Msieve can factor large integers. It is a library doing the factoring work and a small program making use of the library. Trial division and Pollard Rho is used on all inputs; if the result is less than 25 digits in size, tiny custom routines do the factoring. For larger numbers, the code switches to the GMP-ECM library and runs the P-1, P+1 and ECM algorithms, expending a user-configurable amount of effort to do so. If these do not completely factor the input number, the library switches to the heavy artillery. Unless told otherwise, Msieve runs the self-initializing quadratic sieve algorithm, and if this doesn't factor the input number then you've found a library problem.

The maximum size of numbers that can be given to the library is hardwired at compile time. Currently the code can handle numbers up to ~310 digits.

Author: Jason Papadopoulos