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Factor integers using the Elliptic Curve Method

gmp-ecm is a free implementation of the Elliptic Curve Method (ECM) for integer factorization.

The original purpose of the ECMNET project was to make Richard Brent's prediction true, i.e. to find a factor of 50 digits or more by ECM. This goal was attained on September 14, 1998, when Conrad Curry found a 53-digit factor of 2^677-1 c150 using George Woltman's mprime program. The new goal of ECMNET is now to find other large factors by ecm, mainly by contributing to the Cunningham project, most likely the longest, ongoing computational project in history according to Bob Silverman. A new record was set by Nik Lygeros and Michel Mizony, who found in December 1999 a prime factor of 54 digits using GMP-ECM.

See for more information about ecmnet.

Package version:6.3-4


The ECMNET Project

Several number factorization projects could use your help. Since
composite numbers lists can become obsolete quickly, they are not
included in the package but you can have a look at upstream's page to
get you started:

 -- Laurent Fousse <>, Mon, 28 Feb 2005 16:34:07 +0100


This is the README file for GMP-ECM. (See README.lib for the ecm library.)

Table of contents of this file:
1. Basic usage.
2. How to use P-1, P+1, and ECM efficiently?
3. Extra factors and Brent-Suyama's extension.
4. Memory usage.
5. Expression syntax reference for GMP-ECM's syntax parser.
6. Options -save, -resume and -chkpnt.
7. Working with very large numbers (the -prp* options).
8. How to ge


Changes between ecm-6.2.3 and ecm-6.3:
* New assembly code for 64-bit PowerPC (thanks to Philip McLaughlin)
* Allow several processes to write to the same -save file
* More routines in new P+-1 stage 2 use multi-threading in OpenMP build
* Fixed incompatibility with GMP 5.0.0
* Fixed several bugs, and now check return value from malloc() calls
* Fixed linking of GMP which prevented successful buil


ECM(1)                     April 22, 2003                     ECM(1)

       ecm - integer fa


gmp-ecm (6.3-4) unstable; urgency=low

  * Use gcc-4.3 on sparc as 4.4 causes build failure (closes:


r1501 | kruppa | 2010-04-18


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This package was debianized by Laurent Fousse <> on
Tue, 22 Apr 2003 10:19:24 +020

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