%用傳輸函數(shù)求二階離散系統(tǒng)的階躍響應(yīng)
num=[1 -1 0];
den=[1 1.5 0.5];
n=0:20;
x=ones(1,length(n));
zi=[-1.5*2-0.5*1,-0.5*2];%zi=[-a1*y[-1]-a2*y[-2],-a2*y[-1]],a1
y=filter(num,den,x,zi);
stem(n,y);