FLINT3.7.0-dev
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_fft_small_np2_choose

Synopsis#include <flint/fft_small.h>
int _fft_small_np2_choose(const mpn_ctx_struct * R, ulong an, ulong bn, ulong len_bound, ulong * bits, ulong * depth)source

Chooses the least depth d∈[8,30]d \in [8, 30] and then the largest chunk size b∈[40,45]b \in [40, 45] with ⌈64an/b⌉+⌈64bn/b⌉−1≤2d\lceil 64 a_n / b \rceil + \lceil 64 b_n / b \rceil - 1 \le 2^d and len_bound ⋅⌈64bn/b⌉⋅22b<p0p1\cdot \lceil 64 b_n / b \rceil \cdot 2^{2b} < p_0 p_1. Returns 0 if there is none.

Cite this page

The FLINT team, “_fft_small_np2_choose (fft_small.h),” FLINT: Fast Library for Number Theory, documentation, version 3.7.0-dev, 2026. https://flintlib.org/doc/fft_small/_fft_small_np2_choose.html (generated 2026-11-02).