important event.
     'LOG_INFO'
          The message is purely informational.
     'LOG_DEBUG'
          The message is only for debugging purposes.

     Results are undefined if the priority code is anything else.

     If the process does not presently have a Syslog connection open
     (i.e., it did not call 'openlog'), 'syslog' implicitly opens the
     connection the same as 'openlog' would, with the following defaults
     for information that would otherwise be included in an 'openlog'
     call: The default identification string is the program name.  The
     default default facility is 'LOG_USER'.  The default for all the
     connection options in OPTIONS is as if those bits were off.
     'syslog' leaves the Syslog connection open.

     If the '/dev/log' socket is not open and connected, 'syslog' opens
     and connects it, the same as 'openlog' with the 'LOG_NDELAY' option
     would.

     'syslog' leaves '/dev/log' open and connected unless its attempt to
     send the message failed, in which case 'syslog' closes it (with the
     hope that a future implicit open will restore the Syslog connection
     to a usable state).

     Example:


          #include <syslog.h>
          syslog (LOG_MAKEPRI(LOG_LOCAL1, LOG_ERROR),
                  "Unable to make network connection to %s.  Error=%m", host);


 -- Function: void vsyslog (int FACILITY_PRIORITY, const char *FORMAT,
          va_list ARGLIST)
     Preliminary: | MT-Safe env locale | AS-Unsafe corrupt heap lock
     dlopen | AC-Unsafe corrupt lock mem fd | *Note POSIX Safety
     Concepts::.

     This is functionally identical to 'syslog', with the BSD style
     variable length argument.


File: libc.info,  Node: closelog,  Next: setlogmask,  Prev: syslog; vsyslog,  Up: Submitting Syslog Messages

18.2.3 closelog
---------------

The symbols referred to in this section are declared in the file
'syslog.h'.

 -- Function: void closelog (void)
     Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock fd | *Note
     POSIX Safety Concepts::.

     'closelog' closes the current Syslog connection, if there is one.
     This includes closing the '/dev/log' socket, if it is open.
     'closelog' also sets the identification string for Syslog messages
     back to the default, if 'openlog' was called with a non-NULL
     argument to IDENT.  The default identification string is the
     program name taken from argv[0].

     If you are writing shared library code that uses 'openlog' to
     generate custom syslog output, you should use 'closelog' to drop
     the GNU C Library's internal reference to the IDENT pointer when
     you are done.  Please read the section on 'openlog' for more
     information: *Note openlog::.

     'closelog' does not flush any buffers.  You do not have to call
     'closelog' before re-opening a Syslog connection with 'openlog'.
     Syslog connections are automatically closed on exec or exit.


File: libc.info,  Node: setlogmask,  Next: Syslog Example,  Prev: closelog,  Up: Submitting Syslog Messages

18.2.4 setlogmask
-----------------

The symbols referred to in this section are declared in the file
'syslog.h'.

 -- Function: int setlogmask (int MASK)
     Preliminary: | MT-Unsafe race:LogMask | AS-Unsafe | AC-Safe | *Note
     POSIX Safety Concepts::.

     'setlogmask' sets a mask (the "logmask") that determines which
     future 'syslog' calls shall be ignored.  If a program has not
     called 'setlogmask', 'syslog' doesn't ignore any calls.  You can
     use 'setlogmask' to specify that messages of particular priorities
     shall be ignored in the future.

     A 'setlogmask' call overrides any previous 'setlogmask' call.

     Note that the logmask exists entirely independently of opening and
     closing of Syslog connections.

     Setting the logmask has a similar effect to, but is not the same
     as, configuring Syslog.  The Syslog configuration may cause Syslog
     to discard certain messages it receives, but the logmask causes
     certain messages never to get submitted to Syslog in the first
     place.

     MASK is a bit string with one bit corresponding to each of the
     possible message priorities.  If the bit is on, 'syslog' handles
     messages of that priority normally.  If it is off, 'syslog'
     discards messages of that priority.  Use the message priority
     macros described in *note syslog; vsyslog:: and the 'LOG_MASK' to
     construct an appropriate MASK value, as in this example:

          LOG_MASK(LOG_EMERG) | LOG_MASK(LOG_ERROR)

     or

          ~(LOG_MASK(LOG_INFO))

     There is also a 'LOG_UPTO' macro, which generates a mask with the
     bits on for a certain priority and all priorities above it:

          LOG_UPTO(LOG_ERROR)

     The unfortunate naming of the macro is due to the fact that
     internally, higher numbers are used for lower message priorities.


File: libc.info,  Node: Syslog Example,  Prev: setlogmask,  Up: Submitting Syslog Messages

18.2.5 Syslog Example
---------------------

Here is an example of 'openlog', 'syslog', and 'closelog':

   This example sets the logmask so that debug and informational
messages get discarded without ever reaching Syslog.  So the second
'syslog' in the example does nothing.

     #include <syslog.h>

     setlogmask (LOG_UPTO (LOG_NOTICE));

     openlog ("exampleprog", LOG_CONS | LOG_PID | LOG_NDELAY, LOG_LOCAL1);

     syslog (LOG_NOTICE, "Program started by User %d", getuid ());
     syslog (LOG_INFO, "A tree falls in a forest");

     closelog ();



File: libc.info,  Node: Mathematics,  Next: Arithmetic,  Prev: Syslog,  Up: Top

19 Mathematics
**************

This chapter contains information about functions for performing
mathematical computations, such as trigonometric functions.  Most of
these functions have prototypes declared in the header file 'math.h'.
The complex-valued functions are defined in 'complex.h'.

   All mathematical functions which take a floating-point argument have
three variants, one each for 'double', 'float', and 'long double'
arguments.  The 'double' versions are mostly defined in ISO C89.  The
'float' and 'long double' versions are from the numeric extensions to C
included in ISO C99.

   Which of the three versions of a function should be used depends on
the situation.  For most calculations, the 'float' functions are the
fastest.  On the other hand, the 'long double' functions have the
highest precision.  'double' is somewhere in between.  It is usually
wise to pick the narrowest type that can accommodate your data.  Not all
machines have a distinct 'long double' type; it may be the same as
'double'.

* Menu:

* Mathematical Constants::      Precise numeric values for often-used
                                 constants.
* Trig Functions::              Sine, cosine, tangent, and friends.
* Inverse Trig Functions::      Arcsine, arccosine, etc.
* Exponents and Logarithms::    Also pow and sqrt.
* Hyperbolic Functions::        sinh, cosh, tanh, etc.
* Special Functions::           Bessel, gamma, erf.
* Errors in Math Functions::    Known Maximum Errors in Math Functions.
* Pseudo-Random Numbers::       Functions for generating pseudo-random
				 numbers.
* FP Function Optimizations::   Fast code or small code.


File: libc.info,  Node: Mathematical Constants,  Next: Trig Functions,  Up: Mathematics

19.1 Predefined Mathematical Constants
======================================

The header 'math.h' defines several useful mathematical constants.  All
values are defined as preprocessor macros starting with 'M_'.  The
values provided are:

'M_E'
     The base of natural logarithms.
'M_LOG2E'
     The logarithm to base '2' of 'M_E'.
'M_LOG10E'
     The logarithm to base '10' of 'M_E'.
'M_LN2'
     The natural logarithm of '2'.
'M_LN10'
     The natural logarithm of '10'.
'M_PI'
     Pi, the ratio of a circle's circumference to its diameter.
'M_PI_2'
     Pi divided by two.
'M_PI_4'
     Pi divided by four.
'M_1_PI'
     The reciprocal of pi (1/pi)
'M_2_PI'
     Two times the reciprocal of pi.
'M_2_SQRTPI'
     Two times the reciprocal of the square root of pi.
'M_SQRT2'
     The square root of two.
'M_SQRT1_2'
     The reciprocal of the square root of two (also the square root of
     1/2).

   These constants come from the Unix98 standard and were also available
in 4.4BSD; therefore they are only defined if '_BSD_SOURCE' or
'_XOPEN_SOURCE=500', or a more general feature select macro, is defined.
The default set of features includes these constants.  *Note Feature
Test Macros::.

   All values are of type 'double'.  As an extension, the GNU C Library
also defines these constants with type 'long double'.  The 'long double'
macros have a lowercase 'l' appended to their names: 'M_El', 'M_PIl',
and so forth.  These are only available if '_GNU_SOURCE' is defined.

   _Note:_ Some programs use a constant named 'PI' which has the same
value as 'M_PI'.  This constant is not standard; it may have appeared in
some old AT&T headers, and is mentioned in Stroustrup's book on C++.  It
infringes on the user's name space, so the GNU C Library does not define
it.  Fixing programs written to expect it is simple: replace 'PI' with
'M_PI' throughout, or put '-DPI=M_PI' on the compiler command line.


File: libc.info,  Node: Trig Functions,  Next: Inverse Trig Functions,  Prev: Mathematical Constants,  Up: Mathematics

19.2 Trigonometric Functions
============================

These are the familiar 'sin', 'cos', and 'tan' functions.  The arguments
to all of these functions are in units of radians; recall that pi
radians equals 180 degrees.

   The math library normally defines 'M_PI' to a 'double' approximation
of pi.  If strict ISO and/or POSIX compliance are requested this
constant is not defined, but you can easily define it yourself:

     #define M_PI 3.14159265358979323846264338327

You can also compute the value of pi with the expression 'acos (-1.0)'.

 -- Function: double sin (double X)
 -- Function: float sinf (float X)
 -- Function: long double sinl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the sine of X, where X is given in radians.
     The return value is in the range '-1' to '1'.

 -- Function: double cos (double X)
 -- Function: float cosf (float X)
 -- Function: long double cosl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the cosine of X, where X is given in
     radians.  The return value is in the range '-1' to '1'.

 -- Function: double tan (double X)
 -- Function: float tanf (float X)
 -- Function: long double tanl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the tangent of X, where X is given in
     radians.

     Mathematically, the tangent function has singularities at odd
     multiples of pi/2.  If the argument X is too close to one of these
     singularities, 'tan' will signal overflow.

   In many applications where 'sin' and 'cos' are used, the sine and
cosine of the same angle are needed at the same time.  It is more
efficient to compute them simultaneously, so the library provides a
function to do that.

 -- Function: void sincos (double X, double *SINX, double *COSX)
 -- Function: void sincosf (float X, float *SINX, float *COSX)
 -- Function: void sincosl (long double X, long double *SINX, long
          double *COSX)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the sine of X in '*SINX' and the cosine of X
     in '*COS', where X is given in radians.  Both values, '*SINX' and
     '*COSX', are in the range of '-1' to '1'.

     This function is a GNU extension.  Portable programs should be
     prepared to cope with its absence.

   ISO C99 defines variants of the trig functions which work on complex
numbers.  The GNU C Library provides these functions, but they are only
useful if your compiler supports the new complex types defined by the
standard.  (As of this writing GCC supports complex numbers, but there
are bugs in the implementation.)

 -- Function: complex double csin (complex double Z)
 -- Function: complex float csinf (complex float Z)
 -- Function: complex long double csinl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the complex sine of Z.  The mathematical
     definition of the complex sine is

     sin (z) = 1/(2*i) * (exp (z*i) - exp (-z*i)).

 -- Function: complex double ccos (complex double Z)
 -- Function: complex float ccosf (complex float Z)
 -- Function: complex long double ccosl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the complex cosine of Z.  The mathematical
     definition of the complex cosine is

     cos (z) = 1/2 * (exp (z*i) + exp (-z*i))

 -- Function: complex double ctan (complex double Z)
 -- Function: complex float ctanf (complex float Z)
 -- Function: complex long double ctanl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the complex tangent of Z.  The mathematical
     definition of the complex tangent is

     tan (z) = -i * (exp (z*i) - exp (-z*i)) / (exp (z*i) + exp (-z*i))

     The complex tangent has poles at pi/2 + 2n, where n is an integer.
     'ctan' may signal overflow if Z is too close to a pole.


File: libc.info,  Node: Inverse Trig Functions,  Next: Exponents and Logarithms,  Prev: Trig Functions,  Up: Mathematics

19.3 Inverse Trigonometric Functions
====================================

These are the usual arc sine, arc cosine and arc tangent functions,
which are the inverses of the sine, cosine and tangent functions
respectively.

 -- Function: double asin (double X)
 -- Function: float asinf (float X)
 -- Function: long double asinl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions compute the arc sine of X--that is, the value whose
     sine is X.  The value is in units of radians.  Mathematically,
     there are infinitely many such values; the one actually returned is
     the one between '-pi/2' and 'pi/2' (inclusive).

     The arc sine function is defined mathematically only over the
     domain '-1' to '1'.  If X is outside the domain, 'asin' signals a
     domain error.

 -- Function: double acos (double X)
 -- Function: float acosf (float X)
 -- Function: long double acosl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions compute the arc cosine of X--that is, the value
     whose cosine is X.  The value is in units of radians.
     Mathematically, there are infinitely many such values; the one
     actually returned is the one between '0' and 'pi' (inclusive).

