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.

FIR Filters

The denominator of FIR filters is, by definition, equal to 1. To use the filter function with the b coefficients from an FIR function, use y = filter(b,1,x) .

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