| /* fft/hc_init.c |
| * |
| * Copyright (C) 1996, 1997, 1998, 1999, 2000 Brian Gough |
| * |
| * 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 of the License, 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. |
| */ |
| |
| TYPE(gsl_fft_halfcomplex_wavetable) * |
| FUNCTION(gsl_fft_halfcomplex_wavetable,alloc) (size_t n) |
| { |
| int status; |
| size_t i; |
| size_t n_factors; |
| size_t t, product, product_1, q; |
| double d_theta; |
| |
| TYPE(gsl_fft_halfcomplex_wavetable) * wavetable ; |
| |
| if (n == 0) |
| { |
| GSL_ERROR_VAL ("length n must be positive integer", GSL_EDOM, 0); |
| } |
| |
| wavetable = (TYPE(gsl_fft_halfcomplex_wavetable) *) |
| malloc(sizeof(TYPE(gsl_fft_halfcomplex_wavetable))); |
| |
| if (wavetable == NULL) |
| { |
| GSL_ERROR_VAL ("failed to allocate struct", GSL_ENOMEM, 0); |
| } |
| |
| wavetable->trig = (TYPE(gsl_complex) *) malloc (n * sizeof (TYPE(gsl_complex))); |
| |
| if (wavetable->trig == NULL) |
| { |
| /* error in constructor, prevent memory leak */ |
| |
| free(wavetable) ; |
| |
| GSL_ERROR_VAL ("failed to allocate trigonometric lookup table", |
| GSL_ENOMEM, 0); |
| } |
| |
| wavetable->n = n ; |
| |
| status = fft_halfcomplex_factorize (n, &n_factors, wavetable->factor); |
| |
| if (status) |
| { |
| /* error in constructor, prevent memory leak */ |
| |
| free(wavetable->trig) ; |
| free(wavetable) ; |
| |
| GSL_ERROR_VAL ("factorization failed", GSL_EFACTOR, 0); |
| } |
| |
| wavetable->nf = n_factors; |
| |
| d_theta = 2.0 * M_PI / ((double) n); |
| |
| t = 0; |
| product = 1; |
| for (i = 0; i < n_factors; i++) |
| { |
| size_t j; |
| const size_t factor = wavetable->factor[i]; |
| wavetable->twiddle[i] = wavetable->trig + t; |
| product_1 = product; /* product_1 = p_(i-1) */ |
| product *= factor; |
| q = n / product; |
| |
| for (j = 1; j < factor; j++) |
| { |
| size_t k; |
| size_t m = 0; |
| for (k = 1; k < (q + 1) / 2; k++) |
| { |
| double theta; |
| m = m + j * product_1; |
| m = m % n; |
| theta = d_theta * m; /* d_theta*j*k*product_1 */ |
| GSL_REAL(wavetable->trig[t]) = cos (theta); |
| GSL_IMAG(wavetable->trig[t]) = sin (theta); |
| |
| t++; |
| } |
| } |
| } |
| |
| if (t > (n / 2)) |
| { |
| /* error in constructor, prevent memory leak */ |
| |
| free(wavetable->trig) ; |
| free(wavetable) ; |
| |
| GSL_ERROR_VAL ("overflowed trigonometric lookup table", GSL_ESANITY, 0); |
| } |
| |
| return wavetable; |
| } |
| |
| |
| void |
| FUNCTION(gsl_fft_halfcomplex_wavetable,free) (TYPE(gsl_fft_halfcomplex_wavetable) * wavetable) |
| { |
| |
| /* release trigonometric lookup tables */ |
| |
| free (wavetable->trig); |
| wavetable->trig = NULL; |
| |
| free (wavetable); |
| } |
| |