# scipy.signal.step

scipy.signal.step(system, X0=None, T=None, N=None)

  Step response of continuous-time system.

  Parameters:
    system an instance of the LTI class or a tuple of array_like

      describing the system. The following gives the number of elements in the tuple and the interpretation:

      > - 1 (instance of `lti`)

      > - 2 (num, den)

      > - 3 (zeros, poles, gain)

      > - 4 (A, B, C, D)

    X0 array_like, optional

      Initial state-vector (default is zero).

    T array_like, optional

      Time points (computed if not given).

    N int, optional

      Number of time points to compute if T is not given.

  Returns:
    T 1D ndarray

      Output time points.

    yout 1D ndarray

      Step response of system.

  Notes

  If (num, den) is passed in for `system`, coefficients for both the numerator and denominator should be specified in descending exponent order (e.g. `s^2 + 3s + 5` would be represented as `[1, 3, 5]`).

  Examples

      >>> from scipy import signal
      >>> import matplotlib.pyplot as plt
      >>> lti = signal.lti([1.0], [1.0, 1.0])
      >>> t, y = signal.step(lti)
      >>> plt.plot(t, y)
      >>> plt.xlabel('Time [s]')
      >>> plt.ylabel('Amplitude')
      >>> plt.title('Step response for 1. Order Lowpass')
      >>> plt.grid()