Elliptic Curve Method for Integer Factorization

GMP-ECM reads the numbers to be factored from stdin (one number on each line) and requires a numerical parameter, the stage 1 bound B1. A reasonable stage 2 bound B2 for the given B1 is chosen by default, but can be overridden by a second numerical parameter. By default, GMP-ECM uses the ECM factoring algorithm.

Author: Paul Zimmermann (and many others)