#!/usr/bin/python

from dscr import dscr

import scipy as sp

def myc2d(G,Ts):

    """ Produces numerator and denominator of discrete transfer 

    function in powers of z^{-1}

    G is continuous transfer function; time delays are not allowed

    Ts is the sampling time, all in consistent time units. """

    H = dscr(G,Ts)

    num1, den1 = H.num, H.den

    A = den1[::-1]

    num2 = num1[::-1]

    nonzero = sp.find(num1)

    B = num2(nonzero)

    k = len(den1) - len(num1)

    return B,A,k