# scipy.signal.impulse

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

  Impulse 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. Defaults to zero.

    T array_like, optional

      Time points. Computed if not given.

    N int, optional

      The number of time points to compute (if T is not given).

  Returns:
    T ndarray

      A 1-D array of time points.

    yout ndarray

      A 1-D array containing the impulse response of the system (except for singularities at zero).

  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

  Compute the impulse response of a second order system with a repeated root: `x''(t) + 2*x'(t) + x(t) = u(t)`

      >>> from scipy import signal
      >>> system = ([1.0], [1.0, 2.0, 1.0])
      >>> t, y = signal.impulse(system)
      >>> import matplotlib.pyplot as plt
      >>> plt.plot(t, y)