FLINT3.7.0-dev
/

_nmod_poly_mul_classical, nmod_poly_mul_classical

Synopsis#include <flint/nmod_poly.h>
void _nmod_poly_mul_classical(nn_ptr res, nn_srcptr poly1, slong len1, nn_srcptr poly2, slong len2, nmod_t mod)source
void nmod_poly_mul_classical(nmod_poly_t res, const nmod_poly_t poly1, const nmod_poly_t poly2)source

Set res to the product by the classical algorithm, with O(len1⋅len2)O(\mathit{len1} \cdot \mathit{len2}) operations. The underscore version requires len1≥len2≥1\mathit{len1} \ge \mathit{len2} \ge 1 and does not allow aliasing.

If (n−1)2min⁡(len1,len2)(n-1)^2 \min(\mathit{len1}, \mathit{len2}) fits in one word, the products are accumulated without reduction and every coefficient is reduced once at the end. Otherwise each coefficient is a dot product computed with _nmod_vec_dot_rev, whose method is chosen once for the longest dot product. Squaring uses the symmetry of the product and does about half the multiplications.

Cite this page

The FLINT team, “_nmod_poly_mul_classical, nmod_poly_mul_classical (nmod_poly.h),” FLINT: Fast Library for Number Theory, documentation, version 3.7.0-dev, 2026. https://flintlib.org/doc/nmod_poly/_nmod_poly_mul_classical.html (generated 2026-11-02).