Section: Software

GNU MPFR

Participant : Paul Zimmermann [contact] .

GNU MPFR is one of the main pieces of software developed by the Caramel team. Since end 2006, with the departure of Vincent Lefèvre to Ens Lyon, it has become a joint project between Caramel and the Arénaire project-team (Inria Grenoble - Rhône-Alpes). GNU MPFR is a library for computing with arbitrary precision floating-point numbers, together with well-defined semantics, and is distributed under the Lgpl license. All arithmetic operations are performed according to a rounding mode provided by the user, and all results are guaranteed correct to the last bit, according to the given rounding mode.

Several software systems use GNU MPFR , for example: the Gcc and Gfortran compilers; the Sage computer algebra system; the Kde calculator Abakus by Michael Pyne; cgal (Computational Geometry Algorithms Library) developed by the Geometrica project-team (Inria Sophia Antipolis - Méditerranée); Gappa, by Guillaume Melquiond; Sollya, by Sylvain Chevillard, Mioara Joldeş and Christoph Lauter; Genius Math Tool and the Gel language, by Jiri Lebl; Giac/Xcas, a free computer algebra system, by Bernard Parisse; the iRRAM exact arithmetic implementation from Norbert Müller (University of Trier, Germany); the Magma computational algebra system; and the Wcalc calculator by Kyle Wheeler.

The main developments in 2011 are the release of version 3.0.1 in April, and the release of version 3.1.0 (the “canard à l'orange” release) in October. The main changes in GNU MPFR 3.1.0 are the following: thread local storage (TLS) support is now detected automatically, the squaring and division routines got a major speed up thanks to Mulders' algorithm [20] , and a new divide-by-zero exception was introduced. Note that the automatic TLS support did exhibit several compiler bugs (http://www.loria.fr/~zimmerma/software/compilerbugs.html ). We had a developers meeting in January 13-14, and in August GNU MPFR was presented at the GNU Hackers Meeting in Paris.