diff options
Diffstat (limited to 'gsl-1.9/fft/real_pass_n.c')
-rw-r--r-- | gsl-1.9/fft/real_pass_n.c | 264 |
1 files changed, 264 insertions, 0 deletions
diff --git a/gsl-1.9/fft/real_pass_n.c b/gsl-1.9/fft/real_pass_n.c new file mode 100644 index 0000000..984728c --- /dev/null +++ b/gsl-1.9/fft/real_pass_n.c @@ -0,0 +1,264 @@ +/* fft/real_pass_n.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. + */ + +static void +FUNCTION(fft_real,pass_n) (const BASE in[], + const size_t istride, + BASE out[], + const size_t ostride, + const size_t factor, + const size_t product, + const size_t n, + const TYPE(gsl_complex) twiddle[]) +{ + size_t k, k1; + + const size_t m = n / factor; + const size_t q = n / product; + const size_t product_1 = product / factor; + + size_t e1, e2; + + const double d_theta = 2.0 * M_PI / ((double) factor); + const ATOMIC cos_d_theta = cos (d_theta); + const ATOMIC sin_d_theta = sin (d_theta); + + for (k1 = 0; k1 < q; k1++) + { + /* compute x = W(factor) z, for z real */ + + ATOMIC dw_real = 1.0, dw_imag = 0.0; + + for (e1 = 0; e1 <= factor - e1; e1++) + { + ATOMIC sum_real = 0.0; + ATOMIC sum_imag = 0.0; + + ATOMIC w_real = 1.0, w_imag = 0.0; + + if (e1 > 0) + { + ATOMIC tmp_real = dw_real * cos_d_theta + dw_imag * sin_d_theta; + ATOMIC tmp_imag = -dw_real * sin_d_theta + dw_imag * cos_d_theta; + dw_real = tmp_real; + dw_imag = tmp_imag; + } + + for (e2 = 0; e2 < factor; e2++) + { + ATOMIC z_real = VECTOR(in,istride,k1 * product_1 + e2 * m); + + if (e2 > 0) + { + ATOMIC tmp_real = dw_real * w_real - dw_imag * w_imag; + ATOMIC tmp_imag = dw_real * w_imag + dw_imag * w_real; + w_real = tmp_real; + w_imag = tmp_imag; + } + + sum_real += w_real * z_real; + sum_imag += w_imag * z_real; + + } + if (e1 == 0) + { + const size_t to0 = product * k1; + VECTOR(out,ostride,to0) = sum_real; + } + else if (e1 < factor - e1) + { + const size_t to0 = k1 * product + 2 * e1 * product_1 - 1; + VECTOR(out,ostride,to0) = sum_real; + VECTOR(out,ostride,to0 + 1) = sum_imag; + } + else if (e1 == factor - e1) + { + const size_t to0 = k1 * product + 2 * e1 * product_1 - 1; + VECTOR(out,ostride,to0) = sum_real; + } + + } + } + + if (product_1 == 1) + return; + + for (k = 1; k < (product_1 + 1) / 2; k++) + { + for (k1 = 0; k1 < q; k1++) + { + + ATOMIC dw_real = 1.0, dw_imag = 0.0; + + for (e1 = 0; e1 < factor; e1++) + { + ATOMIC sum_real = 0.0, sum_imag = 0.0; + + ATOMIC w_real = 1.0, w_imag = 0.0; + + if (e1 > 0) + { + const ATOMIC tmp_real = dw_real * cos_d_theta + dw_imag * sin_d_theta; + const ATOMIC tmp_imag = -dw_real * sin_d_theta + dw_imag * cos_d_theta; + dw_real = tmp_real; + dw_imag = tmp_imag; + } + + for (e2 = 0; e2 < factor; e2++) + { + + int tskip = (product_1 + 1) / 2 - 1; + const size_t from0 = k1 * product_1 + 2 * k + e2 * m - 1; + ATOMIC tw_real, tw_imag; + ATOMIC z_real, z_imag; + + if (e2 == 0) + { + tw_real = 1.0; + tw_imag = 0.0; + } + else + { + const size_t t_index = (k - 1) + (e2 - 1) * tskip; + tw_real = GSL_REAL(twiddle[t_index]); + tw_imag = -GSL_IMAG(twiddle[t_index]); + } + + { + const ATOMIC f0_real = VECTOR(in,istride,from0); + const ATOMIC f0_imag = VECTOR(in,istride,from0 + 1); + + z_real = tw_real * f0_real - tw_imag * f0_imag; + z_imag = tw_real * f0_imag + tw_imag * f0_real; + } + + if (e2 > 0) + { + const ATOMIC tmp_real = dw_real * w_real - dw_imag * w_imag; + const ATOMIC tmp_imag = dw_real * w_imag + dw_imag * w_real; + w_real = tmp_real; + w_imag = tmp_imag; + } + + sum_real += w_real * z_real - w_imag * z_imag; + sum_imag += w_real * z_imag + w_imag * z_real; + } + + if (e1 < factor - e1) + { + const size_t to0 = k1 * product - 1 + 2 * e1 * product_1 + 2 * k; + VECTOR(out,ostride,to0) = sum_real; + VECTOR(out,ostride,to0 + 1) = sum_imag; + } + else + { + const size_t to0 = k1 * product - 1 + 2 * (factor - e1) * product_1 - 2 * k; + VECTOR(out,ostride,to0) = sum_real; + VECTOR(out,ostride,to0 + 1) = -sum_imag; + } + + } + } + } + + + if (product_1 % 2 == 1) + return; + + { + double tw_arg = M_PI / ((double) factor); + ATOMIC cos_tw_arg = cos (tw_arg); + ATOMIC sin_tw_arg = -sin (tw_arg); + + for (k1 = 0; k1 < q; k1++) + { + ATOMIC dw_real = 1.0, dw_imag = 0.0; + + for (e1 = 0; e1 < factor; e1++) + { + ATOMIC z_real, z_imag; + + ATOMIC sum_real = 0.0; + ATOMIC sum_imag = 0.0; + + ATOMIC w_real = 1.0, w_imag = 0.0; + ATOMIC tw_real = 1.0, tw_imag = 0.0; + + if (e1 > 0) + { + ATOMIC t_real = dw_real * cos_d_theta + dw_imag * sin_d_theta; + ATOMIC t_imag = -dw_real * sin_d_theta + dw_imag * cos_d_theta; + dw_real = t_real; + dw_imag = t_imag; + } + + for (e2 = 0; e2 < factor; e2++) + { + + if (e2 > 0) + { + ATOMIC tmp_real = tw_real * cos_tw_arg - tw_imag * sin_tw_arg; + ATOMIC tmp_imag = tw_real * sin_tw_arg + tw_imag * cos_tw_arg; + tw_real = tmp_real; + tw_imag = tmp_imag; + } + + if (e2 > 0) + { + ATOMIC tmp_real = dw_real * w_real - dw_imag * w_imag; + ATOMIC tmp_imag = dw_real * w_imag + dw_imag * w_real; + w_real = tmp_real; + w_imag = tmp_imag; + } + + + { + const size_t from0 = k1 * product_1 + 2 * k + e2 * m - 1; + const ATOMIC f0_real = VECTOR(in,istride,from0); + z_real = tw_real * f0_real; + z_imag = tw_imag * f0_real; + } + + sum_real += w_real * z_real - w_imag * z_imag; + sum_imag += w_real * z_imag + w_imag * z_real; + } + + if (e1 + 1 < factor - e1) + { + const size_t to0 = k1 * product - 1 + 2 * e1 * product_1 + 2 * k; + VECTOR(out,ostride,to0) = sum_real; + VECTOR(out,ostride,to0 + 1) = sum_imag; + } + else if (e1 + 1 == factor - e1) + { + const size_t to0 = k1 * product - 1 + 2 * e1 * product_1 + 2 * k; + VECTOR(out,ostride,to0) = sum_real; + } + else + { + const size_t to0 = k1 * product - 1 + 2 * (factor - e1) * product_1 - 2 * k; + VECTOR(out,ostride,to0) = sum_real; + VECTOR(out,ostride,to0 + 1) = -sum_imag; + } + + } + } + } + return; +} |