GNU MPFR 4.0.2 Release Candidate

The GNU MPFR 4.0.2 release candidate is available.

Patch 14 for GNU MPFR 4.0.1

Patch 14 of GNU MPFR 4.0.1 is available in the bugs section of the MPFR 4.0.1 page. It fixes a bug affecting the `mpfr_fmma`

and `mpfr_fmms`

functions in particular cases: in the round-to-nearest mode (`MPFR_RNDN`

), these functions can round in the wrong direction due to a double rounding in the computation.

Patches 12 and 13 for GNU MPFR 4.0.1

Patches 12 and 13 of GNU MPFR 4.0.1 are available in the bugs section of the MPFR 4.0.1 page. They fix bugs in the formatted output functions (`mpfr_*printf`

):

Patch 12: Possible undefined behavior in case of error: store to null pointer, free of bad pointer, and

`<stdarg.h>`related undefined behavior.Patch 13: The flags for the

`P`length modifier (`mpfr_prec_t`argument) are ignored; this includes the sign of the field width when the value is provided in argument (by using an asterisk`*`in the format string).

Patches 10 and 11 for GNU MPFR 4.0.1

Patches 10 and 11 of GNU MPFR 4.0.1 are available in the bugs section of the MPFR 4.0.1 page.

The main issue is that the `mpfr_erf`

and `mpfr_erfc`

functions can yield an assertion failure due to the fact that the error bound is computed with the `double` type and can overflow. This is fixed by patch 11.

Patches 7 to 9 for GNU MPFR 4.0.1

Patches 7 to 9 of GNU MPFR 4.0.1 are available in the bugs section of the MPFR 4.0.1 page.

The main issue can occur with the formatted output functions (`mpfr_*printf`

) when the `'` flag is used in a locale where the thousands separator is not empty. In some specific cases (that is, when the integer part is rounded upward to 10 or 100), the generated string can be incorrect and since it is shorter than expected, an incorrect buffer size may be provided to the free

function of the current GMP memory allocator. By default, this size is ignored, but it may matter if the memory allocators have been changed with the `mp_set_memory_functions`

GMP function, in which case a possible consequence could be memory corruption.

Patches 1 to 6 for GNU MPFR 4.0.1

Patches 1 to 6 of GNU MPFR 4.0.1 are available in the bugs section of the MPFR 4.0.1 page. The first one fixes a major bug introduced in MPFR 4.0.0 (in a particular case of addition/subtraction), though most applications are probably not affected. The other ones fix minor bugs, with probably no consequences in practice.

For the users of the `Math::MPFR` Perl module, note that patch 6 makes a bug appear in version 4.03 of this module (current version at the time of writing – **[Update 2018-05-08]** A new version of the module is now available).

GNU MPFR 4.0.1 is Released

The GNU MPFR 4.0.1 library (dinde aux marrons, patch level 1) has been released. It fixes some problems of version 4.0.0, which I did not announce here: in particular, a bug in the `mpfr_div_ui`

function, which was present since the introduction of `mpfr_div_ui`

at the very beginning of the development of MPFR in 1999. But as of version 4.0.0, this bug was also affecting the `mpfr_div`

function.

These versions 4.0.* contain many changes compared to versions 3.1.* (GNU MPFR 3.1.0 had been released in October 2011).

GNU MPFR 4.0.0 Release Candidate

The GNU MPFR 4.0.0 release candidate is available.

By the way, I did my first MPFR commit 17 years ago.

Patch 1 for GNU MPFR 3.1.6

Patch 1 of GNU MPFR 3.1.6 is available in the bugs section of the MPFR 3.1.6 page. It fixes the conversion functions `mpfr_get_ld`

, `mpfr_get_si`

, `mpfr_get_ui`

, `mpfr_get_sj`

, `mpfr_get_uj`

and `mpfr_get_z`

when called with a very reduced exponent range.

GNU MPFR 3.1.6 is Released

The GNU MPFR 3.1.6 library (canard à l'orange, patch level 6) has been released. The changes from version 3.1.5:

Improved MPFR manual.

Bug fixes (detailed list on the MPFR 3.1.5 page and

`ChangeLog`file).Autotools: Under Linux, make sure that the old dtags (when supported) are used if the

`LD_LIBRARY_PATH`environment variable is defined; otherwise

would check an installed, compatible MPFR library found in`make check``LD_LIBRARY_PATH`instead of the one that has been built with

.`make`

GNU MPFR 3.1.6 Release Candidate

The GNU MPFR 3.1.6 release candidate has been available for a few days.

Patch 10 for GNU MPFR 3.1.5

Patch 10 of GNU MPFR 3.1.5 is available in the bugs section of the MPFR 3.1.5 page. It fixes incorrect header inclusion introduced by patch 8, in order to get the correct definition of symbols and avoid a link-time error under Microsoft Windows with DLL.

Patch 9 for GNU MPFR 3.1.5

Patch 9 of GNU MPFR 3.1.5 is available in the bugs section of the MPFR 3.1.5 page. It fixes a very important bug for users of platforms with a 32-bit `unsigned long` (32-bit ABI or Microsoft Windows) for very high precisions: computations in `sin_cos.c` suffer from overflows in such precisions (more than about 1,000,000 bits) due to the limited size of the `unsigned long` type. In practice, this introduces an error of up to 2^{−1019574} approximately, so that the trigonometric functions (`mpfr_sin`

, `mpfr_cos`

, `mpfr_tan`

) and functions that call them can be very inaccurate (limiting the overall accuracy to about one million bits for these functions on such platforms).

Patches 3 to 8 for GNU MPFR 3.1.5

Patches 3 to 8 of GNU MPFR 3.1.5 are available in the bugs section of the MPFR 3.1.5 page. The first five fix minor issues and patch 8 fixes some `mpf2mpfr.h` macros (only users of this header file, used to build GMP/mpf programs with MPFR instead of mpf, may be affected).

My Latest Publications

I have two new papers that have just been accepted, both related to GNU MPFR.

Correctly Rounded Arbitrary-Precision Floating-Point Summation, to be published in IEEE Transactions on Computers. DOI: 10.1109/TC.2017.2690632 (official link). PDF file on my personal web site (freely downloadable, © IEEE). Abstract:

We present a fast algorithm together with its low-level implementation of correctly rounded arbitrary-precision floating-point summation. The arithmetic is the one used by the GNU MPFR library: radix 2; no subnormals; each variable (each input and the output) has its own precision. We also give a worst-case complexity of this algorithm and describe how the implementation is tested.

Optimized Binary64 and Binary128 Arithmetic with GNU MPFR, written with Paul Zimmermann. Accepted at the 24th IEEE Symposium on Computer Arithmetic (ARITH 24), which will take place on 24–26 July 2017 in London, England. Abstract:

We describe algorithms used to optimize the GNU MPFR library when the operands fit into one or two words. On modern processors, a correctly rounded addition of two quadruple precision numbers is now performed in 22 cycles, a subtraction in 24 cycles, a multiplication in 32 cycles, a division in 64 cycles, and a square root in 69 cycles. We also introduce a new

*faithful*rounding mode, which enables even faster computations. Those optimizations will be available in version 4 of MPFR.

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