qerbt.py 文件源码

def fftfilt(b, x, *n):
    N_x = len(x)
    N_b = len(b)
    N = 2**np.arange(np.ceil(np.log2(N_b)),np.floor(np.log2(N_x)))
    cost = np.ceil(N_x / (N - N_b + 1)) * N * (np.log2(N) + 1)
    N_fft = int(N[np.argmin(cost)])
    N_fft = int(N_fft)    
    # Compute the block length:
    L = int(N_fft - N_b + 1)
    # Compute the transform of the filter:
    H = np.fft.fft(b,N_fft)
    y = np.zeros(N_x, x.dtype)
    i = 0
    while i <= N_x:
        il = np.min([i+L,N_x])
        k = np.min([i+N_fft,N_x])
        yt = np.fft.ifft(np.fft.fft(x[i:il],N_fft)*H,N_fft) # Overlap..
        y[i:k] = y[i:k] + yt[:k-i]                          # and add
        i += L
    return y