def poly2ac(poly, efinal):
results = rlevinson(poly, efinal)<EOL>return results[<NUM_LIT:0>]<EOL>
Convert prediction filter polynomial to autocorrelation sequence

    :param array poly: the AR parameters
    :param efinal: an estimate of the final error
    :return: the autocorrelation  sequence in complex format.

    .. doctest::

        >>> from numpy import array
        >>> from spectrum import poly2ac
        >>> poly = [ 1. ,  0.38 , -0.05]
        >>> efinal = 4.1895
        >>> poly2ac(poly, efinal)
        array([ 5.00+0.j, -2.00+0.j,  1.01-0.j])