Signal Processing Toolbox™

filter

Filter data with recursive (IIR) or nonrecursive (FIR) filter

Description

filter is a MATLAB^® function.

Signal-Specific Information

Filter Method of DFILT

Filter is also an overloaded method of the discrete-time filter object (dfilt). You can pass an object handle, data, and optionally, the dimension into the filter method.

The MATLAB filter function describes a zi input for initial conditions. Note that the recommended way of passing initial conditions into a dfilt is by using the states property. For more information, see the dfilt reference page.

Filter Normalization

Using the filter function on b and a coefficients normalizes the filter by forcing the a₀ coefficient to be equal to 1.

Using the filter method on a dfilt object does not normalize the a₀ coefficient.

fftshift

filter2