`fft_small_prime_supports_depth`

Synopsis#include <flint/fft_small.h>

int fft_small_prime_supports_depth(ulong n, ulong depth)source

Returns whether a transform of length $2^{\mathtt{depth}}$ can be computed modulo $n$ itself: $2 < n \le 2^{50}$ , $n$ passes fft_small_mulmod_satisfies_bounds, depth is at most 40 and $2^{\max(\mathtt{depth}, 4)} \mid n - 1$ (the context initialisation sd_fft_ctx_init_prime needs $2^4 \mid n - 1$ for every depth). Primality is assumed.

Guides#

Where FLINT uses fft_small

Cite this page

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

@misc{flint-doc-fft-small-fft-small-prime-supports-depth,
  author       = {{The FLINT team}},
  title        = {{fft\_small\_prime\_supports\_depth (fft\_small.h)}},
  howpublished = {FLINT: Fast Library for Number Theory, documentation, version 3.7.0-dev},
  year         = {2026},
  url          = {https://flintlib.org/doc/fft_small/fft_small_prime_supports_depth.html},
  note         = {Generated 2026-11-02}
}

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