extract_features.py 文件源码

def atal(x, order, num_coefs):
    x = np.atleast_1d(x)
    n = x.size
    if x.ndim > 1:
        raise ValueError("Only rank 1 input supported for now.")
    if not np.isrealobj(x):
        raise ValueError("Only real input supported for now.")
    a, e, kk = lpc(x, order)
    c = np.zeros(num_coefs)
    c[0] = a[0]
    for m in range(1, order+1):
        c[m] = - a[m]
        for k in range(1, m):
            c[m] += (float(k)/float(m)-1)*a[k]*c[m-k]
    for m in range(order+1, num_coefs):
        for k in range(1, order+1):
            c[m] += (float(k)/float(m)-1)*a[k]*c[m-k]
    return c