ms10r2.m

《数字信号处理实验(MATLAB版)》这

b=[2,3,0];
a=[1,0.4,1];
n=(0:500)*pi/500;
[h,w]=freqz(b,a,n);
db=20*log10(abs(h));
subplot(2,1,1),plot(w/pi,db);grid
axis([0,1,1.1*min(db),1.1*max(db)]);
ylabel('幅度');
subplot(2,1,2),plot(w/pi,angle(h));grid
axis([0,1,1.1*min(angle(h)),1.1*max(angle(h))]);
ylabel('相位');
xlabel('以pi为单位的频率');