     The arc cosine function is defined mathematically only over the
     domain '-1' to '1'.  If X is outside the domain, 'acos' signals a
     domain error.

 -- Function: double atan (double X)
 -- Function: float atanf (float X)
 -- Function: long double atanl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions compute the arc tangent of X--that is, the value
     whose tangent is X.  The value is in units of radians.
     Mathematically, there are infinitely many such values; the one
     actually returned is the one between '-pi/2' and 'pi/2'
     (inclusive).

 -- Function: double atan2 (double Y, double X)
 -- Function: float atan2f (float Y, float X)
 -- Function: long double atan2l (long double Y, long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     This function computes the arc tangent of Y/X, but the signs of
     both arguments are used to determine the quadrant of the result,
     and X is permitted to be zero.  The return value is given in
     radians and is in the range '-pi' to 'pi', inclusive.

     If X and Y are coordinates of a point in the plane, 'atan2' returns
     the signed angle between the line from the origin to that point and
     the x-axis.  Thus, 'atan2' is useful for converting Cartesian
     coordinates to polar coordinates.  (To compute the radial
     coordinate, use 'hypot'; see *note Exponents and Logarithms::.)

     If both X and Y are zero, 'atan2' returns zero.

   ISO C99 defines complex versions of the inverse trig functions.

 -- Function: complex double casin (complex double Z)
 -- Function: complex float casinf (complex float Z)
 -- Function: complex long double casinl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions compute the complex arc sine of Z--that is, the
     value whose sine is Z.  The value returned is in radians.

     Unlike the real-valued functions, 'casin' is defined for all values
     of Z.

 -- Function: complex double cacos (complex double Z)
 -- Function: complex float cacosf (complex float Z)
 -- Function: complex long double cacosl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions compute the complex arc cosine of Z--that is, the
     value whose cosine is Z.  The value returned is in radians.

     Unlike the real-valued functions, 'cacos' is defined for all values
     of Z.

 -- Function: complex double catan (complex double Z)
 -- Function: complex float catanf (complex float Z)
 -- Function: complex long double catanl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions compute the complex arc tangent of Z--that is, the
     value whose tangent is Z.  The value is in units of radians.


File: libc.info,  Node: Exponents and Logarithms,  Next: Hyperbolic Functions,  Prev: Inverse Trig Functions,  Up: Mathematics

19.4 Exponentiation and Logarithms
==================================

 -- Function: double exp (double X)
 -- Function: float expf (float X)
 -- Function: long double expl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions compute 'e' (the base of natural logarithms) raised
     to the power X.

     If the magnitude of the result is too large to be representable,
     'exp' signals overflow.

 -- Function: double exp2 (double X)
 -- Function: float exp2f (float X)
 -- Function: long double exp2l (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions compute '2' raised to the power X.  Mathematically,
     'exp2 (x)' is the same as 'exp (x * log (2))'.

 -- Function: double exp10 (double X)
 -- Function: float exp10f (float X)
 -- Function: long double exp10l (long double X)
 -- Function: double pow10 (double X)
 -- Function: float pow10f (float X)
 -- Function: long double pow10l (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions compute '10' raised to the power X.
     Mathematically, 'exp10 (x)' is the same as 'exp (x * log (10))'.

     These functions are GNU extensions.  The name 'exp10' is preferred,
     since it is analogous to 'exp' and 'exp2'.

 -- Function: double log (double X)
 -- Function: float logf (float X)
 -- Function: long double logl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions compute the natural logarithm of X.  'exp (log
     (X))' equals X, exactly in mathematics and approximately in C.

     If X is negative, 'log' signals a domain error.  If X is zero, it
     returns negative infinity; if X is too close to zero, it may signal
     overflow.

 -- Function: double log10 (double X)
 -- Function: float log10f (float X)
 -- Function: long double log10l (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the base-10 logarithm of X.  'log10 (X)'
     equals 'log (X) / log (10)'.

 -- Function: double log2 (double X)
 -- Function: float log2f (float X)
 -- Function: long double log2l (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the base-2 logarithm of X.  'log2 (X)'
     equals 'log (X) / log (2)'.

 -- Function: double logb (double X)
 -- Function: float logbf (float X)
 -- Function: long double logbl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions extract the exponent of X and return it as a
     floating-point value.  If 'FLT_RADIX' is two, 'logb' is equal to
     'floor (log2 (x))', except it's probably faster.

     If X is de-normalized, 'logb' returns the exponent X would have if
     it were normalized.  If X is infinity (positive or negative),
     'logb' returns oo.  If X is zero, 'logb' returns oo.  It does not
     signal.

 -- Function: int ilogb (double X)
 -- Function: int ilogbf (float X)
 -- Function: int ilogbl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions are equivalent to the corresponding 'logb'
     functions except that they return signed integer values.

Since integers cannot represent infinity and NaN, 'ilogb' instead
returns an integer that can't be the exponent of a normal floating-point
number.  'math.h' defines constants so you can check for this.

 -- Macro: int FP_ILOGB0
     'ilogb' returns this value if its argument is '0'.  The numeric
     value is either 'INT_MIN' or '-INT_MAX'.

     This macro is defined in ISO C99.

 -- Macro: int FP_ILOGBNAN
     'ilogb' returns this value if its argument is 'NaN'.  The numeric
     value is either 'INT_MIN' or 'INT_MAX'.

     This macro is defined in ISO C99.

   These values are system specific.  They might even be the same.  The
proper way to test the result of 'ilogb' is as follows:

     i = ilogb (f);
     if (i == FP_ILOGB0 || i == FP_ILOGBNAN)
       {
         if (isnan (f))
           {
             /* Handle NaN.  */
           }
         else if (f  == 0.0)
           {
             /* Handle 0.0.  */
           }
         else
           {
             /* Some other value with large exponent,
                perhaps +Inf.  */
           }
       }

 -- Function: double pow (double BASE, double POWER)
 -- Function: float powf (float BASE, float POWER)
 -- Function: long double powl (long double BASE, long double POWER)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These are general exponentiation functions, returning BASE raised
     to POWER.

     Mathematically, 'pow' would return a complex number when BASE is
     negative and POWER is not an integral value.  'pow' can't do that,
     so instead it signals a domain error.  'pow' may also underflow or
     overflow the destination type.

 -- Function: double sqrt (double X)
 -- Function: float sqrtf (float X)
 -- Function: long double sqrtl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the nonnegative square root of X.

     If X is negative, 'sqrt' signals a domain error.  Mathematically,
     it should return a complex number.

 -- Function: double cbrt (double X)
 -- Function: float cbrtf (float X)
 -- Function: long double cbrtl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the cube root of X.  They cannot fail; every
     representable real value has a representable real cube root.

 -- Function: double hypot (double X, double Y)
 -- Function: float hypotf (float X, float Y)
 -- Function: long double hypotl (long double X, long double Y)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return 'sqrt (X*X + Y*Y)'.  This is the length of
     the hypotenuse of a right triangle with sides of length X and Y, or
     the distance of the point (X, Y) from the origin.  Using this
     function instead of the direct formula is wise, since the error is
     much smaller.  See also the function 'cabs' in *note Absolute
     Value::.

 -- Function: double expm1 (double X)
 -- Function: float expm1f (float X)
 -- Function: long double expm1l (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return a value equivalent to 'exp (X) - 1'.  They
     are computed in a way that is accurate even if X is near zero--a
     case where 'exp (X) - 1' would be inaccurate owing to subtraction
     of two numbers that are nearly equal.

 -- Function: double log1p (double X)
 -- Function: float log1pf (float X)
 -- Function: long double log1pl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions returns a value equivalent to 'log (1 + X)'.  They
     are computed in a way that is accurate even if X is near zero.

   ISO C99 defines complex variants of some of the exponentiation and
logarithm functions.

 -- Function: complex double cexp (complex double Z)
 -- Function: complex float cexpf (complex float Z)
 -- Function: complex long double cexpl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return 'e' (the base of natural logarithms) raised
     to the power of Z.  Mathematically, this corresponds to the value

     exp (z) = exp (creal (z)) * (cos (cimag (z)) + I * sin (cimag (z)))

 -- Function: complex double clog (complex double Z)
 -- Function: complex float clogf (complex float Z)
 -- Function: complex long double clogl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the natural logarithm of Z.  Mathematically,
     this corresponds to the value

     log (z) = log (cabs (z)) + I * carg (z)

     'clog' has a pole at 0, and will signal overflow if Z equals or is
     very close to 0.  It is well-defined for all other values of Z.

 -- Function: complex double clog10 (complex double Z)
 -- Function: complex float clog10f (complex float Z)
 -- Function: complex long double clog10l (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the base 10 logarithm of the complex value
     Z.  Mathematically, this corresponds to the value

     log (z) = log10 (cabs (z)) + I * carg (z)

     These functions are GNU extensions.

 -- Function: complex double csqrt (complex double Z)
 -- Function: complex float csqrtf (complex float Z)
 -- Function: complex long double csqrtl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the complex square root of the argument Z.
     Unlike the real-valued functions, they are defined for all values
     of Z.

 -- Function: complex double cpow (complex double BASE, complex double
          POWER)
 -- Function: complex float cpowf (complex float BASE, complex float
          POWER)
 -- Function: complex long double cpowl (complex long double BASE,
          complex long double POWER)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return BASE raised to the power of POWER.  This is
     equivalent to 'cexp (y * clog (x))'


File: libc.info,  Node: Hyperbolic Functions,  Next: Special Functions,  Prev: Exponents and Logarithms,  Up: Mathematics

19.5 Hyperbolic Functions
=========================

The functions in this section are related to the exponential functions;
see *note Exponents and Logarithms::.

 -- Function: double sinh (double X)
 -- Function: float sinhf (float X)
 -- Function: long double sinhl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the hyperbolic sine of X, defined
     mathematically as '(exp (X) - exp (-X)) / 2'.  They may signal
     overflow if X is too large.

 -- Function: double cosh (double X)
 -- Function: float coshf (float X)
 -- Function: long double coshl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These function return the hyperbolic cosine of X, defined
     mathematically as '(exp (X) + exp (-X)) / 2'.  They may signal
     overflow if X is too large.

 -- Function: double tanh (double X)
 -- Function: float tanhf (float X)
 -- Function: long double tanhl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the hyperbolic tangent of X, defined
     mathematically as 'sinh (X) / cosh (X)'.  They may signal overflow
     if X is too large.

   There are counterparts for the hyperbolic functions which take
complex arguments.

 -- Function: complex double csinh (complex double Z)
 -- Function: complex float csinhf (complex float Z)
 -- Function: complex long double csinhl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the complex hyperbolic sine of Z, defined
     mathematically as '(exp (Z) - exp (-Z)) / 2'.

 -- Function: complex double ccosh (complex double Z)
 -- Function: complex float ccoshf (complex float Z)
 -- Function: complex long double ccoshl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the complex hyperbolic cosine of Z, defined
     mathematically as '(exp (Z) + exp (-Z)) / 2'.

 -- Function: complex double ctanh (complex double Z)
 -- Function: complex float ctanhf (complex float Z)
 -- Function: complex long double ctanhl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the complex hyperbolic tangent of Z, defined
     mathematically as 'csinh (Z) / ccosh (Z)'.

 -- Function: double asinh (double X)
 -- Function: float asinhf (float X)
 -- Function: long double asinhl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the inverse hyperbolic sine of X--the value
     whose hyperbolic sine is X.

 -- Function: double acosh (double X)
 -- Function: float acoshf (float X)
 -- Function: long double acoshl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the inverse hyperbolic cosine of X--the
     value whose hyperbolic cosine is X.  If X is less than '1', 'acosh'
     signals a domain error.

 -- Function: double atanh (double X)
 -- Function: float atanhf (float X)
 -- Function: long double atanhl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the inverse hyperbolic tangent of X--the
     value whose hyperbolic tangent is X.  If the absolute value of X is
     greater than '1', 'atanh' signals a domain error; if it is equal to
     1, 'atanh' returns infinity.

 -- Function: complex double casinh (complex double Z)
 -- Function: complex float casinhf (complex float Z)
 -- Function: complex long double casinhl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the inverse complex hyperbolic sine of
     Z--the value whose complex hyperbolic sine is Z.

 -- Function: complex double cacosh (complex double Z)
 -- Function: complex float cacoshf (complex float Z)
 -- Function: complex long double cacoshl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the inverse complex hyperbolic cosine of
     Z--the value whose complex hyperbolic cosine is Z.  Unlike the
     real-valued functions, there are no restrictions on the value of Z.

 -- Function: complex double catanh (complex double Z)
 -- Function: complex float catanhf (complex float Z)
 -- Function: complex long double catanhl (complex long double Z)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     These functions return the inverse complex hyperbolic tangent of
     Z--the value whose complex hyperbolic tangent is Z.  Unlike the
     real-valued functions, there are no restrictions on the value of Z.


