% ex4_20
% 已知多變量系統的傳遞函數矩陣，繪制格希哥仁圓和格希哥仁帶
clear;num={[1],[0.75];[0.75],[1]};
den={[1 1],[2 1];[2 1],[0.5 1]};
G=tf(num,den);
b=10;
for i=1:2;
    for k=1:2
        w=[0,logspace(-1,0.2,b)];
        gg(i,k,:)=polyval(deconv(den{i,k},num{i,k}),j*w);
    end;
end;
figure('pos',[100,100,400,210],'color','w');
    g(1,:)=gg(1,1,:);
    r(1,:)=abs(gg(1,2,:));
    g(2,:)=gg(2,2,:);
    r(2,:)=abs(gg(2,1,:));
for l=1:2
    axes('pos',[0.05+0.5*(l-1) 0.2 0.4 0.7]);
    for n=1:b+1
        t=0:.01:2*pi;
        x(n,:)=r(l,n).*cos(t)+real(g(l,n));
        y(n,:)=r(l,n).*sin(t)+imag(g(l,n));
        plot(x(n,:),y(n,:));
        hold on;
    end;
grid;
plot(g(l,:)); 
end;