std :: dsp::dct
#include <std/dsp/dct.h> source ยท definition
#include <std/dsp/dct.h>
int idct3([]const double in, []double out)
Exact inverse of dct2: x[n] = (1/N) * (X[0] + 2*sum_{k=1}^{N-1} X[k] * cos(pi/N * (n+0.5) * k)).