%ex_6
clear all;
n=0:50;
x=cos(n*pi/3);
a=[1,0.95,0.9025];
b=[1/3,1/31/3];
yi=[2,3];
xi=0;
xic=filtic(b,a,yi,xi);
[A,B,C,D]=tf2ss(b,a);
figure(1)
subplot(3,1,1),dinitial(A,B,C,D,xic),title('零輸入響應')
subplot(3,1,2),dlsim(b,a,x),title('零狀態響應')
subplot(3,1,3),dlsim(A,B,C,D,x,xic),title('全響應')
y1=filter(b,a,zeros(1,length(n)),xic);
y2=filter(b,a,x);
y3=filter(b,a,x,xic);
figure(2)
subplot(3,1,1),stem(n,y1),title('零輸入響應')
subplot(3,1,2),stem(n,y2),title('零狀態響應')
subplot(3,1,3),stem(n,y3),title('全響應')
figure(3)
subplot(2,1,1),impz(b,a),title('沖激響應')
subplot(2,1,2),stepz(b,a),title('階躍響應')
u1=impseq(0,50,0);
u2=stepseq(0,50,0);
y4=filter(b,a,u1);
y5=filter(b,a,u2);
n=0:50;
figure(4)
subplot(2,1,1),stem(n,y4),title('沖激響應');
subplot(2,1,2),stem(n,y5),title('階躍響應');