ch4_2.m

清华大学《matlab 控制系统应用与实例》第一部分M文件的源码

clear
load y2data;

n=length(y2);
for i=5:n
    th=ar(y2(1:i),2);
    a0 = arxdata(th);
    a(i)=a0(2);
    b(i)=a0(3);
   th1=ar(a(1:i)',2);
    a1 = arxdata(th1);
    aa(i)=a1(2);
    bb(i)=a1(3);
    th2=ar(b(1:i)',2);
    a2 = arxdata(th2);
    aaa(i)=a2(2);
    bbb(i)=a2(3);
end


for i=2:n-1
    ap(i+1)=aa(i)*a(i)+bb(i)*a(i-1);
    bp(i+1)=aaa(i)*b(i)+bbb(i)*b(i-1);
    y(i+1)=ap(i+1)*y2(i)+bp(i+1)*y2(i-1);
    yy(i+1)=-a(i)*y2(i)-b(i)*y2(i-1);
end

t=[1:n]';
figure(1)
subplot(211)
plot(t,a,'r-', t,b,'b-')

subplot(212)
plot(t,y2,'r-',t,y,'b-',t,yy,'g-')

figure(2)
subplot(211)
plot(t,a,'r-', t,aa,'b-',t,aaa,'y-')

subplot(212)
plot(t,b,'r-', t,bb,'b-',t,bbb,'y-')