GMP-ECM 6.0

February 28, 2005: We are pleased to announce the release of GMP-ECM 6.0, which may be downloaded from:

This is a major release, with three new developers (Jim Fougeron, Laurent Fousse and Dave Newman), and many improvements with respect to the previous release (5.0.3):

• easier configuration and installation (configure/make);
• new documentation (XML and "man" format);
• new parser for symbolic input, and several new command line options;
• improved code for Fermat numbers, especially in stage 2;
• speed improvement in step 2, especially for large B2;
• Brent-Suyama's extension for P+1;
• computation of the expected number of curves and expected time to find factors of a given number of digits;
• the code is now split between a library (distributed under LGPL), and a frontend (GMP-ECM, distributed under GPL), which makes it possible to call the library functions from another application.

We thank Hartmut Bock, Bruce Dodson, Torbjörn Granlund, Paul Leyland, Japke Rosink who tested preliminary versions, and Allan Steel, Karim Belabas who made useful suggestions concerning the library interface.

Jim Fougeron
Laurent Fousse
Alexander Kruppa
Dave Newman
Paul Zimmermann

Related links:

• the ECMNET factorization project
• the GMP-ECM thread on mersenneforum.org
• ecm is used in the GGNFS number field sieve implementation (project sourceforge page)
• the previous version (5.0.3).
• an official debian package is available.

Known problems:

• some configurations (for example alpha-osf) do not provide the snprintf function [patch].
• the tune and tune2 programs do not link on some systems (e.g. PowerPc G5). [patch].
• the computation of expected curves and time with the -v option may produce a Segmentation fault. [patch].
• the -I n option does not increment B2. [patch].
• Apple computers use \r instead of \n for newline. [patch].
• Some files do not compile under Visual C. [patch].
• Potential bug in stage 2 (with very very small probability, of order 1/N where N is the input number). [patch]. Note: this patch changed on March 9, please apply it again if you got it on March 8.
• The -B2scale option does not work. [patch].