Speed up MPC multiplication

[jdemeyer]

Add a patch from Paul Zimmermann which significantly speeds up MPC multiplication (although it is still noticably slower than ComplexField which is based on MPFR).

Timings (time in microseconds for 1 multiplication on an Intel(R) Core(TM) i7-2640M CPU @ 2.80GHz):

Prec (bits)	ComplexField	MPComplexField (old)	MPComplexField (new)
53	0.53	1.09	0.81
128	0.56	1.18	0.90
360	0.77	1.47	1.12
1024	1.74	3.98	3.39

Depends on #15697

CC: @zimmermann6 @jpflori

Component: packages: standard

Author: Jeroen Demeyer

Branch: c86f678

Reviewer: Jean-Pierre Flori

Issue created by migration from https://trac.sagemath.org/ticket/15744

[jdemeyer]

Branch: u/jdemeyer/ticket/15744

[jdemeyer]

Dependencies: #15697

[jdemeyer]

Commit: c86f678

[jdemeyer]

New commits:

00a5937	Upgrade MPC to version 1.0.2
c86f678	Speed up MPC multiplication

[jpflori]

comment:8

For future ref, patch taken from upstream commit r1439 (https://gforge.inria.fr/scm/viewvc.php/trunk/src/mul.c?root=mpc&r1=1298&r2=1439).

[jpflori]

comment:9

Everything looks fine and multiplication is indeed sped up.

[jpflori]

Reviewer: Jean-Pierre Flori

[vbraun]

Changed branch from u/jdemeyer/ticket/15744 to c86f678

[zimmermann6]

comment:11

I have added a new function mpfr_fmma (and its companion mpfr_fmms) in the development version of MPFR. This function is now used in the development version of MPC. Those functions should be faster than the patch used in this ticket. Please could someone update the timings with those new functions?

1. Get the development (svn) version of MPFR.
2. Get the development (git) version of MPC, and check that configure finds mpfr_fmma and it is used in mpc_mul.
3. Rebuild Sage with those version of MPFR and MPC.

Paul

PS: the 1.74ms for ComplexField in 1024 bits looks dubious to me, if you compare to 0.77ms for 360 bits. What is the command used for those timings?

[zimmermann6]

Changed commit from c86f678 to none

[zimmermann6]

comment:12

Jeroen, please could you redo the timings with the new mpfr_fmma from the development version of MPFR (as indicated in comment [comment:11]), and publish the code you used in the description so that we can reproduce your timings?