/* $Id$ */ /* * Copyright (c) 2010 Dimitri Sokolyuk * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ #include #include #include #include struct fft { fftw_plan plan; double *in; double *out; int n; }; struct fft * init_fft(int n) { struct fft *p; p = malloc(sizeof(struct fft)); p->in = fftw_malloc(n * sizeof(double)); p->out = fftw_malloc(n * sizeof(double)); p->plan = fftw_plan_r2r_1d(n, p->in, p->out, FFTW_R2HC, FFTW_MEASURE); p->n = n; return p; } int dofft(struct fft *p, double *data) { int i, n; memset(p->out, 0, p->n * sizeof(double)); memcpy(p->in, data, p->n * sizeof(double)); fftw_execute(p->plan); n = p->n / 2; for (i = 1; i < n; i++) data[i - 1] = sqrt(i * (p->out[i] * p->out[i] + p->out[p->n - i] * p->out[p->n - i])); return 0; }