File: libc.info,  Node: Special Functions,  Next: Errors in Math Functions,  Prev: Hyperbolic Functions,  Up: Mathematics

19.6 Special Functions
======================

These are some more exotic mathematical functions which are sometimes
useful.  Currently they only have real-valued versions.

 -- Function: double erf (double X)
 -- Function: float erff (float X)
 -- Function: long double erfl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     'erf' returns the error function of X.  The error function is
     defined as
          erf (x) = 2/sqrt(pi) * integral from 0 to x of exp(-t^2) dt

 -- Function: double erfc (double X)
 -- Function: float erfcf (float X)
 -- Function: long double erfcl (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     'erfc' returns '1.0 - erf(X)', but computed in a fashion that
     avoids round-off error when X is large.

 -- Function: double lgamma (double X)
 -- Function: float lgammaf (float X)
 -- Function: long double lgammal (long double X)
     Preliminary: | MT-Unsafe race:signgam | AS-Unsafe | AC-Safe | *Note
     POSIX Safety Concepts::.

     'lgamma' returns the natural logarithm of the absolute value of the
     gamma function of X.  The gamma function is defined as
          gamma (x) = integral from 0 to oo of t^(x-1) e^-t dt

     The sign of the gamma function is stored in the global variable
     SIGNGAM, which is declared in 'math.h'.  It is '1' if the
     intermediate result was positive or zero, or '-1' if it was
     negative.

     To compute the real gamma function you can use the 'tgamma'
     function or you can compute the values as follows:
          lgam = lgamma(x);
          gam  = signgam*exp(lgam);

     The gamma function has singularities at the non-positive integers.
     'lgamma' will raise the zero divide exception if evaluated at a
     singularity.

 -- Function: double lgamma_r (double X, int *SIGNP)
 -- Function: float lgammaf_r (float X, int *SIGNP)
 -- Function: long double lgammal_r (long double X, int *SIGNP)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     'lgamma_r' is just like 'lgamma', but it stores the sign of the
     intermediate result in the variable pointed to by SIGNP instead of
     in the SIGNGAM global.  This means it is reentrant.

 -- Function: double gamma (double X)
 -- Function: float gammaf (float X)
 -- Function: long double gammal (long double X)
     Preliminary: | MT-Unsafe race:signgam | AS-Unsafe | AC-Safe | *Note
     POSIX Safety Concepts::.

     These functions exist for compatibility reasons.  They are
     equivalent to 'lgamma' etc.  It is better to use 'lgamma' since for
     one the name reflects better the actual computation, moreover
     'lgamma' is standardized in ISO C99 while 'gamma' is not.

 -- Function: double tgamma (double X)
 -- Function: float tgammaf (float X)
 -- Function: long double tgammal (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     'tgamma' applies the gamma function to X.  The gamma function is
     defined as
          gamma (x) = integral from 0 to oo of t^(x-1) e^-t dt

     This function was introduced in ISO C99.

 -- Function: double j0 (double X)
 -- Function: float j0f (float X)
 -- Function: long double j0l (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     'j0' returns the Bessel function of the first kind of order 0 of X.
     It may signal underflow if X is too large.

 -- Function: double j1 (double X)
 -- Function: float j1f (float X)
 -- Function: long double j1l (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     'j1' returns the Bessel function of the first kind of order 1 of X.
     It may signal underflow if X is too large.

 -- Function: double jn (int N, double X)
 -- Function: float jnf (int N, float X)
 -- Function: long double jnl (int N, long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     'jn' returns the Bessel function of the first kind of order N of X.
     It may signal underflow if X is too large.

 -- Function: double y0 (double X)
 -- Function: float y0f (float X)
 -- Function: long double y0l (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     'y0' returns the Bessel function of the second kind of order 0 of
     X.  It may signal underflow if X is too large.  If X is negative,
     'y0' signals a domain error; if it is zero, 'y0' signals overflow
     and returns -oo.

 -- Function: double y1 (double X)
 -- Function: float y1f (float X)
 -- Function: long double y1l (long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     'y1' returns the Bessel function of the second kind of order 1 of
     X.  It may signal underflow if X is too large.  If X is negative,
     'y1' signals a domain error; if it is zero, 'y1' signals overflow
     and returns -oo.

 -- Function: double yn (int N, double X)
 -- Function: float ynf (int N, float X)
 -- Function: long double ynl (int N, long double X)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     'yn' returns the Bessel function of the second kind of order N of
     X.  It may signal underflow if X is too large.  If X is negative,
     'yn' signals a domain error; if it is zero, 'yn' signals overflow
     and returns -oo.


File: libc.info,  Node: Errors in Math Functions,  Next: Pseudo-Random Numbers,  Prev: Special Functions,  Up: Mathematics

19.7 Known Maximum Errors in Math Functions
===========================================

This section lists the known errors of the functions in the math
library.  Errors are measured in "units of the last place".  This is a
measure for the relative error.  For a number z with the representation
d.d...d*2^e (we assume IEEE floating-point numbers with base 2) the ULP
is represented by

     |d.d...d - (z / 2^e)| / 2^(p - 1)

where p is the number of bits in the mantissa of the floating-point
number representation.  Ideally the error for all functions is always
less than 0.5ulps in round-to-nearest mode.  Using rounding bits this is
also possible and normally implemented for the basic operations.  Except
for certain functions such as 'sqrt', 'fma' and 'rint' whose results are
fully specified by reference to corresponding IEEE 754 floating-point
operations, and conversions between strings and floating point, the GNU
C Library does not aim for correctly rounded results for functions in
the math library, and does not aim for correctness in whether "inexact"
exceptions are raised.  Instead, the goals for accuracy of functions
without fully specified results are as follows; some functions have bugs
meaning they do not meet these goals in all cases.  In future, the GNU C
Library may provide some other correctly rounding functions under the
names such as 'crsin' proposed for an extension to ISO C.

   * Each function with a floating-point result behaves as if it
     computes an infinite-precision result that is within a few ulp (in
     both real and complex parts, for functions with complex results) of
     the mathematically correct value of the function (interpreted
     together with ISO C or POSIX semantics for the function in
     question) at the exact value passed as the input.  Exceptions are
     raised appropriately for this value and in accordance with IEEE 754
     / ISO C / POSIX semantics, and it is then rounded according to the
     current rounding direction to the result that is returned to the
     user.  'errno' may also be set (*note Math Error Reporting::).

   * For the IBM 'long double' format, as used on PowerPC GNU/Linux, the
     accuracy goal is weaker for input values not exactly representable
     in 106 bits of precision; it is as if the input value is some value
     within 0.5ulp of the value actually passed, where "ulp" is
     interpreted in terms of a fixed-precision 106-bit mantissa, but not
     necessarily the exact value actually passed with discontiguous
     mantissa bits.

   * Functions behave as if the infinite-precision result computed is
     zero, infinity or NaN if and only if that is the mathematically
     correct infinite-precision result.  They behave as if the
     infinite-precision result computed always has the same sign as the
     mathematically correct result.

   * If the mathematical result is more than a few ulp above the
     overflow threshold for the current rounding direction, the value
     returned is the appropriate overflow value for the current rounding
     direction, with the overflow exception raised.

   * If the mathematical result has magnitude well below half the least
     subnormal magnitude, the returned value is either zero or the least
     subnormal (in each case, with the correct sign), according to the
     current rounding direction and with the underflow exception raised.

   * Where the mathematical result underflows and is not exactly
     representable as a floating-point value, the underflow exception is
     raised (so there may be spurious underflow exceptions in cases
     where the underflowing result is exact, but not missing underflow
     exceptions in cases where it is inexact).

   * The GNU C Library does not aim for functions to satisfy other
     properties of the underlying mathematical function, such as
     monotonicity, where not implied by the above goals.

   * All the above applies to both real and complex parts, for complex
     functions.

   Therefore many of the functions in the math library have errors.  The
table lists the maximum error for each function which is exposed by one
of the existing tests in the test suite.  The table tries to cover as
much as possible and list the actual maximum error (or at least a
ballpark figure) but this is often not achieved due to the large search
space.

   The table lists the ULP values for different architectures.
Different architectures have different results since their hardware
support for floating-point operations varies and also the existing
hardware support is different.

