www.gusucode.com > signal 案例源码程序 matlab代码 > signal/IIRFilterImpulseResponseLengthSecondOrderSectionsExample.m
%% IIR Filter Effective Impulse Response Length -- Second-Order Sections % Design a 4th-order lowpass elliptic filter with a cutoff frequency of $0.4\pi$ % rad/sample. Specify 1 dB of passband ripple and 60 dB of stopband attenuation. % Design the filter in pole-zero-gain form and obtain the second-order section % matrix using |zp2sos|. Determine the effective impulse response sequence length % from the second-order section matrix. % Copyright 2015 The MathWorks, Inc. [z,p,k] = ellip(4,1,60,.4); [sos,g] = zp2sos(z,p,k); len = impzlength(sos)