Question for the HP guys....

[Mark Hardman]

(10-09-2017 12:03 AM)Tim Wessman Wrote:  Download the source, search for "fft" and you'll probably find it. Bernard might chime in.

https://www-fourier.ujf-grenoble.fr/~par...modpoly.cc

Around line 3171:

Code:

  // Fast Fourier Transform, f the poly sum_{j<n} f_j x^j, 
  // and w=[1,omega,...,omega^[m-1]] with m a multiple of n (m=step*n)
  // return [f(1),f(omega),...,f(omega^[n-1]) [it's indeed n, not m]
  // WARNING f is given in ascending power
  void fft(const modpoly & f,const modpoly & w ,modpoly & res,environment * env){