Function      aarch64         Alpha           ARM             hppa/fpu        IA64
acosf         -               -               -               -               -
acos          -               -               -               -               -
acosl         -               -               -               -               -
acoshf        -               -               -               -               -
acosh         1               1               1               1               -
acoshl        1               1               -               -               -
asinf         -               -               -               -               -
asin          -               -               -               -               -
asinl         1               1               -               -               -
asinhf        1               1               1               1               -
asinh         1               1               1               1               -
asinhl        1               1               -               -               -
atanf         -               -               -               -               -
atan          1               -               -               -               -
atanl         -               -               -               -               -
atanhf        1               1               1               1               -
atanh         -               -               -               -               -
atanhl        1               1               -               -               -
atan2f        1               1               1               1               -
atan2         -               -               -               -               -
atan2l        1               1               -               -               -
cabsf         -               -               -               -               -
cabs          -               -               -               -               -
cabsl         -               -               -               -               -
cacosf        2 + i 2         2 + i 2         2 + i 2         2 + i 2         2 + i 2
cacos         1 + i 1         1 + i 1         1 + i 1         1 + i 1         1 + i 1
cacosl        2 + i 2         2 + i 2         -               -               1 + i 2
cacoshf       2 + i 2         2 + i 2         2 + i 2         2 + i 2         2 + i 2
cacosh        1 + i 1         1 + i 1         1 + i 1         1 + i 1         1 + i 1
cacoshl       2 + i 2         2 + i 2         -               -               2 + i 1
cargf         -               -               -               -               -
carg          -               -               -               -               -
cargl         -               -               -               -               -
casinf        1 + i 2         1 + i 2         1 + i 2         1 + i 2         1 + i 2
casin         1 + i 1         1 + i 1         1 + i 1         1 + i 1         1 + i 1
casinl        2 + i 2         2 + i 2         -               1 + i 0         1 + i 2
casinhf       2 + i 1         2 + i 1         2 + i 1         2 + i 1         2 + i 1
casinh        1 + i 1         1 + i 1         1 + i 1         5 + i 3         1 + i 1
casinhl       2 + i 2         2 + i 2         -               5 + i 3         2 + i 1
catanf        1 + i 1         1 + i 1         1 + i 1         1 + i 1         0 + i 1
catan         0 + i 1         0 + i 1         0 + i 1         0 + i 1         0 + i 1
catanl        1 + i 1         1 + i 1         -               0 + i 1         0 + i 1
catanhf       1 + i 1         1 + i 1         1 + i 1         1 + i 1         1 + i 0
catanh        1 + i 0         1 + i 0         1 + i 0         4 + i 0         1 + i 0
catanhl       1 + i 1         1 + i 1         -               4 + i 0         1 + i 0
cbrtf         1               1               1               1               -
cbrt          1               1               1               1               -
cbrtl         1               1               -               1               -
ccosf         1 + i 1         1 + i 1         1 + i 1         1 + i 1         0 + i 1
ccos          1 + i 1         1 + i 1         1 + i 1         1 + i 1         1 + i 1
ccosl         1 + i 1         1 + i 1         -               1 + i 0         1 + i 1
ccoshf        1 + i 1         1 + i 1         1 + i 1         1 + i 1         1 + i 1
ccosh         1 + i 1         1 + i 1         1 + i 1         1 + i 1         1 + i 1
ccoshl        1 + i 1         1 + i 1         -               1 + i 0         0 + i 1
ceilf         -               -               -               -               -
ceil          -               -               -               -               -
ceill         -               -               -               -               -
cexpf         1 + i 2         1 + i 2         1 + i 2         1 + i 2         1 + i 2
cexp          2 + i 1         2 + i 1         2 + i 1         2 + i 1         2 + i 1
cexpl         1 + i 1         1 + i 1         -               -               1 + i 1
cimagf        -               -               -               -               -
cimag         -               -               -               -               -
cimagl        -               -               -               -               -
clogf         1 + i 1         1 + i 1         1 + i 1         1 + i 1         1 + i 0
clog          1 + i 1         1 + i 0         1 + i 0         1 + i 0         1 + i 1
clogl         1 + i 1         1 + i 1         -               -               1 + i 1
clog10f       2 + i 1         2 + i 1         2 + i 1         2 + i 1         2 + i 1
clog10        2 + i 1         2 + i 1         2 + i 1         2 + i 1         2 + i 1
clog10l       1 + i 2         1 + i 2         -               0 + i 1         1 + i 1
conjf         -               -               -               -               -
conj          -               -               -               -               -
conjl         -               -               -               -               -
copysignf     -               -               -               -               -
copysign      -               -               -               -               -
copysignl     -               -               -               -               -
cosf          1               1               1               1               -
cos           -               -               -               2               1
cosl          1               1               -               2               -
coshf         1               1               1               1               -
cosh          1               1               1               1               -
coshl         1               1               -               -               -
cpowf         5 + i 2         4 + i 2         4 + i 2         4 + i 2         5 + i 2
cpow          2 + i 0         2 + i 0         2 + i 0         2 + i 2         2 + i 0
cpowl         4 + i 1         4 + i 1         -               2 + i 2         3 + i 4
cprojf        -               -               -               -               -
cproj         -               -               -               -               -
cprojl        -               -               -               -               -
crealf        -               -               -               -               -
creal         -               -               -               -               -
creall        -               -               -               -               -
csinf         1 + i 0         1 + i 0         1 + i 0         1 + i 0         1 + i 1
csin          1 + i 0         1 + i 0         1 + i 0         1 + i 0         1 + i 0
csinl         1 + i 1         1 + i 1         -               -               1 + i 0
csinhf        1 + i 1         1 + i 1         1 + i 1         1 + i 1         1 + i 1
csinh         0 + i 1         0 + i 1         0 + i 1         0 + i 1         1 + i 1
csinhl        1 + i 1         1 + i 1         -               0 + i 1         1 + i 0
csqrtf        1 + i 1         1 + i 1         1 + i 1         1 + i 1         1 + i 1
csqrt         1 + i 1         1 + i 1         1 + i 1         1 + i 1         1 + i 1
csqrtl        1 + i 1         1 + i 1         -               -               1 + i 1
ctanf         1 + i 1         1 + i 1         1 + i 1         1 + i 1         1 + i 1
ctan          1 + i 2         1 + i 2         1 + i 2         1 + i 2         1 + i 2
ctanl         3 + i 3         3 + i 3         -               0 + i 1         2 + i 2
ctanhf        2 + i 1         1 + i 2         1 + i 2         1 + i 2         1 + i 1
ctanh         2 + i 2         2 + i 2         2 + i 2         2 + i 2         2 + i 2
ctanhl        3 + i 3         3 + i 3         -               1 + i 0         1 + i 2
erff          -               -               -               -               -
erf           1               1               1               1               -
erfl          1               1               -               1               -
erfcf         1               1               1               1               -
erfc          1               1               1               1               -
erfcl         1               1               -               1               -
expf          -               -               -               -               -
exp           -               -               -               -               -
expl          -               -               -               -               -
exp10f        -               -               -               2               -
exp10         1               1               1               6               -
exp10l        1               1               -               6               -
exp2f         -               -               -               -               -
exp2          -               -               -               -               -
exp2l         1               1               -               -               -
expm1f        1               1               1               1               -
expm1         1               1               1               1               -
expm1l        1               1               -               1               1
fabsf         -               -               -               -               -
fabs          -               -               -               -               -
fabsl         -               -               -               -               -
fdimf         -               -               -               -               -
fdim          -               -               -               -               -
fdiml         -               -               -               -               -
floorf        -               -               -               -               -
floor         -               -               -               -               -
floorl        -               -               -               -               -
fmaf          -               -               -               -               -
fma           -               -               -               -               -
fmal          -               -               -               -               -
fmaxf         -               -               -               -               -
fmax          -               -               -               -               -
fmaxl         -               -               -               -               -
fminf         -               -               -               -               -
fmin          -               -               -               -               -
fminl         -               -               -               -               -
fmodf         -               -               -               -               -
fmod          -               -               -               -               -
fmodl         -               -               -               -               -
frexpf        -               -               -               -               -
frexp         -               -               -               -               -
frexpl        -               -               -               -               -
gammaf        1               1               1               2               -
gamma         1               1               1               1               -
gammal        1               1               -               -               -
hypotf        -               -               -               1               -
hypot         1               1               1               1               -
hypotl        1               1               -               -               -
ilogbf        -               -               -               -               -
ilogb         -               -               -               -               -
ilogbl        -               -               -               -               -
j0f           2               2               2               2               2
j0            2               2               2               2               2
j0l           2               2               -               2               2
j1f           2               2               2               2               2
j1            1               1               1               1               1
j1l           4               4               -               1               1
jnf           4               4               4               5               4
jn            4               4               4               4               4
jnl           7               7               -               4               4
lgammaf       1               1               1               2               -
lgamma        1               1               1               1               -
lgammal       1               1               -               1               -
lrintf        -               -               -               -               -
lrint         -               -               -               -               -
lrintl        -               -               -               -               -
llrintf       -               -               -               -               -
llrint        -               -               -               -               -
llrintl       -               -               -               -               -
logf          1               1               1               1               -
log           -               -               -               -               -
logl          1               1               -               -               -
log10f        2               2               2               2               -
log10         1               1               1               1               -
log10l        1               1               -               1               -
log1pf        1               1               1               1               -
log1p         -               -               -               -               -
log1pl        1               1               -               -               -
log2f         -               -               -               -               -
log2          -               -               -               -               -
log2l         1               1               -               -               -
logbf         -               -               -               -               -
logb          -               -               -               -               -
logbl         -               -               -               -               -
lroundf       -               -               -               -               -
lround        -               -               -               -               -
lroundl       -               -               -               -               -
llroundf      -               -               -               -               -
llround       -               -               -               -               -
llroundl      -               -               -               -               -
modff         -               -               -               -               -
modf          -               -               -               -               -
modfl         -               -               -               -               -
nearbyintf    -               -               -               -               -
nearbyint     -               -               -               -               -
nearbyintl    -               -               -               -               -
nextafterf    -               -               -               -               -
nextafter     -               -               -               -               -
nextafterl    -               -               -               -               -
nexttowardf   -               -               -               -               -
nexttoward    -               -               -               -               -
nexttowardl   -               -               -               -               -
powf          1               1               1               1               -
pow           -               -               -               -               -
powl          1               1               -               -               -
remainderf    -               -               -               -               -
remainder     -               -               -               -               -
remainderl    -               -               -               -               -
remquof       -               -               -               -               -
remquo        -               -               -               -               -
remquol       -               -               -               -               -
rintf         -               -               -               -               -
rint          -               -               -               -               -
rintl         -               -               -               -               -
roundf        -               -               -               -               -
round         -               -               -               -               -
roundl        -               -               -               -               -
scalbf        -               -               -               -               -
scalb         -               -               -               -               -
scalbl        -               -               -               -               -
scalbnf       -               -               -               -               -
scalbn        -               -               -               -               -
scalbnl       -               -               -               -               -
scalblnf      -               -               -               -               -
scalbln       -               -               -               -               -
scalblnl      -               -               -               -               -
sinf          1               1               1               1               -
sin           -               -               -               -               1
sinl          1               1               -               -               -
sincosf       1               1               1               1               -
sincos        -               -               -               1               1
sincosl       1               1               -               1               -
sinhf         -               -               -               -               -
sinh          -               -               -               -               -
sinhl         -               -               -               -               -
sqrtf         -               -               -               -               -
sqrt          -               -               -               -               -
sqrtl         -               -               -               -               -
tanf          -               -               -               -               -
tan           -               -               -               1               -
tanl          1               1               -               1               -
tanhf         -               -               -               -               -
tanh          -               -               -               -               -
tanhl         1               1               -               -               -
tgammaf       3               3               3               3               -
tgamma        4               4               4               4               -
tgammal       4               4               -               1               1
truncf        -               -               -               -               -
trunc         -               -               -               -               -
truncl        -               -               -               -               -
y0f           1               1               1               1               1
y0            2               2               2               2               2
y0l           3               3               -               2               1
y1f           2               2               2               2               2
y1            3               3               3               3               3
y1l           2               2               -               3               2
ynf           2               2               2               2               3
yn            3               3               3               3               3
ynl           4               4               -               3               2
Function      m68k/coldfire/fpum68k/m680x0/fpumicroblaze      mips/mips32     mips/mips64
acosf         -               -               -               -               -
acos          -               -               -               -               -
acosl         -               -               -               -               -
acoshf        -               -               -               -               -
acosh         -               1               1               1               1
acoshl        -               -               -               -               1
asinf         -               -               -               -               -
asin          -               -               -               -               -
asinl         -               -               -               -               1
asinhf        -               1               1               1               1
asinh         -               -               1               1               1
asinhl        -               1               -               -               1
atanf         -               -               -               -               -
atan          -               -               -               -               -
atanl         -               -               -               -               -
atanhf        1               -               1               1               1
atanh         -               -               -               -               -
atanhl        -               -               -               -               1
atan2f        1               -               1               1               1
atan2         -               -               -               -               -
atan2l        -               1               -               -               1
cabsf         -               -               -               -               -
cabs          -               -               -               -               -
cabsl         -               -               -               -               -
cacosf        -               2 + i 1         2 + i 2         2 + i 2         2 + i 2
cacos         -               1 + i 1         1 + i 1         1 + i 1         1 + i 1
cacosl        -               1 + i 2         -               -               2 + i 2
cacoshf       0 + i 1         1 + i 2         2 + i 2         2 + i 2         2 + i 2
cacosh        -               1 + i 1         1 + i 1         1 + i 1         1 + i 1
cacoshl       -               2 + i 1         -               -               2 + i 2
cargf         -               -               -               -               -
carg          -               -               -               -               -
cargl         -               -               -               -               -
casinf        1 + i 0         1 + i 1         1 + i 2         1 + i 2         1 + i 2
casin         1 + i 0         1 + i 1         1 + i 1         1 + i 1         1 + i 1
casinl        -               1 + i 2         -               -               2 + i 2
casinhf       1 + i 6         1 + i 1         2 + i 1         2 + i 1         2 + i 1
casinh        5 + i 3         1 + i 1         1 + i 1         1 + i 1         1 + i 1
casinhl       -               2 + i 1         -               -               2 + i 2
catanf        0 + i 1         0 + i 1         1 + i 1         1 + i 1         1 + i 1
catan         0 + i 1         0 + i 1         0 + i 1         0 + i 1         0 + i 1
catanl        -               1 + i 1         -               -               1 + i 1
catanhf       -               1 + i 0         1 + i 1         1 + i 1         1 + i 1
catanh        4 + i 0         1 + i 0         1 + i 0         1 + i 0         1 + i 0
catanhl       -               1 + i 1         -               -               1 + i 1
cbrtf         -               1               1               1               1
cbrt          1               1               1               1               1
cbrtl         -               1               -               -               1
ccosf         1 + i 1         -               1 + i 1         1 + i 1         1 + i 1
ccos          1 + i 0         -               1 + i 1         1 + i 1         1 + i 1
ccosl         -               1 + i 1         -               -               1 + i 1
ccoshf        1 + i 1         -               1 + i 1         1 + i 1         1 + i 1
ccosh         1 + i 0         -               1 + i 1         1 + i 1         1 + i 1
ccoshl        -               0 + i 1         -               -               1 + i 1
ceilf         -               -               -               -               -
ceil          -               -               -               -               -
ceill         -               -               -               -               -
cexpf         1 + i 1         -               1 + i 2         1 + i 2         1 + i 2
cexp          -               -               2 + i 1         2 + i 1         2 + i 1
cexpl         -               1 + i 1         -               -               1 + i 1
cimagf        -               -               -               -               -
cimag         -               -               -               -               -
cimagl        -               -               -               -               -
clogf         1 + i 0         1 + i 1         1 + i 1         1 + i 1         1 + i 1
clog          -               1 + i 1         1 + i 0         1 + i 0         1 + i 0
clogl         -               1 + i 1         -               -               1 + i 1
clog10f       1 + i 1         1 + i 1         2 + i 1         2 + i 1         2 + i 1
clog10        0 + i 1         1 + i 1         2 + i 1         2 + i 1         2 + i 1
