isfir

Determine if digital filter has finite impulse response

Syntax

flag =
isfir(d)

Description

example

flag = isfir(d) returns true if a digital filter, d, has a finite impulse response.

Examples

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FIR and IIR Digital Filters

Open Live Script

Use designfilt to design FIR and IIR versions of a highpass filter. Specify a normalized stopband frequency of 0.3 and a normalized passband frequency of 0.6. Verify that each filter is of the correct class. Display the frequency responses of the filters.

fir = designfilt('highpassfir','StopbandFrequency',0.3,'PassbandFrequency',0.6);
iir = designfilt('highpassiir','StopbandFrequency',0.3,'PassbandFrequency',0.6);
isfirFIR = isfir(fir)

isfirFIR = logical
   1

isiirFIR = isfir(iir)

isiirFIR = logical
   0

fvt = fvtool(fir,iir);
legend(fvt,'FIR','IIR')

Figure Figure 1: Magnitude Response (dB) contains an axes object. The axes object with title Magnitude Response (dB), xlabel Normalized Frequency ( times pi blank r a d / s a m p l e ), ylabel Magnitude (dB) contains 2 objects of type line. These objects represent FIR, IIR.

Input Arguments

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`d` — Digital filter
`digitalFilter` object

Digital filter, specified as a digitalFilter object. Use designfilt to generate a digital filter based on frequency-response specifications.

Example: d = designfilt('lowpassiir','FilterOrder',3,'HalfPowerFrequency',0.5) specifies a third-order Butterworth filter with normalized 3 dB frequency 0.5π rad/sample.