number of steps returned in the output.
x0 : array_like, optional
    The initial conditions on the state vector (zero by default).

Returns
-------
tout : ndarray
    Time values for the output, as a 1-D array.
yout : ndarray
    System response, as a 1-D array.
xout : ndarray, optional
    Time-evolution of the state-vector.  Only generated if the input is a
    `StateSpace` system.

See Also
--------
lsim, dstep, dimpulse, cont2discrete

Examples
--------
A simple integrator transfer function with a discrete time step of 1.0
could be implemented as:

>>> import numpy as np
>>> from scipy import signal
>>> tf = ([1.0,], [1.0, -1.0], 1.0)
>>> t_in = [0.0, 1.0, 2.0, 3.0]
>>> u = np.asarray([0.0, 0.0, 1.0, 1.0])
>>> t_out, y = signal.dlsim(tf, u, t=t_in)
>>> y.T
array([[ 0.,  0.,  0.,  1.]])

z7dlsim can only be used with discrete-time dlti systems.Nrö