Hz=tf([0.74 -2.54 2.5216],[1 0 0.64],0.1);
Hz
subplot(2,1,1);
pzmap(Hz);
hold on;
subplot(2,1,2);
impz([0.74 -2.54 2.5216],[1 0 0.64]);
hold on;
n=0:1:49;
Xn=(-2*(0.3)^n)+2*(0.8)^n);
y=filter([0.74 -2.54 2.5216],[1 0 0.64],Xn);
plot(y);