clog10l       -               1 + i 2         -               -               1 + i 2
conjf         -               -               -               -               -
conj          -               -               -               -               -
conjl         -               -               -               -               -
copysignf     -               -               -               -               -
copysign      -               -               -               -               -
copysignl     -               -               -               -               -
cosf          1               -               1               1               1
cos           2               1               -               -               -
cosl          -               -               -               -               1
coshf         -               -               1               1               1
cosh          -               -               1               1               1
coshl         -               -               -               -               1
cpowf         4 + i 2         3 + i 5         4 + i 2         4 + i 2         4 + i 2
cpow          2 + i 2         1 + i 0         2 + i 0         2 + i 0         2 + i 0
cpowl         -               3 + i 1         -               -               4 + i 1
cprojf        -               -               -               -               -
cproj         -               -               -               -               -
cprojl        -               -               -               -               -
crealf        -               -               -               -               -
creal         -               -               -               -               -
creall        -               -               -               -               -
csinf         -               -               1 + i 0         1 + i 0         1 + i 0
csin          -               -               1 + i 0         1 + i 0         1 + i 0
csinl         -               1 + i 0         -               -               1 + i 1
csinhf        1 + i 1         -               1 + i 1         1 + i 1         1 + i 1
csinh         0 + i 1         -               0 + i 1         0 + i 1         0 + i 1
csinhl        -               1 + i 0         -               -               1 + i 1
csqrtf        1 + i 0         -               1 + i 1         1 + i 1         1 + i 1
csqrt         -               1 + i 1         1 + i 1         1 + i 1         1 + i 1
csqrtl        -               1 + i 1         -               -               1 + i 1
ctanf         -               1 + i 1         1 + i 1         1 + i 1         1 + i 1
ctan          0 + i 1         1 + i 1         1 + i 2         1 + i 2         1 + i 2
ctanl         -               2 + i 2         -               -               3 + i 3
ctanhf        2 + i 1         1 + i 2         1 + i 2         1 + i 2         1 + i 2
ctanh         1 + i 0         1 + i 1         2 + i 2         2 + i 2         2 + i 2
ctanhl        -               2 + i 2         -               -               3 + i 3
erff          -               -               -               -               -
erf           1               -               1               1               1
erfl          -               1               -               -               1
erfcf         -               1               1               1               1
erfc          1               -               1               1               1
erfcl         -               1               -               -               1
expf          -               -               -               -               -
exp           -               -               -               -               -
expl          -               -               -               -               -
exp10f        2               -               -               -               -
exp10         6               -               1               1               1
exp10l        -               -               -               -               1
exp2f         -               -               -               -               -
exp2          -               -               -               -               -
exp2l         -               -               -               -               1
expm1f        1               -               1               1               1
expm1         1               -               1               1               1
expm1l        -               1               -               -               1
fabsf         -               -               -               -               -
fabs          -               -               -               -               -
fabsl         -               -               -               -               -
fdimf         -               -               -               -               -
fdim          -               -               -               -               -
fdiml         -               -               -               -               -
floorf        -               -               -               -               -
floor         -               -               -               -               -
floorl        -               -               -               -               -
fmaf          -               -               -               -               -
fma           -               -               -               -               -
fmal          -               -               -               -               -
fmaxf         -               -               -               -               -
fmax          -               -               -               -               -
fmaxl         -               -               -               -               -
fminf         -               -               -               -               -
fmin          -               -               -               -               -
fminl         -               -               -               -               -
fmodf         -               -               -               -               -
fmod          -               -               -               -               -
fmodl         -               -               -               -               -
frexpf        -               -               -               -               -
frexp         -               -               -               -               -
frexpl        -               -               -               -               -
gammaf        -               -               1               1               1
gamma         -               -               1               1               1
gammal        -               1               -               -               1
hypotf        1               -               -               -               -
hypot         -               1               1               1               1
hypotl        -               1               -               -               1
ilogbf        -               -               -               -               -
ilogb         -               -               -               -               -
ilogbl        -               -               -               -               -
j0f           2               2               2               2               2
j0            2               1               2               2               2
j0l           -               2               -               -               2
j1f           2               2               2               2               2
j1            1               -               1               1               1
j1l           -               1               -               -               4
jnf           4               2               4               4               4
jn            4               1               4               4               4
jnl           -               4               -               -               7
lgammaf       2               -               1               1               1
lgamma        1               -               1               1               1
lgammal       -               1               -               -               1
lrintf        -               -               -               -               -
lrint         -               -               -               -               -
lrintl        -               -               -               -               -
llrintf       -               -               -               -               -
llrint        -               -               -               -               -
llrintl       -               -               -               -               -
logf          -               -               1               1               1
log           -               -               -               -               -
logl          -               -               -               -               1
log10f        2               -               2               2               2
log10         1               -               1               1               1
log10l        -               -               -               -               1
log1pf        1               -               1               1               1
log1p         -               -               -               -               -
log1pl        -               -               -               -               1
log2f         -               -               -               -               -
log2          -               -               -               -               -
log2l         -               -               -               -               1
logbf         -               -               -               -               -
logb          -               -               -               -               -
logbl         -               -               -               -               -
lroundf       -               -               -               -               -
lround        -               -               -               -               -
lroundl       -               -               -               -               -
llroundf      -               -               -               -               -
llround       -               -               -               -               -
llroundl      -               -               -               -               -
modff         -               -               -               -               -
modf          -               -               -               -               -
modfl         -               -               -               -               -
nearbyintf    -               -               -               -               -
nearbyint     -               -               -               -               -
nearbyintl    -               -               -               -               -
nextafterf    -               -               -               -               -
nextafter     -               -               -               -               -
nextafterl    -               -               -               -               -
nexttowardf   -               -               -               -               -
nexttoward    -               -               -               -               -
nexttowardl   -               -               -               -               -
powf          -               5               1               1               1
pow           -               1               -               -               -
powl          -               7               -               -               1
remainderf    -               -               -               -               -
remainder     -               -               -               -               -
remainderl    -               -               -               -               -
remquof       -               -               -               -               -
remquo        -               -               -               -               -
remquol       -               -               -               -               -
rintf         -               -               -               -               -
rint          -               -               -               -               -
rintl         -               -               -               -               -
roundf        -               -               -               -               -
round         -               -               -               -               -
roundl        -               -               -               -               -
scalbf        -               -               -               -               -
scalb         -               -               -               -               -
scalbl        -               -               -               -               -
scalbnf       -               -               -               -               -
scalbn        -               -               -               -               -
scalbnl       -               -               -               -               -
scalblnf      -               -               -               -               -
scalbln       -               -               -               -               -
scalblnl      -               -               -               -               -
sinf          -               -               1               1               1
sin           -               1               -               -               -
sinl          -               -               -               -               1
sincosf       1               -               1               1               1
sincos        1               -               -               -               -
sincosl       -               -               -               -               1
sinhf         -               -               -               -               -
sinh          -               -               -               -               -
sinhl         -               -               -               -               -
sqrtf         -               -               -               -               -
sqrt          -               -               -               -               -
sqrtl         -               -               -               -               -
tanf          -               -               -               -               -
tan           1               -               -               -               -
tanl          -               -               -               -               1
tanhf         -               -               -               -               -
tanh          -               -               -               -               -
tanhl         -               -               -               -               1
tgammaf       1               3               3               3               3
tgamma        1               4               4               4               4
tgammal       -               9               -               -               4
truncf        -               -               -               -               -
trunc         -               -               -               -               -
truncl        -               -               -               -               -
y0f           1               1               1               1               1
y0            2               1               2               2               2
y0l           -               1               -               -               3
y1f           2               2               2               2               2
y1            3               1               3               3               3
y1l           -               2               -               -               2
ynf           2               3               2               2               2
yn            3               1               3               3               3
ynl           -               4               -               -               4
Function      tile            Generic         ix86            PowerPC         powerpc/nofpu
acosf         -               -               -               -               -
acos          -               -               -               -               -
acosl         -               -               1               1               1
acoshf        -               -               -               -               -
acosh         1               -               -               1               1
acoshl        -               -               -               1               1
asinf         -               -               -               -               -
asin          -               -               -               -               -
asinl         -               -               -               2               2
asinhf        1               -               -               1               1
asinh         1               -               -               1               1
asinhl        -               -               1               1               1
atanf         -               -               -               -               -
atan          -               -               -               1               -
atanl         -               -               -               -               -
atanhf        1               -               -               1               1
atanh         -               -               -               -               -
atanhl        -               -               1               1               1
atan2f        1               -               -               1               1
atan2         -               -               -               -               -
atan2l        -               -               1               2               2
cabsf         -               -               -               1               -
cabs          -               -               -               -               -
cabsl         -               -               -               1               1
cacosf        2 + i 2         -               1 + i 1         2 + i 2         2 + i 2
cacos         1 + i 1         -               1 + i 1         1 + i 3         1 + i 1
cacosl        -               -               1 + i 2         1 + i 2         2 + i 2
cacoshf       2 + i 2         -               1 + i 1         7 + i 3         2 + i 2
cacosh        1 + i 1         -               1 + i 1         1 + i 1         1 + i 1
cacoshl       -               -               2 + i 1         2 + i 1         2 + i 2
cargf         -               -               -               -               -
carg          -               -               -               -               -
cargl         -               -               -               1               1
casinf        1 + i 2         -               1 + i 1         1 + i 2         1 + i 2
casin         1 + i 1         -               1 + i 1         1 + i 3         1 + i 1
casinl        -               -               1 + i 2         1 + i 2         2 + i 2
casinhf       2 + i 1         -               1 + i 1         2 + i 1         2 + i 1
casinh        1 + i 1         -               1 + i 1         5 + i 3         1 + i 1
casinhl       -               -               2 + i 1         2 + i 1         2 + i 2
catanf        1 + i 1         -               0 + i 1         4 + i 1         1 + i 1
catan         0 + i 1         -               0 + i 1         0 + i 1         0 + i 1
catanl        -               -               0 + i 1         1 + i 1         1 + i 1
catanhf       1 + i 1         -               1 + i 0         1 + i 1         1 + i 1
catanh        1 + i 0         -               1 + i 0         4 + i 0         1 + i 0
catanhl       -               -               1 + i 0         1 + i 1         1 + i 1
cbrtf         1               -               -               1               1
cbrt          1               -               1               1               1
cbrtl         -               -               1               1               1
ccosf         1 + i 1         -               1 + i 1         1 + i 1         1 + i 1
ccos          1 + i 1         -               1 + i 1         1 + i 1         1 + i 1
ccosl         -               -               1 + i 1         1 + i 1         1 + i 2
ccoshf        1 + i 1         -               1 + i 1         1 + i 1         1 + i 1
ccosh         1 + i 1         -               1 + i 1         1 + i 1         1 + i 1
ccoshl        -               -               0 + i 1         1 + i 2         1 + i 2
ceilf         -               -               -               -               -
ceil          -               -               -               -               -
ceill         -               -               -               -               -
cexpf         1 + i 2         -               1 + i 1         1 + i 2         1 + i 2
cexp          2 + i 1         -               1 + i 1         2 + i 1         2 + i 1
cexpl         -               -               1 + i 1         2 + i 2         2 + i 2
cimagf        -               -               -               -               -
cimag         -               -               -               -               -
cimagl        -               -               -               -               -
clogf         1 + i 1         -               1 + i 0         2 + i 3         1 + i 1
clog          1 + i 0         -               1 + i 1         1 + i 1         1 + i 0
clogl         -               -               1 + i 1         1 + i 2         1 + i 2
clog10f       2 + i 1         -               1 + i 1         2 + i 1         2 + i 1
clog10        2 + i 1         -               1 + i 1         2 + i 1         2 + i 1
clog10l       -               -               1 + i 1         2 + i 2         2 + i 2
conjf         -               -               -               -               -
conj          -               -               -               -               -
conjl         -               -               -               -               -
copysignf     -               -               -               -               -
copysign      -               -               -               -               -
copysignl     -               -               -               -               -
cosf          1               -               -               1               1
cos           -               -               -               2               -
cosl          -               -               1               2               2
coshf         1               -               -               1               1
cosh          1               -               -               1               1
coshl         -               -               2               3               3
cpowf         4 + i 2         -               5 + i 1         5 + i 2         4 + i 2
cpow          2 + i 0         -               2 + i 1         2 + i 2         2 + i 0
cpowl         -               -               3 + i 4         4 + i 2         4 + i 1
cprojf        -               -               -               -               -
cproj         -               -               -               -               -
cprojl        -               -               -               0 + i 1         -
crealf        -               -               -               -               -
creal         -               -               -               -               -
creall        -               -               -               -               -
csinf         1 + i 0         -               1 + i 1         1 + i 0         1 + i 0
csin          1 + i 0         -               1 + i 1         1 + i 0         1 + i 0
csinl         -               -               1 + i 0         1 + i 1         2 + i 1
csinhf        1 + i 1         -               1 + i 1         1 + i 1         1 + i 1
csinh         0 + i 1         -               1 + i 1         0 + i 1         0 + i 1
csinhl        -               -               1 + i 0         1 + i 1         1 + i 2
csqrtf        1 + i 1         -               -               2 + i 2         1 + i 1
csqrt         1 + i 1         -               1 + i 0         1 + i 1         1 + i 1
csqrtl        -               -               1 + i 1         1 + i 1         1 + i 1
ctanf         1 + i 1         -               1 + i 1         1 + i 1         1 + i 1
ctan          1 + i 2         -               1 + i 1         1 + i 2         1 + i 2
ctanl         -               -               2 + i 1         2 + i 2         2 + i 2
ctanhf        1 + i 2         -               1 + i 1         2 + i 1         1 + i 2
ctanh         2 + i 2         -               1 + i 1         2 + i 2         2 + i 2
ctanhl        -               -               1 + i 2         2 + i 3         2 + i 3
erff          -               -               -               -               -
erf           1               -               1               1               1
erfl          -               -               1               1               1
erfcf         1               -               -               1               1
erfc          1               -               1               1               1
erfcl         -               -               1               2               2
expf          -               -               -               -               -
exp           -               -               -               -               -
expl          -               -               -               1               1
exp10f        -               -               -               1               -
exp10         1               -               -               1               1
exp10l        -               -               1               1               1
exp2f         -               -               -               -               -
exp2          -               -               -               -               -
exp2l         -               -               -               2               -
expm1f        1               -               -               1               1
expm1         1               -               -               1               1
expm1l        -               -               1               1               1
fabsf         -               -               -               -               -
fabs          -               -               -               -               -
fabsl         -               -               -               -               -
fdimf         -               -               -               -               -
fdim          -               -               -               -               -
fdiml         -               -               -               -               -
floorf        -               -               -               -               -
floor         -               -               -               -               -
floorl        -               -               -               -               -
fmaf          -               -               -               -               -
fma           -               -               -               -               -
fmal          -               -               -               -               -
fmaxf         -               -               -               -               -
fmax          -               -               -               -               -
fmaxl         -               -               -               -               -
fminf         -               -               -               -               -
