fftw_low.c

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/*
 Copyright (C) 2002 M. Marques, A. Castro, A. Rubio, G. Bertsch
 
 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2, or (at your option)
 any later version.
 
 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU General Public License for more details.
 
 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 02110-1301, USA.
 
*/
 
#include <config.h>
#include <fortran_types.h>
 
void fft_optimize(int *n, int par) {
  if (*n <= 2)
    return;
 
  for (;; (*n)++) {
    int i, n2;
 
    if ((par >= 0) && (*n % 2 != par))
      continue;
 
    /* For debugging:                 */
    /* printf("%i has factors ", *n); */
 
    n2 = *n;
    for (i = 2; i <= n2; i++) {
      if (n2 % i == 0) {
        /* For debugging:    */
  /* printf("%i ", i); */
  if(i > 7) break;
  n2 = n2 / i;
  i--;
      }
    }
    /* For debugging: */
    /* printf("\n");  */
    if (n2 == 1)
      return;
  }
}
 
void FC_FUNC_(oct_fft_optimize, OCT_FFT_OPTIMIZE)(fint *n, fint *par) {
  fft_optimize(n, *par);
}