convolution.c

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/*
*   DSP API - a digital signal processing library for astronomy usage
*   Copyright © 2017-2022  Ilia Platone
*
*   This program is free software; you can redistribute it and/or
*   modify it under the terms of the GNU Lesser General Public
*   License as published by the Free Software Foundation; either
*   version 3 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
*   Lesser General Public License for more details.
*
*   You should have received a copy of the GNU Lesser 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 "dsp.h"
 
void dsp_convolution_convolution(dsp_stream_p stream, dsp_stream_p matrix) {
    int x, y, d;
    dsp_t mn = dsp_stats_min(stream->buf, stream->len);
    dsp_t mx = dsp_stats_max(stream->buf, stream->len);
    int* d_pos = (int*)malloc(sizeof(int)*stream->dims);
    for(y = 0; y < matrix->len; y++) {
        int* pos = dsp_stream_get_position(matrix, y);
        for(d = 0; d < stream->dims; d++) {
            d_pos[d] = stream->sizes[d]/2+pos[d]-matrix->sizes[d]/2;
        }
        x = dsp_stream_set_position(stream, d_pos);
        free(pos);
        if(x >= 0 && x < stream->magnitude->len)
            stream->magnitude->buf[x] *= sqrt(matrix->magnitude->buf[y]);
    }
    free(d_pos);
    dsp_fourier_idft(stream);
    dsp_buffer_stretch(stream->buf, stream->len, mn, mx);
}
 
void dsp_convolution_correlation(dsp_stream_p stream, dsp_stream_p matrix) {
    int x, y, d;
    dsp_t mn = dsp_stats_min(stream->buf, stream->len);
    dsp_t mx = dsp_stats_max(stream->buf, stream->len);
    int* d_pos = (int*)malloc(sizeof(int)*stream->dims);
    dsp_buffer_shift(matrix->magnitude);
    for(y = 0; y < matrix->len; y++) {
        int* pos = dsp_stream_get_position(matrix, y);
        for(d = 0; d < stream->dims; d++) {
            d_pos[d] = stream->sizes[d]/2+pos[d]-matrix->sizes[d]/2;
        }
        x = dsp_stream_set_position(stream, d_pos);
        free(pos);
        stream->magnitude->buf[x] *= sqrt(matrix->magnitude->buf[y]);
    }
    dsp_buffer_shift(matrix->magnitude);
    free(d_pos);
    dsp_fourier_idft(stream);
    dsp_buffer_stretch(stream->buf, stream->len, mn, mx);
}