def zpk2ss(z, p, k):
return tf2ss(*zpk2tf(z, p, k))<EOL>
Zero-pole-gain representation to state-space representation

    Parameters
    ----------
    z, p : sequence
        Zeros and poles.
    k : float
        System gain.

    Returns
    -------
    A, B, C, D : ndarray
        State space representation of the system, in controller canonical
        form.