import scipy as sp

from scipy import linalg

from scipy import signal

def dscr(H,Ts):

    """ Given a Continuous system and a Time step, returns a discretized system."""

    (n,m) = H.B.shape

    S = sp.zeros((n+m,n+m))

    S[:n,:n] = H.A

    S[:n,n:] = H.B

    s = linalg.expm(S*Ts)

    f = s[:n,:n]

    g = s[:n,n:]

    Hd = signal.lti(f, g, H.C, H.D)

    return Hd