summaryrefslogtreecommitdiff
path: root/gsl-1.9/fft/real_pass_n.c
diff options
context:
space:
mode:
Diffstat (limited to 'gsl-1.9/fft/real_pass_n.c')
-rw-r--r--gsl-1.9/fft/real_pass_n.c264
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;
+}