C71.m

num=[1 5];
den=[1 3 2];
w=0.1:.01:100;
axis([log10(.1) log10(100) -50 50])
[mag,phase,w]=bode(num,den,w);
subplot(211),semilogx(w,20*log10(mag))
subplot(212),semilogx(w,phase)