1Copyright 1999, 2001-2023 Free Software Foundation, Inc. 2Contributed by the AriC and Caramba projects, INRIA. 3 4This file is part of the GNU MPFR Library. 5 6The GNU MPFR Library is free software; you can redistribute it and/or modify 7it under the terms of the GNU Lesser General Public License as published by 8the Free Software Foundation; either version 3 of the License, or (at your 9option) any later version. 10 11The GNU MPFR Library is distributed in the hope that it will be useful, but 12WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 13or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 14License for more details. 15 16You should have received a copy of the GNU Lesser General Public License 17along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see 18https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., 1951 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. 20 21############################################################################## 22 23Known bugs: 24 25* The overflow/underflow exceptions may be badly handled in some functions; 26 specially when the intermediary internal results have exponent which 27 exceeds the hardware limit (2^30 for a 32 bits CPU, and 2^62 for a 64 bits 28 CPU) or the exact result is close to an overflow/underflow threshold. 29 30* Under Linux/x86 with the traditional FPU, some functions do not work 31 if the FPU rounding precision has been changed to single (this is a 32 bad practice and should be useless, but one never knows what other 33 software will do). 34 35* Some functions do not use MPFR_SAVE_EXPO_* macros, thus do not behave 36 correctly in a reduced exponent range. 37 38* Function hypot gives incorrect result when on the one hand the difference 39 between parameters' exponents is near 2*MPFR_EMAX_MAX and on the other hand 40 the output precision or the precision of the parameter with greatest 41 absolute value is greater than 2*MPFR_EMAX_MAX-4. 42 Note: Such huge precisions are not possible as they would be larger than 43 MPFR_PREC_MAX, unless the types for mpfr_exp_t and/or mpfr_prec_t are 44 changed (only for developers or expert users, not officially supported). 45 46Potential bugs: 47 48* Possible incorrect results due to internal underflow, which can lead to 49 a huge loss of accuracy while the error analysis doesn't take that into 50 account. If the underflow occurs at the last function call (just before 51 the MPFR_CAN_ROUND), the result should be correct (or MPFR gets into an 52 infinite loop). TODO: check the code and the error analysis. 53 54* Possible bugs with huge precisions (> 2^30) and a 32-bit ABI, in particular 55 undetected integer overflows. TODO: use the MPFR_ADD_PREC macro. 56 57* Possible bugs if the chosen exponent range does not allow to represent 58 the range [1/16, 16]. 59 60* Possible infinite loop in some functions for particular cases: when 61 the exact result is an exactly representable number or the middle of 62 consecutive two such numbers. However, for non-algebraic functions, it is 63 believed that no such case exists, except the well-known cases like cos(0)=1, 64 exp(0)=1, and so on, and the x^y function when y is an integer or y=1/2^k. 65 66* The mpfr_set_ld function may be quite slow if the long double type has an 67 exponent of more than 15 bits. 68 69* mpfr_set_d may give wrong results on some non-IEEE architectures. 70 71* Error analysis for some functions may be incorrect (out-of-date due 72 to modifications in the code?). 73 74* Possible use of non-portable feature (pre-C99) of the integer division 75 with negative result. 76