fmin          -               -               -               -               -
fminl         -               -               -               -               -
fmodf         -               -               -               -               -
fmod          -               -               -               -               -
fmodl         -               -               -               -               -
frexpf        -               -               -               -               -
frexp         -               -               -               -               -
frexpl        -               -               -               -               -
gammaf        1               -               1               2               1
gamma         1               -               1               1               1
gammal        -               -               1               1               1
hypotf        -               -               -               1               -
hypot         1               -               -               1               1
hypotl        -               -               1               1               1
ilogbf        -               -               -               -               -
ilogb         -               -               -               -               -
ilogbl        -               -               -               -               -
j0f           2               -               1               2               2
j0            2               -               1               3               2
j0l           -               -               2               2               2
j1f           2               -               1               2               2
j1            1               -               2               1               1
j1l           -               -               1               1               1
jnf           4               -               3               5               4
jn            4               -               2               4               4
jnl           -               -               4               7               4
lgammaf       1               -               1               2               1
lgamma        1               -               1               1               1
lgammal       -               -               1               1               1
lrintf        -               -               -               -               -
lrint         -               -               -               -               -
lrintl        -               -               -               -               -
llrintf       -               -               -               -               -
llrint        -               -               -               -               -
llrintl       -               -               -               -               -
logf          1               -               -               1               1
log           -               -               -               -               -
logl          -               -               1               1               1
log10f        2               -               -               2               2
log10         1               -               -               1               1
log10l        -               -               1               1               1
log1pf        1               -               -               1               1
log1p         -               -               -               -               -
log1pl        -               -               1               1               1
log2f         -               -               -               -               -
log2          -               -               -               -               -
log2l         -               -               -               1               1
logbf         -               -               -               -               -
logb          -               -               -               -               -
logbl         -               -               -               -               -
lroundf       -               -               -               -               -
lround        -               -               -               -               -
lroundl       -               -               -               -               -
llroundf      -               -               -               -               -
llround       -               -               -               -               -
llroundl      -               -               -               -               -
modff         -               -               -               -               -
modf          -               -               -               -               -
modfl         -               -               -               -               -
nearbyintf    -               -               -               -               -
nearbyint     -               -               -               -               -
nearbyintl    -               -               -               -               -
nextafterf    -               -               -               -               -
nextafter     -               -               -               -               -
nextafterl    -               -               -               -               -
nexttowardf   -               -               -               -               -
nexttoward    -               -               -               -               -
nexttowardl   -               -               -               -               -
powf          1               -               -               1               1
pow           -               -               -               -               -
powl          -               -               1               1               1
remainderf    -               -               -               -               -
remainder     -               -               -               -               -
remainderl    -               -               -               -               -
remquof       -               -               -               -               -
remquo        -               -               -               -               -
remquol       -               -               -               -               -
rintf         -               -               -               -               -
rint          -               -               -               -               -
rintl         -               -               -               -               -
roundf        -               -               -               -               -
round         -               -               -               -               -
roundl        -               -               -               -               -
scalbf        -               -               -               -               -
scalb         -               -               -               -               -
scalbl        -               -               -               -               -
scalbnf       -               -               -               -               -
scalbn        -               -               -               -               -
scalbnl       -               -               -               -               -
scalblnf      -               -               -               -               -
scalbln       -               -               -               -               -
scalblnl      -               -               -               -               -
sinf          1               -               -               1               1
sin           -               -               -               -               -
sinl          -               -               1               1               1
sincosf       1               -               -               1               1
sincos        -               -               -               1               -
sincosl       -               -               1               1               1
sinhf         -               -               -               -               -
sinh          -               -               -               -               -
sinhl         -               -               -               1               1
sqrtf         -               -               -               -               -
sqrt          -               -               -               1               -
sqrtl         -               -               -               1               -
tanf          -               -               1               -               -
tan           -               -               -               1               -
tanl          -               -               1               2               2
tanhf         -               -               -               -               -
tanh          -               -               -               -               -
tanhl         -               -               -               1               1
tgammaf       3               -               2               3               3
tgamma        4               -               4               4               4
tgammal       -               -               4               3               3
truncf        -               -               -               -               -
trunc         -               -               -               -               -
truncl        -               -               -               -               -
y0f           1               -               1               1               1
y0            2               -               1               2               2
y0l           -               -               1               1               1
y1f           2               -               2               2               2
y1            3               -               2               3               3
y1l           -               -               2               2               2
ynf           2               -               3               2               2
yn            3               -               2               3               3
ynl           -               -               4               2               2
Function      S/390           sh              sparc/fpu       x86_64/fpu
acosf         -               -               -               -
acos          -               -               -               -
acosl         -               -               -               1
acoshf        -               -               -               -
acosh         1               1               1               1
acoshl        1               -               1               -
asinf         -               -               -               -
asin          -               -               -               -
asinl         1               -               1               -
asinhf        1               1               1               1
asinh         1               1               1               1
asinhl        1               -               1               1
atanf         -               -               -               -
atan          1               -               -               -
atanl         -               -               -               -
atanhf        1               1               1               1
atanh         -               -               -               -
atanhl        1               -               1               1
atan2f        1               1               1               1
atan2         -               -               -               -
atan2l        1               -               1               1
cabsf         -               -               -               -
cabs          -               -               -               -
cabsl         -               -               -               -
cacosf        2 + i 2         2 + i 2         2 + i 2         2 + i 2
cacos         1 + i 1         1 + i 1         1 + i 1         1 + i 1
cacosl        2 + i 2         -               2 + i 2         1 + i 2
cacoshf       2 + i 2         2 + i 2         2 + i 2         2 + i 2
cacosh        1 + i 1         1 + i 1         1 + i 1         1 + i 1
cacoshl       2 + i 2         -               2 + i 2         2 + i 1
cargf         -               -               -               -
carg          -               -               -               -
cargl         -               -               -               -
casinf        1 + i 2         1 + i 2         1 + i 2         1 + i 2
casin         1 + i 1         1 + i 1         1 + i 1         1 + i 1
casinl        2 + i 2         -               2 + i 2         1 + i 2
casinhf       2 + i 1         2 + i 1         2 + i 1         2 + i 1
casinh        1 + i 1         1 + i 1         1 + i 1         1 + i 1
casinhl       2 + i 2         -               2 + i 2         2 + i 1
catanf        1 + i 1         1 + i 1         1 + i 1         1 + i 1
catan         0 + i 1         0 + i 1         0 + i 1         0 + i 1
catanl        1 + i 1         -               1 + i 1         0 + i 1
catanhf       1 + i 1         1 + i 1         1 + i 1         1 + i 1
catanh        1 + i 0         1 + i 0         1 + i 0         1 + i 0
catanhl       1 + i 1         -               1 + i 1         1 + i 0
cbrtf         1               1               1               1
cbrt          1               1               1               1
cbrtl         1               -               1               1
ccosf         1 + i 1         1 + i 1         1 + i 1         1 + i 1
ccos          1 + i 1         1 + i 1         1 + i 1         1 + i 1
ccosl         1 + i 1         -               1 + i 1         1 + i 1
ccoshf        1 + i 1         1 + i 1         1 + i 1         1 + i 1
ccosh         1 + i 1         1 + i 1         1 + i 1         1 + i 1
ccoshl        1 + i 1         -               1 + i 1         0 + i 1
ceilf         -               -               -               -
ceil          -               -               -               -
ceill         -               -               -               -
cexpf         1 + i 2         1 + i 2         1 + i 2         1 + i 2
cexp          2 + i 1         2 + i 1         2 + i 1         2 + i 1
cexpl         1 + i 1         -               1 + i 1         1 + i 1
cimagf        -               -               -               -
cimag         -               -               -               -
cimagl        -               -               -               -
clogf         1 + i 1         1 + i 1         1 + i 1         1 + i 1
clog          1 + i 1         1 + i 0         1 + i 0         1 + i 0
clogl         1 + i 1         -               1 + i 1         1 + i 1
clog10f       2 + i 1         2 + i 1         2 + i 1         2 + i 1
clog10        2 + i 1         2 + i 1         2 + i 1         2 + i 1
clog10l       1 + i 2         -               1 + i 2         1 + i 1
conjf         -               -               -               -
conj          -               -               -               -
conjl         -               -               -               -
copysignf     -               -               -               -
copysign      -               -               -               -
copysignl     -               -               -               -
cosf          1               1               1               -
cos           -               -               -               -
cosl          1               -               1               1
coshf         1               1               1               1
cosh          1               1               1               1
coshl         1               -               1               2
cpowf         5 + i 2         4 + i 2         4 + i 2         5 + i 2
cpow          2 + i 0         2 + i 0         2 + i 0         2 + i 0
cpowl         4 + i 1         -               4 + i 1         3 + i 4
cprojf        -               -               -               -
cproj         -               -               -               -
cprojl        -               -               -               -
crealf        -               -               -               -
creal         -               -               -               -
creall        -               -               -               -
csinf         1 + i 0         1 + i 0         1 + i 0         1 + i 0
csin          1 + i 0         1 + i 0         1 + i 0         1 + i 0
csinl         1 + i 1         -               1 + i 1         1 + i 0
csinhf        1 + i 1         1 + i 1         1 + i 1         1 + i 1
csinh         0 + i 1         0 + i 1         0 + i 1         0 + i 1
csinhl        1 + i 1         -               1 + i 1         1 + i 0
csqrtf        1 + i 1         1 + i 1         1 + i 1         1 + i 1
csqrt         1 + i 1         1 + i 1         1 + i 1         1 + i 1
csqrtl        1 + i 1         -               1 + i 1         1 + i 1
ctanf         1 + i 1         1 + i 1         1 + i 1         1 + i 2
ctan          1 + i 2         1 + i 2         1 + i 2         1 + i 2
ctanl         3 + i 3         -               3 + i 3         2 + i 1
ctanhf        2 + i 1         1 + i 2         1 + i 2         2 + i 2
ctanh         2 + i 2         2 + i 2         2 + i 2         2 + i 2
ctanhl        3 + i 3         -               3 + i 3         1 + i 2
erff          -               -               -               -
erf           1               1               1               1
erfl          1               -               1               1
erfcf         1               1               1               1
erfc          1               1               1               1
erfcl         1               -               1               1
expf          -               -               -               -
exp           -               -               -               -
expl          -               -               -               -
exp10f        -               -               -               -
exp10         1               1               1               1
exp10l        1               -               1               1
exp2f         -               -               -               -
exp2          -               -               -               -
exp2l         1               -               1               -
expm1f        1               1               1               1
expm1         1               1               1               1
expm1l        1               -               1               1
fabsf         -               -               -               -
fabs          -               -               -               -
fabsl         -               -               -               -
fdimf         -               -               -               -
fdim          -               -               -               -
fdiml         -               -               -               -
floorf        -               -               -               -
floor         -               -               -               -
floorl        -               -               -               -
fmaf          -               -               -               -
fma           -               -               -               -
fmal          -               -               -               -
fmaxf         -               -               -               -
fmax          -               -               -               -
fmaxl         -               -               -               -
fminf         -               -               -               -
fmin          -               -               -               -
fminl         -               -               -               -
fmodf         -               -               -               -
fmod          -               -               -               -
fmodl         -               -               -               -
frexpf        -               -               -               -
frexp         -               -               -               -
frexpl        -               -               -               -
gammaf        1               1               1               1
gamma         1               1               1               1
gammal        1               -               1               1
hypotf        -               -               -               -
hypot         1               1               1               1
hypotl        1               -               1               1
ilogbf        -               -               -               -
ilogb         -               -               -               -
ilogbl        -               -               -               -
j0f           2               2               2               2
j0            2               2               2               2
j0l           2               -               2               2
j1f           2               2               2               2
j1            1               1               1               1
j1l           4               -               4               1
jnf           4               4               4               4
jn            4               4               4               4
jnl           7               -               7               4
lgammaf       1               1               1               1
lgamma        1               1               1               1
lgammal       1               -               1               1
lrintf        -               -               -               -
lrint         -               -               -               -
lrintl        -               -               -               -
llrintf       -               -               -               -
llrint        -               -               -               -
llrintl       -               -               -               -
logf          1               1               1               1
log           -               -               -               -
logl          1               -               1               1
log10f        2               2               2               2
log10         1               1               1               1
log10l        1               -               1               1
log1pf        1               1               1               1
log1p         -               -               -               -
log1pl        1               -               1               1
log2f         -               -               -               -
log2          -               -               -               -
log2l         1               -               1               -
logbf         -               -               -               -
logb          -               -               -               -
logbl         -               -               -               -
lroundf       -               -               -               -
lround        -               -               -               -
lroundl       -               -               -               -
llroundf      -               -               -               -
llround       -               -               -               -
llroundl      -               -               -               -
modff         -               -               -               -
modf          -               -               -               -
modfl         -               -               -               -
nearbyintf    -               -               -               -
nearbyint     -               -               -               -
nearbyintl    -               -               -               -
nextafterf    -               -               -               -
nextafter     -               -               -               -
nextafterl    -               -               -               -
nexttowardf   -               -               -               -
nexttoward    -               -               -               -
nexttowardl   -               -               -               -
powf          1               1               1               1
pow           -               -               -               -
powl          1               -               1               1
remainderf    -               -               -               -
remainder     -               -               -               -
remainderl    -               -               -               -
remquof       -               -               -               -
remquo        -               -               -               -
remquol       -               -               -               -
rintf         -               -               -               -
rint          -               -               -               -
rintl         -               -               -               -
roundf        -               -               -               -
round         -               -               -               -
roundl        -               -               -               -
scalbf        -               -               -               -
scalb         -               -               -               -
scalbl        -               -               -               -
scalbnf       -               -               -               -
scalbn        -               -               -               -
scalbnl       -               -               -               -
scalblnf      -               -               -               -
scalbln       -               -               -               -
scalblnl      -               -               -               -
sinf          1               1               1               -
sin           -               -               -               -
sinl          1               -               1               1
sincosf       1               1               1               -
sincos        -               -               -               -
sincosl       1               -               1               1
sinhf         -               -               -               -
sinh          -               -               -               -
sinhl         -               -               -               1
sqrtf         -               -               -               -
sqrt          -               -               -               -
sqrtl         -               -               -               -
tanf          -               -               -               -
tan           -               -               -               -
tanl          1               -               1               1
tanhf         -               -               -               -
tanh          -               -               -               -
tanhl         1               -               1               -
tgammaf       3               3               3               3
tgamma        4               4               4               4
tgammal       4               -               4               4
truncf        -               -               -               -
trunc         -               -               -               -
truncl        -               -               -               -
y0f           1               1               1               1
y0            2               2               2               2
y0l           3               -               3               1
y1f           2               2               2               2
y1            3               3               3               3
y1l           2               -               2               2
ynf           2               2               2               3
yn            3               3               3               3
ynl           4               -               4               4


