# persist state of digitalFilter

Suppose I created a digitalFilter using designfilt (in matlab).

I am interested in using it to filter windows (I dont have the whole data set offline).

When I call filter() with this filter and a window worth of samples I get a delay at the beginning every time.

How can I handle this ?

When I call filter in the form:

[filtered, state] = filter(b, a, window);


I can then call filter again in the form:

[filtered, state] = filter(b, a, next_window, state);


thus persisting the state and not creating a new filtering delay for every window.

How do I do that with a digitalFilter object ?