test/common.c


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#include "common.h"
#include <math.h>

void dct4(float* out, const float* x, int N, float scale) {
    for (int k = 0; k < N; k++) {
        double sum = 0;
        for (int n = 0; n < N; n++) {
            sum += x[n] * cos((M_PI/N) * ((double)n + 0.5) * ((double)k + 0.5));
        }
        out[N - 1 - k] = sum * scale;
    }
}