File: libc.info,  Node: Pseudo-Random Numbers,  Next: FP Function Optimizations,  Prev: Errors in Math Functions,  Up: Mathematics

19.8 Pseudo-Random Numbers
==========================

This section describes the GNU facilities for generating a series of
pseudo-random numbers.  The numbers generated are not truly random;
typically, they form a sequence that repeats periodically, with a period
so large that you can ignore it for ordinary purposes.  The random
number generator works by remembering a "seed" value which it uses to
compute the next random number and also to compute a new seed.

   Although the generated numbers look unpredictable within one run of a
program, the sequence of numbers is _exactly the same_ from one run to
the next.  This is because the initial seed is always the same.  This is
convenient when you are debugging a program, but it is unhelpful if you
want the program to behave unpredictably.  If you want a different
pseudo-random series each time your program runs, you must specify a
different seed each time.  For ordinary purposes, basing the seed on the
current time works well.

   You can obtain repeatable sequences of numbers on a particular
machine type by specifying the same initial seed value for the random
number generator.  There is no standard meaning for a particular seed
value; the same seed, used in different C libraries or on different CPU
types, will give you different random numbers.

   The GNU C Library supports the standard ISO C random number functions
plus two other sets derived from BSD and SVID. The BSD and ISO C
functions provide identical, somewhat limited functionality.  If only a
small number of random bits are required, we recommend you use the ISO C
interface, 'rand' and 'srand'.  The SVID functions provide a more
flexible interface, which allows better random number generator
algorithms, provides more random bits (up to 48) per call, and can
provide random floating-point numbers.  These functions are required by
the XPG standard and therefore will be present in all modern Unix
systems.

* Menu:

* ISO Random::                  'rand' and friends.
* BSD Random::                  'random' and friends.
* SVID Random::                 'drand48' and friends.


File: libc.info,  Node: ISO Random,  Next: BSD Random,  Up: Pseudo-Random Numbers

19.8.1 ISO C Random Number Functions
------------------------------------

This section describes the random number functions that are part of the ISO C
standard.

   To use these facilities, you should include the header file
'stdlib.h' in your program.

 -- Macro: int RAND_MAX
     The value of this macro is an integer constant representing the
     largest value the 'rand' function can return.  In the GNU C
     Library, it is '2147483647', which is the largest signed integer
     representable in 32 bits.  In other libraries, it may be as low as
     '32767'.

 -- Function: int rand (void)
     Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock | *Note
     POSIX Safety Concepts::.

     The 'rand' function returns the next pseudo-random number in the
     series.  The value ranges from '0' to 'RAND_MAX'.

 -- Function: void srand (unsigned int SEED)
     Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock | *Note
     POSIX Safety Concepts::.

     This function establishes SEED as the seed for a new series of
     pseudo-random numbers.  If you call 'rand' before a seed has been
     established with 'srand', it uses the value '1' as a default seed.

     To produce a different pseudo-random series each time your program
     is run, do 'srand (time (0))'.

   POSIX.1 extended the C standard functions to support reproducible
random numbers in multi-threaded programs.  However, the extension is
badly designed and unsuitable for serious work.

 -- Function: int rand_r (unsigned int *SEED)
     Preliminary: | MT-Safe | AS-Safe | AC-Safe | *Note POSIX Safety
     Concepts::.

     This function returns a random number in the range 0 to 'RAND_MAX'
     just as 'rand' does.  However, all its state is stored in the SEED
     argument.  This means the RNG's state can only have as many bits as
     the type 'unsigned int' has.  This is far too few to provide a good
     RNG.

     If your program requires a reentrant RNG, we recommend you use the
     reentrant GNU extensions to the SVID random number generator.  The
     POSIX.1 interface should only be used when the GNU extensions are
     not available.


File: libc.info,  Node: BSD Random,  Next: SVID Random,  Prev: ISO Random,  Up: Pseudo-Random Numbers

19.8.2 BSD Random Number Functions
----------------------------------

This section describes a set of random number generation functions that
are derived from BSD. There is no advantage to using these functions
with the GNU C Library; we support them for BSD compatibility only.

   The prototypes for these functions are in 'stdlib.h'.

 -- Function: long int random (void)
     Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock | *Note
     POSIX Safety Concepts::.

     This function returns the next pseudo-random number in the
     sequence.  The value returned ranges from '0' to '2147483647'.

     *NB:* Temporarily this function was defined to return a 'int32_t'
     value to indicate that the return value always contains 32 bits
     even if 'long int' is wider.  The standard demands it differently.
     Users must always be aware of the 32-bit limitation, though.

 -- Function: void srandom (unsigned int SEED)
     Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock | *Note
     POSIX Safety Concepts::.

     The 'srandom' function sets the state of the random number
     generator based on the integer SEED.  If you supply a SEED value of
     '1', this will cause 'random' to reproduce the default set of
     random numbers.

     To produce a different set of pseudo-random numbers each time your
     program runs, do 'srandom (time (0))'.

 -- Function: char * initstate (unsigned int SEED, char *STATE, size_t
          SIZE)
     Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock | *Note
     POSIX Safety Concepts::.

     The 'initstate' function is used to initialize the random number
     generator state.  The argument STATE is an array of SIZE bytes,
     used to hold the state information.  It is initialized based on
     SEED.  The size must be between 8 and 256 bytes, and should be a
     power of two.  The bigger the STATE array, the better.

     The return value is the previous value of the state information
     array.  You can use this value later as an argument to 'setstate'
     to restore that state.

 -- Function: char * setstate (char *STATE)
     Preliminary: | MT-Safe | AS-Unsafe lock | AC-Unsafe lock | *Note
     POSIX Safety Concepts::.

     The 'setstate' function restores the random number state
     information STATE.  The argument must have been the result of a
     previous call to INITSTATE or SETSTATE.

     The return value is the previous value of the state information
     array.  You can use this value later as an argument to 'setstate'
     to restore that state.

     If the function fails the return value is 'NULL'.

   The four functions described so far in this section all work on a
state which is shared by all threads.  The state is not directly
accessible to the user and can only be modified by these functions.
This makes it hard to deal with situations where each thread should have
its own pseudo-random number generator.

   The GNU C Library contains four additional functions which contain
the state as an explicit parameter and therefore make it possible to
handle thread-local PRNGs.  Beside this there is no difference.  In
fact, the four functions already discussed are implemented internally
using the following interfaces.

   The 'stdlib.h' header contains a definition of the following type:

 -- Data Type: struct random_data

     Objects of type 'struct random_data' contain the information
     necessary to represent the state of the PRNG. Although a complete
     definition of the type is present the type should be treated as
     opaque.

   The functions modifying the state follow exactly the already
described functions.

 -- Function: int random_r (struct random_data *restrict BUF, int32_t
          *restrict RESULT)
     Preliminary: | MT-Safe race:buf | AS-Safe | AC-Unsafe corrupt |
     *Note POSIX Safety Concepts::.

     The 'random_r' function behaves exactly like the 'random' function
     except that it uses and modifies the state in the object pointed to
     by the first parameter instead of the global state.

 -- Function: int srandom_r (unsigned int SEED, struct random_data *BUF)
     Preliminary: | MT-Safe race:buf | AS-Safe | AC-Unsafe corrupt |
     *Note POSIX Safety Concepts::.

     The 'srandom_r' function behaves exactly like the 'srandom'
     function except that it uses and modifies the state in the object
     pointed to by the second parameter instead of the global state.

 -- Function: int initstate_r (unsigned int SEED, char *restrict
          STATEBUF, size_t STATELEN, struct random_data *restrict BUF)
     Preliminary: | MT-Safe race:buf | AS-Safe | AC-Unsafe corrupt |
     *Note POSIX Safety Concepts::.

     The 'initstate_r' function behaves exactly like the 'initstate'
     function except that it uses and modifies the state in the object
     pointed to by the fourth parameter instead of the global state.

 -- Function: int setstate_r (char *restrict STATEBUF, struct
          random_data *restrict BUF)
     Preliminary: | MT-Safe race:buf | AS-Safe | AC-Unsafe corrupt |
     *Note POSIX Safety Concepts::.

     The 'setstate_r' function behaves exactly like the 'setstate'
     function except that it uses and modifies the state in the object
     pointed to by the first parameter instead of the global state.


File: libc.info,  Node: SVID Random,  Prev: BSD Random,  Up: Pseudo-Random Numbers

19.8.3 SVID Random Number Function
----------------------------------

The C library on SVID systems contains yet another kind of random number
generator functions.  They use a state of 48 bits of data.  The user can
choose among a collection of functions which return the random bits in
different forms.

   Generally there are two kinds of function.  The first uses a state of
the random number generator which is shared among several functions and
by all threads of the process.  The second requires the user to handle
the state.

   All functions have in common that they use the same congruential
formula with the same constants.  The formula is

     Y = (a * X + c) mod m

where X is the state of the generator at the beginning and Y the state
at the end.  'a' and 'c' are constants determining the way the generator
works.  By default they are

     a = 0x5DEECE66D = 25214903917
     c = 0xb = 11

but they can also be changed by the user.  'm' is of course 2^48 since
the state consists of a 48-bit array.

   The prototypes for these functions are in 'stdlib.h'.

 -- Function: double drand48 (void)
     Preliminary: | MT-Unsafe race:drand48 | AS-Unsafe | AC-Unsafe
     corrupt | *Note POSIX Safety Concepts::.

     This function returns a 'double' value in the range of '0.0' to
     '1.0' (exclusive).  The random bits are determined by the global
     state of the random number generator in the C library.

     Since the 'double' type according to IEEE 754 has a 52-bit mantissa
     this means 4 bits are not initialized by the random number
     generator.  These are (of course) chosen to be the least
     significant bits and they are initialized to '0'.

 -- Function: double erand48 (unsigned short int XSUBI[3])
     Preliminary: | MT-Unsafe race:drand48 | AS-Unsafe | AC-Unsafe
     corrupt | *Note POSIX Safety Concepts::.

     This function returns a 'double' value in the range of '0.0' to
     '1.0' (exclusive), similarly to 'drand48'.  The argument is an
     array describing the state of the random number generator.

