def acorr_lpc(x, axis=-1):
    """Compute autocorrelation of x along the given axis.

    This compute the biased autocorrelation estimator (divided by the size of
    input signal)

    Notes
    -----
        The reason why we do not use acorr directly is for speed issue."""
    if not np.isrealobj(x):
        raise ValueError("Complex input not supported yet")

    maxlag = x.shape[axis]
    nfft = int(2 ** nextpow2(2 * maxlag - 1))

    if axis != -1:
        x = np.swapaxes(x, -1, axis)
    a = _acorr_last_axis(x, nfft, maxlag)
    if axis != -1:
        a = np.swapaxes(a, -1, axis)
    return a