% ex8.3
% FIR filter
h=fir1(40,0.5);
[h1,f1] = freqz(h,1,512,1);
% IIR filter
[b,a]=butter(20,0.5);
[h2,f2] = freqz(b,a,512,1);
% Plot on same axes
plot(f1,20*log10(abs(h1)+eps),f2,20*log10(abs(h2)+eps));
xlabel('Frequency');
ylabel('Magnitude (dB)');