     This function can be called subsequently since it updates the array
     to guarantee random numbers.  The array should have been
     initialized before initial use to obtain reproducible results.

 -- Function: long int lrand48 (void)
     Preliminary: | MT-Unsafe race:drand48 | AS-Unsafe | AC-Unsafe
     corrupt | *Note POSIX Safety Concepts::.

     The 'lrand48' function returns an integer value in the range of '0'
     to '2^31' (exclusive).  Even if the size of the 'long int' type can
     take more than 32 bits, no higher numbers are returned.  The random
     bits are determined by the global state of the random number
     generator in the C library.

 -- Function: long int nrand48 (unsigned short int XSUBI[3])
     Preliminary: | MT-Unsafe race:drand48 | AS-Unsafe | AC-Unsafe
     corrupt | *Note POSIX Safety Concepts::.

     This function is similar to the 'lrand48' function in that it
     returns a number in the range of '0' to '2^31' (exclusive) but the
     state of the random number generator used to produce the random
     bits is determined by the array provided as the parameter to the
     function.

     The numbers in the array are updated afterwards so that subsequent
     calls to this function yield different results (as is expected of a
     random number generator).  The array should have been initialized
     before the first call to obtain reproducible results.

 -- Function: long int mrand48 (void)
     Preliminary: | MT-Unsafe race:drand48 | AS-Unsafe | AC-Unsafe
     corrupt | *Note POSIX Safety Concepts::.

     The 'mrand48' function is similar to 'lrand48'.  The only
     difference is that the numbers returned are in the range '-2^31' to
     '2^31' (exclusive).

 -- Function: long int jrand48 (unsigned short int XSUBI[3])
     Preliminary: | MT-Unsafe race:drand48 | AS-Unsafe | AC-Unsafe
     corrupt | *Note POSIX Safety Concepts::.

     The 'jrand48' function is similar to 'nrand48'.  The only
     difference is that the numbers returned are in the range '-2^31' to
     '2^31' (exclusive).  For the 'xsubi' parameter the same
     requirements are necessary.

   The internal state of the random number generator can be initialized
in several ways.  The methods differ in the completeness of the
information provided.

 -- Function: void srand48 (long int SEEDVAL)
     Preliminary: | MT-Unsafe race:drand48 | AS-Unsafe | AC-Unsafe
     corrupt | *Note POSIX Safety Concepts::.

     The 'srand48' function sets the most significant 32 bits of the
     internal state of the random number generator to the least
     significant 32 bits of the SEEDVAL parameter.  The lower 16 bits
     are initialized to the value '0x330E'.  Even if the 'long int' type
     contains more than 32 bits only the lower 32 bits are used.

     Owing to this limitation, initialization of the state of this
     function is not very useful.  But it makes it easy to use a
     construct like 'srand48 (time (0))'.

     A side-effect of this function is that the values 'a' and 'c' from
     the internal state, which are used in the congruential formula, are
     reset to the default values given above.  This is of importance
     once the user has called the 'lcong48' function (see below).

 -- Function: unsigned short int * seed48 (unsigned short int
          SEED16V[3])
     Preliminary: | MT-Unsafe race:drand48 | AS-Unsafe | AC-Unsafe
     corrupt | *Note POSIX Safety Concepts::.

     The 'seed48' function initializes all 48 bits of the state of the
     internal random number generator from the contents of the parameter
     SEED16V.  Here the lower 16 bits of the first element of SEE16V
     initialize the least significant 16 bits of the internal state, the
     lower 16 bits of 'SEED16V[1]' initialize the mid-order 16 bits of
     the state and the 16 lower bits of 'SEED16V[2]' initialize the most
     significant 16 bits of the state.

     Unlike 'srand48' this function lets the user initialize all 48 bits
     of the state.

     The value returned by 'seed48' is a pointer to an array containing
     the values of the internal state before the change.  This might be
     useful to restart the random number generator at a certain state.
     Otherwise the value can simply be ignored.

     As for 'srand48', the values 'a' and 'c' from the congruential
     formula are reset to the default values.

   There is one more function to initialize the random number generator
which enables you to specify even more information by allowing you to
change the parameters in the congruential formula.

 -- Function: void lcong48 (unsigned short int PARAM[7])
     Preliminary: | MT-Unsafe race:drand48 | AS-Unsafe | AC-Unsafe
     corrupt | *Note POSIX Safety Concepts::.

     The 'lcong48' function allows the user to change the complete state
     of the random number generator.  Unlike 'srand48' and 'seed48',
     this function also changes the constants in the congruential
     formula.

     From the seven elements in the array PARAM the least significant 16
     bits of the entries 'PARAM[0]' to 'PARAM[2]' determine the initial
     state, the least significant 16 bits of 'PARAM[3]' to 'PARAM[5]'
     determine the 48 bit constant 'a' and 'PARAM[6]' determines the
     16-bit value 'c'.

   All the above functions have in common that they use the global
parameters for the congruential formula.  In multi-threaded programs it
might sometimes be useful to have different parameters in different
threads.  For this reason all the above functions have a counterpart
which works on a description of the random number generator in the
user-supplied buffer instead of the global state.

   Please note that it is no problem if several threads use the global
state if all threads use the functions which take a pointer to an array
containing the state.  The random numbers are computed following the
same loop but if the state in the array is different all threads will
obtain an individual random number generator.

   The user-supplied buffer must be of type 'struct drand48_data'.  This
type should be regarded as opaque and not manipulated directly.

 -- Function: int drand48_r (struct drand48_data *BUFFER, double
          *RESULT)
     Preliminary: | MT-Safe race:buffer | AS-Safe | AC-Unsafe corrupt |
     *Note POSIX Safety Concepts::.

     This function is equivalent to the 'drand48' function with the
     difference that it does not modify the global random number
     generator parameters but instead the parameters in the buffer
     supplied through the pointer BUFFER.  The random number is returned
     in the variable pointed to by RESULT.

     The return value of the function indicates whether the call
     succeeded.  If the value is less than '0' an error occurred and
     ERRNO is set to indicate the problem.

     This function is a GNU extension and should not be used in portable
     programs.

 -- Function: int erand48_r (unsigned short int XSUBI[3], struct
          drand48_data *BUFFER, double *RESULT)
     Preliminary: | MT-Safe race:buffer | AS-Safe | AC-Unsafe corrupt |
     *Note POSIX Safety Concepts::.

     The 'erand48_r' function works like 'erand48', but in addition it
     takes an argument BUFFER which describes the random number
     generator.  The state of the random number generator is taken from
     the 'xsubi' array, the parameters for the congruential formula from
     the global random number generator data.  The random number is
     returned in the variable pointed to by RESULT.

     The return value is non-negative if the call succeeded.

     This function is a GNU extension and should not be used in portable
     programs.

 -- Function: int lrand48_r (struct drand48_data *BUFFER, long int
          *RESULT)
     Preliminary: | MT-Safe race:buffer | AS-Safe | AC-Unsafe corrupt |
     *Note POSIX Safety Concepts::.

     This function is similar to 'lrand48', but in addition it takes a
     pointer to a buffer describing the state of the random number
     generator just like 'drand48'.

     If the return value of the function is non-negative the variable
     pointed to by RESULT contains the result.  Otherwise an error
     occurred.

     This function is a GNU extension and should not be used in portable
     programs.

 -- Function: int nrand48_r (unsigned short int XSUBI[3], struct
          drand48_data *BUFFER, long int *RESULT)
     Preliminary: | MT-Safe race:buffer | AS-Safe | AC-Unsafe corrupt |
     *Note POSIX Safety Concepts::.

     The 'nrand48_r' function works like 'nrand48' in that it produces a
     random number in the range '0' to '2^31'.  But instead of using the
     global parameters for the congruential formula it uses the
     information from the buffer pointed to by BUFFER.  The state is
     described by the values in XSUBI.

     If the return value is non-negative the variable pointed to by
     RESULT contains the result.

     This function is a GNU extension and should not be used in portable
     programs.

 -- Function: int mrand48_r (struct drand48_data *BUFFER, long int
          *RESULT)
     Preliminary: | MT-Safe race:buffer | AS-Safe | AC-Unsafe corrupt |
     *Note POSIX Safety Concepts::.

     This function is similar to 'mrand48' but like the other reentrant
     functions it uses the random number generator described by the
     value in the buffer pointed to by BUFFER.

     If the return value is non-negative the variable pointed to by
     RESULT contains the result.

     This function is a GNU extension and should not be used in portable
     programs.

 -- Function: int jrand48_r (unsigned short int XSUBI[3], struct
          drand48_data *BUFFER, long int *RESULT)
     Preliminary: | MT-Safe race:buffer | AS-Safe | AC-Unsafe corrupt |
     *Note POSIX Safety Concepts::.

     The 'jrand48_r' function is similar to 'jrand48'.  Like the other
     reentrant functions of this function family it uses the
     congruential formula parameters from the buffer pointed to by
     BUFFER.

     If the return value is non-negative the variable pointed to by
     RESULT contains the result.

     This function is a GNU extension and should not be used in portable
     programs.

   Before any of the above functions are used the buffer of type 'struct
drand48_data' should be initialized.  The easiest way to do this is to
fill the whole buffer with null bytes, e.g.  by

     memset (buffer, '\0', sizeof (struct drand48_data));

Using any of the reentrant functions of this family now will
automatically initialize the random number generator to the default
values for the state and the parameters of the congruential formula.

   The other possibility is to use any of the functions which explicitly
initialize the buffer.  Though it might be obvious how to initialize the
buffer from looking at the parameter to the function, it is highly
recommended to use these functions since the result might not always be
what you expect.

 -- Function: int srand48_r (long int SEEDVAL, struct drand48_data
          *BUFFER)
     Preliminary: | MT-Safe race:buffer | AS-Safe | AC-Unsafe corrupt |
     *Note POSIX Safety Concepts::.

     The description of the random number generator represented by the
     information in BUFFER is initialized similarly to what the function
     'srand48' does.  The state is initialized from the parameter
     SEEDVAL and the parameters for the congruential formula are
     initialized to their default values.

     If the return value is non-negative the function call succeeded.

     This function is a GNU extension and should not be used in portable
     programs.

 -- Function: int seed48_r (unsigned short int SEED16V[3], struct
          drand48_data *BUFFER)
     Preliminary: | MT-Safe race:buffer | AS-Safe | AC-Unsafe corrupt |
     *Note POSIX Safety Concepts::.

     This function is similar to 'srand48_r' but like 'seed48' it
     initializes all 48 bits of the state from the parameter SEED16V.

     If the return value is non-negative the function call succeeded.
     It does not return a pointer to the previous state of the random
     number generator like the 'seed48' function does.  If the user
     wants to preserve the state for a later re-run s/he can copy the
     whole buffer pointed to by BUFFER.

     This function is a GNU extension and should not be used in portable
     programs.

 -- Function: int lcong48_r (unsigned short int PARAM[7], struct
          drand48_data *BUFFER)
     Preliminary: | MT-Safe race:buffer | AS-Safe | AC-Unsafe corrupt |
     *Note POSIX Safety Concepts::.

     This function initializes all aspects of the random number
     generator described in BUFFER with the data in PARAM.  Here it is
     especially true that the function does more than just copying the
     contents of PARAM and BUFFER.  More work is required and therefore
     it is important to use this function rather than initializing the
     random number generator directly.

     If the return value is non-negative the function call succeeded.

     This function is a GNU extension and should not be used in portable
     programs.


File: libc.info,  Node: FP Function Optimizations,  Prev: Pseudo-Random Numbers,  Up: Mathematics

19.9 Is Fast Code or Small Code preferred?
==========================================

If an application uses many floating point functions it is often the
case that the cost of the function calls themselves is not negligible.
Modern processors can often execute the operations themselves very fast,
but the function call disrupts the instruction pipeline.

   For this reason the GNU C Library provides optimizations for many of
the frequently-used math functions.  When GNU CC is used and the user
activates the optimizer, several new inline functions and macros are
defined.  These new functions and macros have the same names as the
library functions and so are used instead of the latter.  In the case of
inline functions the compiler will decide whether it is reasonable to
use them, and this decision is usually correct.

   This means that no calls to the library functions may be necessary,
and can increase the speed of generated code significantly.  The
drawback is that code size will increase, and the increase is not always
negligible.

   There are two kind of inline functions: Those that give the same
result as the library functions and others that might not set 'errno'
and might have a reduced precision and/or argument range in comparison
with the library functions.  The latter inline functions are only
available if the flag '-ffast-math' is given to GNU CC.

   In cases where the inline functions and macros are not wanted the
symbol '__NO_MATH_INLINES' should be defined before any system header is
included.  This will ensure that only library functions are used.  Of
course, it can be determined for each file in the project whether giving
this option is preferable or not.

   Not all hardware implements the entire IEEE 754 standard, and even if
it does there may be a substantial performance penalty for using some of
its features.  For example, enabling traps on some processors forces the
FPU to run un-pipelined, which can more than double calculation time.