Function std::minimum_phase

int minimum_phase([]const double x, unsigned long fftLen, []double outMinPhase)

'x' has 'n' samples (n <= fftLen); 'fftLen' must be a power of two (see fft.h) and should be comfortably larger than n for accurate cepstral liftering (a common rule of thumb: at least 4-8x n). 'outMinPhase' must have room for 'fftLen' samples — the full-length minimum-phase impulse response (its energy concentrates near the start; callers typically keep only the first n-ish samples).