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Diffstat (limited to 'gsl-1.9/fft/hc_main.c')
| -rw-r--r-- | gsl-1.9/fft/hc_main.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/gsl-1.9/fft/hc_main.c b/gsl-1.9/fft/hc_main.c new file mode 100644 index 0000000..591acd4 --- /dev/null +++ b/gsl-1.9/fft/hc_main.c @@ -0,0 +1,188 @@ +/* fft/hc_main.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. + */ + +#include <config.h> +#include <stdlib.h> +#include <math.h> + +#include <gsl/gsl_errno.h> +#include <gsl/gsl_complex.h> +#include <gsl/gsl_fft_halfcomplex.h> + +#include "hc_pass.h" + +int +FUNCTION(gsl_fft_halfcomplex,backward) (BASE data[], const size_t stride, + const size_t n, + const TYPE(gsl_fft_halfcomplex_wavetable) * wavetable, + TYPE(gsl_fft_real_workspace) * work) +{ + int status = FUNCTION(gsl_fft_halfcomplex,transform) (data, stride, n, wavetable, work) ; + return status ; +} + +int +FUNCTION(gsl_fft_halfcomplex,inverse) (BASE data[], const size_t stride, + const size_t n, + const TYPE(gsl_fft_halfcomplex_wavetable) * wavetable, + TYPE(gsl_fft_real_workspace) * work) +{ + int status = FUNCTION(gsl_fft_halfcomplex,transform) (data, stride, n, wavetable, work); + + if (status) + { + return status; + } + + /* normalize inverse fft with 1/n */ + + { + const double norm = 1.0 / n; + size_t i; + for (i = 0; i < n; i++) + { + data[stride*i] *= norm; + } + } + return status; +} + +int +FUNCTION(gsl_fft_halfcomplex,transform) (BASE data[], const size_t stride, const size_t n, + const TYPE(gsl_fft_halfcomplex_wavetable) * wavetable, + TYPE(gsl_fft_real_workspace) * work) +{ + BASE * const scratch = work->scratch; + + BASE * in; + BASE * out; + size_t istride, ostride ; + + + size_t factor, product, q; + size_t i; + size_t nf; + int state; + int product_1; + int tskip; + TYPE(gsl_complex) *twiddle1, *twiddle2, *twiddle3, *twiddle4; + + if (n == 0) + { + GSL_ERROR ("length n must be positive integer", GSL_EDOM); + } + + if (n == 1) + { /* FFT of one data point is the identity */ + return 0; + } + + if (n != wavetable->n) + { + GSL_ERROR ("wavetable does not match length of data", GSL_EINVAL); + } + + if (n != work->n) + { + GSL_ERROR ("workspace does not match length of data", GSL_EINVAL); + } + + nf = wavetable->nf; + product = 1; + state = 0; + + for (i = 0; i < nf; i++) + { + factor = wavetable->factor[i]; + product_1 = product; + product *= factor; + q = n / product; + + tskip = (q + 1) / 2 - 1; + + if (state == 0) + { + in = data; + istride = stride; + out = scratch; + ostride = 1; + state = 1; + } + else + { + in = scratch; + istride = 1; + out = data; + ostride = stride; + state = 0; + } + + if (factor == 2) + { + twiddle1 = wavetable->twiddle[i]; + FUNCTION(fft_halfcomplex,pass_2) (in, istride, out, ostride, + product, n, twiddle1); + } + else if (factor == 3) + { + twiddle1 = wavetable->twiddle[i]; + twiddle2 = twiddle1 + tskip; + FUNCTION(fft_halfcomplex,pass_3) (in, istride, out, ostride, + product, n, twiddle1, twiddle2); + } + else if (factor == 4) + { + twiddle1 = wavetable->twiddle[i]; + twiddle2 = twiddle1 + tskip; + twiddle3 = twiddle2 + tskip; + FUNCTION(fft_halfcomplex,pass_4) (in, istride, out, ostride, + product, n, twiddle1, twiddle2, + twiddle3); + } + else if (factor == 5) + { + twiddle1 = wavetable->twiddle[i]; + twiddle2 = twiddle1 + tskip; + twiddle3 = twiddle2 + tskip; + twiddle4 = twiddle3 + tskip; + FUNCTION(fft_halfcomplex,pass_5) (in, istride, out, ostride, + product, n, twiddle1, twiddle2, + twiddle3, twiddle4); + } + else + { + twiddle1 = wavetable->twiddle[i]; + FUNCTION(fft_halfcomplex,pass_n) (in, istride, out, ostride, + factor, product, n, twiddle1); + } + } + + if (state == 1) /* copy results back from scratch to data */ + { + for (i = 0; i < n; i++) + { + data[stride*i] = scratch[i] ; + } + } + + return 0; + +} + + |