diff options
Diffstat (limited to 'gsl-1.9/fft/c_pass_5.c')
| -rw-r--r-- | gsl-1.9/fft/c_pass_5.c | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/gsl-1.9/fft/c_pass_5.c b/gsl-1.9/fft/c_pass_5.c new file mode 100644 index 0000000..d8a9d65 --- /dev/null +++ b/gsl-1.9/fft/c_pass_5.c @@ -0,0 +1,205 @@ +/* fft/c_pass_5.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 int +FUNCTION(fft_complex,pass_5) (const BASE in[], + const size_t istride, + BASE out[], + const size_t ostride, + const gsl_fft_direction sign, + const size_t product, + const size_t n, + const TYPE(gsl_complex) twiddle1[], + const TYPE(gsl_complex) twiddle2[], + const TYPE(gsl_complex) twiddle3[], + const TYPE(gsl_complex) twiddle4[]) +{ + size_t i = 0, j = 0; + size_t k, k1; + + const size_t factor = 5; + const size_t m = n / factor; + const size_t q = n / product; + const size_t p_1 = product / factor; + const size_t jump = (factor - 1) * p_1; + + const ATOMIC sin_2pi_by_5 = sin (2.0 * M_PI / 5.0); + const ATOMIC sin_2pi_by_10 = sin (2.0 * M_PI / 10.0); + + for (k = 0; k < q; k++) + { + + ATOMIC w1_real, w1_imag, w2_real, w2_imag, w3_real, w3_imag, w4_real, + w4_imag; + + if (k == 0) + { + w1_real = 1.0; + w1_imag = 0.0; + w2_real = 1.0; + w2_imag = 0.0; + w3_real = 1.0; + w3_imag = 0.0; + w4_real = 1.0; + w4_imag = 0.0; + } + else + { + if (sign == gsl_fft_forward) + { + /* forward tranform */ + w1_real = GSL_REAL(twiddle1[k - 1]); + w1_imag = GSL_IMAG(twiddle1[k - 1]); + w2_real = GSL_REAL(twiddle2[k - 1]); + w2_imag = GSL_IMAG(twiddle2[k - 1]); + w3_real = GSL_REAL(twiddle3[k - 1]); + w3_imag = GSL_IMAG(twiddle3[k - 1]); + w4_real = GSL_REAL(twiddle4[k - 1]); + w4_imag = GSL_IMAG(twiddle4[k - 1]); + } + else + { + /* backward tranform: w -> conjugate(w) */ + w1_real = GSL_REAL(twiddle1[k - 1]); + w1_imag = -GSL_IMAG(twiddle1[k - 1]); + w2_real = GSL_REAL(twiddle2[k - 1]); + w2_imag = -GSL_IMAG(twiddle2[k - 1]); + w3_real = GSL_REAL(twiddle3[k - 1]); + w3_imag = -GSL_IMAG(twiddle3[k - 1]); + w4_real = GSL_REAL(twiddle4[k - 1]); + w4_imag = -GSL_IMAG(twiddle4[k - 1]); + } + } + + for (k1 = 0; k1 < p_1; k1++) + { + + ATOMIC x0_real, x0_imag, x1_real, x1_imag, x2_real, x2_imag, + x3_real, x3_imag, x4_real, x4_imag; + + const ATOMIC z0_real = REAL(in,istride,i); + const ATOMIC z0_imag = IMAG(in,istride,i); + const ATOMIC z1_real = REAL(in,istride,i + m); + const ATOMIC z1_imag = IMAG(in,istride,i + m); + const ATOMIC z2_real = REAL(in,istride,i + 2*m); + const ATOMIC z2_imag = IMAG(in,istride,i + 2*m); + const ATOMIC z3_real = REAL(in,istride,i + 3*m); + const ATOMIC z3_imag = IMAG(in,istride,i + 3*m); + const ATOMIC z4_real = REAL(in,istride,i + 4*m); + const ATOMIC z4_imag = IMAG(in,istride,i + 4*m); + + /* compute x = W(5) z */ + + /* t1 = z1 + z4 */ + const ATOMIC