c122.m

matlab例程MATLAB 6.x版的内建数据类型（Built-in data type）就有5种以上

% We shall plot for 3 values of gamma: 0.83, 0.9, and 0.96.
a=0.83
for i=1:3
   num=[1 0 -1]; den=[1 -sqrt(2)*a a^2];
   W=-pi:pi/100:pi;
   H=freqz(num,den,W);
   if i==1, mag1=abs(H); phase1=angle(H); a=0.9;
   elseif i==2, mag2=abs(H); phase2=angle(H); a=0.96;
   else mag3=abs(H); phase3=angle(H);end;
end

subplot(2,1,1);
plot(W,mag1,W,mag2,W,mag3);grid;
subplot(2,1,2);
plot(W,phase1,W,phase2,W,phase3);grid