# scipy.signal.lfiltic¶

scipy.signal.lfiltic(b, a, y, x=None)[source]

Construct initial conditions for lfilter given input and output vectors.

Given a linear filter (b, a) and initial conditions on the output y and the input x, return the initial conditions on the state vector zi which is used by lfilter to generate the output given the input.

Parameters: b : array_like Linear filter term. a : array_like Linear filter term. y : array_like Initial conditions. If N = len(a) - 1, then y = {y[-1], y[-2], ..., y[-N]}. If y is too short, it is padded with zeros. x : array_like, optional Initial conditions. If M = len(b) - 1, then x = {x[-1], x[-2], ..., x[-M]}. If x is not given, its initial conditions are assumed zero. If x is too short, it is padded with zeros. zi : ndarray The state vector zi = {z_0[-1], z_1[-1], ..., z_K-1[-1]}, where K = max(M, N).