Third MPFR-MPC Developers Meeting

Location: LORIA, Nancy [directions]

The goal of this meeting is to discuss future developments of the GNU MPFR and the GNU MPC libraries, following the previous meetings from 2011 in Paris and from 2012 in Bordeaux. It is open to all people who are interested to contribute to GNU MPFR and/or GNU MPC, either in writing new code or contributing new ideas (see How to contribute to GNU MPFR?).

Practical organization: there is no registration fee, however people interested in attending this meeting are kindly requested to inform Paul Zimmermann. We have partial support from GDR-IM for two PhD students, other participants are supposed to take in charge their travel and accomodation expenses.

Proposed topics:

• [MPFR/MPC] improve test coverage: 96.4% for MPFR on 2014-01-12, 99.7% for MPC on 2014-01-10.

  Improved to 100% for MPC.

• [MPFR/MPC] MPFR/MPCbench program (like GMPbench)

  Mickaël Gastineau and Bill Hart did design a MPCbench program, which was adapted and integrated into MPFR.

• [MPFR/MPC] extend mpcheck to find bugs in glibc for float, double and long double, in any rounding mode (large errors, spurious or missing exceptions, see msg00132.html).

  See progress on this page.

• [MPFR] use MPFR in GCC for compile-time decimal to binary conversion (bug 21718)

  Already done by Joseph Myers before the workshop.

• [MPFR] improve the test of mpfr_sum (see https://sympa.inria.fr/sympa/arc/mpfr/2013-10/msg00016.html)

  Started by Vincent Lefèvre.

• [MPFR] status of Annex F support (see https://sympa.inria.fr/sympa/arc/mpfr/2013-12/msg00001.html)

  It remained only to fix mpfr_lngamma, done by Vincent Lefèvre.

• [MPFR] Implement scaled erfc, as previously requested for GNU Fortran (suggested by Joseph Myers, see msg00054.html)

  Started by Fredrik Johansson.

• [MPFR] Implement missing functions from clause 9 of IEEE 754-2008 (sinpi, atanpi, atan2pi, ...). C bindings for these functions will appear in draft TS 18661-4 (suggested by Joseph Myers).
• [MPFR] memory usage of the mpfr_t type (Andreas).

  Discussed, it seems we cannot decrease it simply.

• [MPFR] add eint1 (Andreas)
• [MPFR] hot/cold function attribute (Patrick, done)
• [MPFR] implement a new function to compute a*b+c*d (suggested by Jeroen Demeyer)

  It appeared we first want to optimize mpfr_fma, started by Paul Zimmermann, while Jeroen Demeyer works on mpfr_add. An improved code for a*b+c*d was put in the MPC svn.

• [MPFR] implement a dot product function (suggested by Philippe Théveny)
• [MPFR] check time regression for low precisions (Patrick, done)
• [MPFR] adapt make check for automake 1.13 and later (Vincent, done)
• [MPFR] prototype for shared cache (done by Patrick, to be reviewed by Mickaël and Fredrik before including in the trunk)
• [MPFR] optimize mpfr_exp (Patrick, done)
• [MPFR] improve mpfr_const_euler

  Done by Fredrik, integrated in the development version.

• [MPC] new release? (see http://lists.gforge.inria.fr/pipermail/mpc-discuss/2013-December/001265.html)

  A new release 1.0.2 was made before the workshop, see here.

• [MPC] new testing framework (Théveny, Gastineau)

  Done and merged during the workshop.

• [MPC] scripts and web page comparing timings with different systems

  Put by Philippe Théveny in revisions 1432 to 1435 of MPC.

• [MPC] have FAST_COMPUTE_IF_SMALL_INPUT macros for MPC? (see http://lists.gforge.inria.fr/pipermail/mpc-discuss/2013-December/001266.html)
• [MPC] Speeding up the MPC complex inverse trig and hyperbolic functions in the slow cases (see 001196.html, 001270.html and msg00809.html) [asin(1+i*y) solved by r1402]
• [MPC] Implement various complex functions C99/C11 reserve for possible future addition (see 001090.html, suggested by Joseph Myers)
.
• [MPC] complex AGM

  Started by Andreas Enge

• [MPC] roots of unity
• [MPC] add LogGamma, Zeta, ... (Andreas)
• [MPC] faithful rounding for mpc_mul (suggested by Andreas)
• potential applications for interval arithmetic and the P1788 working group: cf talk of Nathalie Revol, that will be presented at the ICVRAM 2014 conference, see this paper
• complex ball arithmetic (suggested by Andreas)
• interface with Arb: cf talk of Fredrik Johansson

Tentative schedule: The official meeting will start on January 20 noon, and end on January 22 noon. More details will be announced later

January 21st, 8PM: workshop dinner offered by GDR IM and Caramel.

Support for PhD students: partial support was obtained by GDR-IM for two PhD students, please contact Paul Zimmermann before November 20, 2013.

Confirmed participants:
Jeroen Demeyer
Andreas Enge
Mickaël Gastineau
Bill Hart
Fredrik Johansson
Vincent Lefèvre
Patrick Pélissier
Nathalie Revol
Philippe Théveny
Paul Zimmermann
Sponsors: and ERC ANTICS