n_ll_factor_ecm
Synopsis
#include <flint/ulong_extras.h>int n_ll_factor_ecm(nn_ptr factor, ulong nhi, ulong nlo, ulong curves, ulong B1, ulong B2, flint_rand_t state)sourceThe elliptic curve method for an odd two-limb n with n_{hi} \ne 0, trying up to curves curves with bounds B_1, B_2 (if B_2 < B_1, then 100 B_1 is used). Returns 1 and writes a factor on success, otherwise 0.
Curves use Suyama's parametrisation. Both stages run in two-limb Montgomery arithmetic, roughly twice as fast as fmpz_factor_ecm with the same parameters for n of this size.
Cite this page
The FLINT team, “n_ll_factor_ecm (ulong_extras.h),” FLINT: Fast Library for Number Theory, documentation, version 3.7.0-dev, 2026. https://flintlib.org/doc/ulong_extras/n_ll_factor_ecm.html (generated 2026-10-20).
@misc{flint-doc-ulong-extras-n-ll-factor-ecm,
author = {{The FLINT team}},
title = {{n\_ll\_factor\_ecm (ulong\_extras.h)}},
howpublished = {FLINT: Fast Library for Number Theory, documentation, version 3.7.0-dev},
year = {2026},
url = {https://flintlib.org/doc/ulong_extras/n_ll_factor_ecm.html},
note = {Generated 2026-10-20}
}