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isfir(h)
isfir(h) determines whether filter h is an FIR filter, returning 1when the filter is an FIR filter, and 0 when it is IIR. isfir applies to dfilt, mfilt, and adaptfilt 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.
d = fdesign.lowpass;
h = design(d);
isfir(h)
ans =
1returns 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 =
1Use isfir with adaptive filters as well.
isallpass, islinphase, ismaxphase, isminphase, isreal, issos, isstable
![]() | isallpass | islinphase | ![]() |

Learn how to apply early verification to your development process through these technical resources.
How much time do you spend on testing to ensure implementation meets system-level requirements?
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