gfiber / toolchains / bruno / 2b6f2ede586f74e5638097e93c6cd416cac5f860 / . / share / doc / mpfr / BUGS

Copyright 1999, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Free Software Foundation, Inc. | |

Contributed by the AriC and Caramel projects, INRIA. | |

This file is part of the GNU MPFR Library. | |

The GNU MPFR Library is free software; you can redistribute it and/or modify | |

it under the terms of the GNU Lesser General Public License as published by | |

the Free Software Foundation; either version 3 of the License, or (at your | |

option) any later version. | |

The GNU MPFR Library is distributed in the hope that it will be useful, but | |

WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY | |

or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public | |

License for more details. | |

You should have received a copy of the GNU Lesser General Public License | |

along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see | |

http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., | |

51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. | |

############################################################################## | |

Known bugs: | |

* The overflow/underflow exceptions may be badly handled in some functions; | |

specially when the intermediary internal results have exponent which | |

exceeds the hardware limit (2^30 for a 32 bits CPU, and 2^62 for a 64 bits | |

CPU) or the exact result is close to an overflow/underflow threshold. | |

* Under Linux/x86 with the traditional FPU, some functions do not work | |

if the FPU rounding precision has been changed to single (this is a | |

bad practice and should be useless, but one never knows what other | |

software will do). | |

* Some functions do not use MPFR_SAVE_EXPO_* macros, thus do not behave | |

correctly in a reduced exponent range. | |

* Function hypot gives incorrect result when on the one hand the difference | |

between parameters' exponents is near 2*MPFR_EMAX_MAX and on the other hand | |

the output precision or the precision of the parameter with greatest | |

absolute value is greater than 2*MPFR_EMAX_MAX-4. | |

Potential bugs: | |

* Possible incorrect results due to internal underflow, which can lead to | |

a huge loss of accuracy while the error analysis doesn't take that into | |

account. If the underflow occurs at the last function call (just before | |

the MPFR_CAN_ROUND), the result should be correct (or MPFR gets into an | |

infinite loop). TODO: check the code and the error analysis. | |

* Possible integer overflows on some machines. | |

* Possible bugs with huge precisions (> 2^30). | |

* Possible bugs if the chosen exponent range does not allow to represent | |

the range [1/16, 16]. | |

* Possible infinite loop in some functions for particular cases: when | |

the exact result is an exactly representable number or the middle of | |

consecutive two such numbers. However for non-algebraic functions, it is | |

believed that no such case exists, except the well-known cases like cos(0)=1, | |

exp(0)=1, and so on, and the x^y function when y is an integer or y=1/2^k. | |

* The mpfr_set_ld function may be quite slow if the long double type has an | |

exponent of more than 15 bits. | |

* mpfr_set_d may give wrong results on some non-IEEE architectures. | |

* Error analysis for some functions may be incorrect (out-of-date due | |

to modifications in the code?). | |

* Possible use of non-portable feature (pre-C99) of the integer division | |

with negative result. |