File indexing completed on 2024-05-12 03:47:50

 /*
     File                 : nsl_corr.c
     Project              : LabPlot
     Description          : NSL discrete correlation functions
     --------------------------------------------------------------------
     SPDX-FileCopyrightText: 2018 Stefan Gerlach <stefan.gerlach@uni.kn>
     SPDX-License-Identifier: GPL-2.0-or-later
 */
 
 #include "nsl_corr.h"
 #include "nsl_common.h"
 #include <gsl/gsl_cblas.h>
 #include <gsl/gsl_fft_halfcomplex.h>
 #ifdef HAVE_FFTW3
 #include <fftw3.h>
 #endif
 
 const char* nsl_corr_type_name[] = {i18n("Linear (Zero-padded)"), i18n("Circular")};
 const char* nsl_corr_norm_name[] = {i18n("None"), i18n("Biased"), i18n("Unbiased"), i18n("Coeff")};
 
 int nsl_corr_correlation(double s[], size_t n, double r[], size_t m, nsl_corr_type_type type, nsl_corr_norm_type normalize, double out[]) {
     return nsl_corr_fft_type(s, n, r, m, type, normalize, out);
 }
 
 int nsl_corr_fft_type(double s[], size_t n, double r[], size_t m, nsl_corr_type_type type, nsl_corr_norm_type normalize, double out[]) {
     size_t i, size, N = GSL_MAX(n, m), maxlag = N - 1;
     if (type == nsl_corr_type_linear)
         size = maxlag + N;
     else // circular
         size = N;
 
     size_t oldsize = size;
 #ifdef HAVE_FFTW3
     // already zero-pad here for FFT method and FFTW r2c
     size = 2 * (size / 2 + 1);
 #endif
 
     // zero-padded arrays
     double* stmp = (double*)malloc(size * sizeof(double));
     if (stmp == NULL) {
         printf("nsl_corr_fft_type(): ERROR allocating memory for 'stmp'!\n");
         return -1;
     }
 
     double* rtmp = (double*)malloc(size * sizeof(double));
     if (rtmp == NULL) {
         free(stmp);
         printf("nsl_corr_fft_type(): ERROR allocating memory for 'rtmp'!\n");
         return -1;
     }
 
     if (type == nsl_corr_type_linear) {
         for (i = 0; i < maxlag; i++)
             stmp[i] = 0.;
         for (i = 0; i < n; i++)
             stmp[i + maxlag] = s[i];
         for (i = n + maxlag; i < size; i++)
             stmp[i] = 0;
         for (i = 0; i < m; i++)
             rtmp[i] = r[i];
         for (i = m; i < size; i++)
             rtmp[i] = 0;
     } else { // circular
         for (i = 0; i < n; i++)
             stmp[i] = s[i];
         for (i = n; i < N; i++)
             stmp[i] = 0.;
         for (i = 0; i < m; i++)
             rtmp[i] = r[i];
         for (i = m; i < N; i++)
             rtmp[i] = 0.;
     }
 
     int status;
 #ifdef HAVE_FFTW3 // already wraps output
     status = nsl_corr_fft_FFTW(stmp, rtmp, oldsize, out);
 #else // GSL
     status = nsl_corr_fft_GSL(stmp, rtmp, size, out);
 #endif
 
     free(stmp);
     free(rtmp);
 
     /* normalization */
     switch (normalize) {
     case nsl_corr_norm_none:
         break;
     case nsl_corr_norm_biased:
         for (i = 0; i < oldsize; i++)
             out[i] = out[i] / N;
         break;
     case nsl_corr_norm_unbiased:
         for (i = 0; i < oldsize; i++) {
             size_t norm = i < oldsize / 2 ? i + 1 : oldsize - i;
             out[i] = out[i] / norm;
         }
         break;
     case nsl_corr_norm_coeff: {
         double snorm = cblas_dnrm2((int)n, s, 1);
         double rnorm = cblas_dnrm2((int)m, r, 1);
         for (i = 0; i < oldsize; i++)
             out[i] = out[i] / snorm / rnorm;
         break;
     }
     }
 
     // reverse array for circular type
     if (type == nsl_corr_type_circular) {
         for (i = 0; i < N / 2; i++) {
             double tmp = out[i];
             out[i] = out[N - i - 1];
             out[N - i - 1] = tmp;
         }
     }
 
     return status;
 }
 
 #ifdef HAVE_FFTW3
 int nsl_corr_fft_FFTW(double s[], double r[], size_t n, double out[]) {
     if (n == 0)
         return -1;
 
     const size_t size = 2 * (n / 2 + 1);
     double* in = (double*)malloc(size * sizeof(double));
     fftw_plan rpf = fftw_plan_dft_r2c_1d((int)n, in, (fftw_complex*)in, FFTW_ESTIMATE);
 
     fftw_execute_dft_r2c(rpf, s, (fftw_complex*)s);
     fftw_execute_dft_r2c(rpf, r, (fftw_complex*)r);
     fftw_destroy_plan(rpf);
 
     size_t i;
 
     // multiply
     for (i = 0; i < size; i += 2) {
         double re = s[i] * r[i] + s[i + 1] * r[i + 1];
         double im = s[i + 1] * r[i] - s[i] * r[i + 1];
 
         s[i] = re;
         s[i + 1] = im;
     }
 
     // back transform
     double* o = (double*)malloc(size * sizeof(double));
     fftw_plan rpb = fftw_plan_dft_c2r_1d((int)n, (fftw_complex*)o, o, FFTW_ESTIMATE);
     fftw_execute_dft_c2r(rpb, (fftw_complex*)s, s);
     fftw_destroy_plan(rpb);
 
     for (i = 0; i < n; i++)
         out[i] = s[i] / n;
 
     free(in);
     free(o);
     return 0;
 }
 #endif
 
 int nsl_corr_fft_GSL(double s[], double r[], size_t n, double out[]) {
     gsl_fft_real_workspace* work = gsl_fft_real_workspace_alloc(n);
     gsl_fft_real_wavetable* real = gsl_fft_real_wavetable_alloc(n);
 
     /* FFT s and r */
     gsl_fft_real_transform(s, 1, n, real, work);
     gsl_fft_real_transform(r, 1, n, real, work);
     gsl_fft_real_wavetable_free(real);
 
     size_t i;
     /* calculate halfcomplex product */
     out[0] = s[0] * r[0];
     for (i = 1; i < n; i++) {
         if (i % 2) { /* Re */
             out[i] = s[i] * r[i];
             if (i < n - 1) /* when n is even last value is real */
                 out[i] += s[i + 1] * r[i + 1];
         } else /* Im */
             out[i] = s[i] * r[i - 1] - s[i - 1] * r[i];
     }
 
     /* back transform */
     gsl_fft_halfcomplex_wavetable* hc = gsl_fft_halfcomplex_wavetable_alloc(n);
     gsl_fft_halfcomplex_inverse(out, 1, n, hc, work);
     gsl_fft_halfcomplex_wavetable_free(hc);
     gsl_fft_real_workspace_free(work);
 
     return 0;
 }