t1_real = z1_real + z4_real; + const ATOMIC t1_imag = z1_imag + z4_imag; + + /* t2 = z2 + z3 */ + const ATOMIC t2_real = z2_real + z3_real; + const ATOMIC t2_imag = z2_imag + z3_imag; + + /* t3 = z1 - z4 */ + const ATOMIC t3_real = z1_real - z4_real; + const ATOMIC t3_imag = z1_imag - z4_imag; + + /* t4 = z2 - z3 */ + const ATOMIC t4_real = z2_real - z3_real; + const ATOMIC t4_imag = z2_imag - z3_imag; + + /* t5 = t1 + t2 */ + const ATOMIC t5_real = t1_real + t2_real; + const ATOMIC t5_imag = t1_imag + t2_imag; + + /* t6 = (sqrt(5)/4)(t1 - t2) */ + const ATOMIC t6_real = (sqrt (5.0) / 4.0) * (t1_real - t2_real); + const ATOMIC t6_imag = (sqrt (5.0) / 4.0) * (t1_imag - t2_imag); + + /* t7 = z0 - ((t5)/4) */ + const ATOMIC t7_real = z0_real - t5_real / 4.0; + const ATOMIC t7_imag = z0_imag - t5_imag / 4.0; + + /* t8 = t7 + t6 */ + const ATOMIC t8_real = t7_real + t6_real; + const ATOMIC t8_imag = t7_imag + t6_imag; + + /* t9 = t7 - t6 */ + const ATOMIC t9_real = t7_real - t6_real; + const ATOMIC t9_imag = t7_imag - t6_imag; + + /* t10 = sin(2 pi/5) t3 + sin(2 pi/10) t4 */ + const ATOMIC t10_real = ((int) sign) * (sin_2pi_by_5 * t3_real + + sin_2pi_by_10 * t4_real); + const ATOMIC t10_imag = ((int) sign) * (sin_2pi_by_5 * t3_imag + + sin_2pi_by_10 * t4_imag); + + /* t11 = sin(2 pi/10) t3 - sin(2 pi/5) t4 */ + const ATOMIC t11_real = ((int) sign) * (sin_2pi_by_10 * t3_real - + sin_2pi_by_5 * t4_real); + const ATOMIC t11_imag = ((int) sign) * (sin_2pi_by_10 * t3_imag - + sin_2pi_by_5 * t4_imag); + + /* x0 = z0 + t5 */ + x0_real = z0_real + t5_real; + x0_imag = z0_imag + t5_imag; + + /* x1 = t8 + i t10 */ + x1_real = t8_real - t10_imag; + x1_imag = t8_imag + t10_real; + + /* x2 = t9 + i t11 */ + x2_real = t9_real - t11_imag; + x2_imag = t9_imag + t11_real; + + /* x3 = t9 - i t11 */ + x3_real = t9_real + t11_imag; + x3_imag = t9_imag - t11_real; + + /* x4 = t8 - i t10 */ + x4_real = t8_real + t10_imag; + x4_imag = t8_imag - t10_real; + + /* apply twiddle factors */ + + /* to0 = 1 * x0 */ + REAL(out,ostride,j) = x0_real; + IMAG(out,ostride,j) = x0_imag; + + /* to1 = w1 * x1 */ + REAL(out,ostride,j + p_1) = w1_real * x1_real - w1_imag * x1_imag; + IMAG(out,ostride,j + p_1) = w1_real * x1_imag + w1_imag * x1_real; + + /* to2 = w2 * x2 */ + REAL(out,ostride,j + 2*p_1) = w2_real * x2_real - w2_imag * x2_imag; + IMAG(out,ostride,j+2*p_1) = w2_real * x2_imag + w2_imag * x2_real; + + /* to3 = w3 * x3 */ + REAL(out,ostride,j+3*p_1) = w3_real * x3_real - w3_imag * x3_imag; + IMAG(out,ostride,j+3*p_1) = w3_real * x3_imag + w3_imag * x3_real; + + /* to4 = w4 * x4 */ + REAL(out,ostride,j+4*p_1) = w4_real * x4_real - w4_imag * x4_imag; + IMAG(out,ostride,j+4*p_1) = w4_real * x4_imag + w4_imag * x4_real; + + i++; + j++; + } + j += jump; + } + return 0; +} |