FLINT3.7.0-dev
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fft_small_fft_nmod

Synopsis#include <flint/fft_small.h>
void fft_small_fft_nmod(fft_small_op_t X, const ulong * a, ulong an, ulong itrunc, nmod_t mod, const fft_small_plan_t P)source

Sets X to the forward transform of (a,an)(a, a_n), a polynomial over Z/nZ\mathbb{Z}/n\mathbb{Z} with reduced coefficients, read as zero-padded to length itrunc. Requires itrunc to be a multiple of 8 and at most P->ztrunc; normally itrunc is ana_n rounded up to a multiple of 256, or 2d2^d if the depth dd is less than 8.

If ana_n exceeds itrunc, the polynomial is reduced modulo xitrunc−1x^{\mathtt{itrunc}} - 1, which is meaningful only for cyclic plans with itrunc =2d= 2^d. The primes are transformed in parallel from an≥1500a_n \ge 1500.

Guides#

Cite this page

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