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isfir

Determine whether filter is FIR

Syntax

isfir(h)
isfir(hs)

Description

isfir(h) determines whether filter h is an FIR filter, returning 1 when the filter is an FIR filter, and 0 when it is IIR. isfir applies to dfilt and multirate filter System objects.

To determine whether h is an FIR filter, isfir(h) inspects filter h and determines whether the filter, in transfer function form, has a scalar denominator. If it does, it is an FIR filter.

isfir(hs) determines whether the filter System object™ hs is an FIR filter, returning 1 if true and 0 if false.

Examples

d = fdesign.lowpass;
h = design(d);
isfir(h)
ans =

     1

returns 1 for the status of filter h. The filter is an FIR structure with denominator reference coefficient equal to 1.

For multirate filters, isfir works the same way.

d = fdesign.interpolator(5); % Interpolate by 5.
h = design(d); % Use the default design method.
isfir(h)

ans =

     1

Introduced in R2011a

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