`scipy.signal._signaltools:lfiltic`

source: /scipy/signal/_signaltools.py :2251

Signature

def lfiltic ( b , a , y , x = None )

Summary

Construct initial conditions for lfilter given input and output vectors.

Extended Summary

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.

Returns

zi : ndarray: The state vector zi = {z_0[-1], z_1[-1], ..., z_K-1[-1]}, where K = max(M, N).

Notes

Array API Standard Support

lfiltic has experimental support for Python Array API Standard compatible backends in addition to NumPy. Please consider testing these features by setting an environment variable SCIPY_ARRAY_API=1 and providing CuPy, PyTorch, JAX, or Dask arrays as array arguments. The following combinations of backend and device (or other capability) are supported.

====================  ====================  ====================
Library               CPU                   GPU
====================  ====================  ====================
NumPy                 ✅                     n/a                 
CuPy                  n/a                   ✅                   
PyTorch               ✅                     ⛔                   
JAX                   ✅                     ⛔                   
Dask                  ⚠️ computes graph     n/a                 
====================  ====================  ====================

See dev-arrayapi for more information.

Aliases

scipy.signal.lfiltic