p165.m

反馈控制系统设计与分析（matlab程序）

wn=1; zeta=[0.1:0.1:1,2]; 
w=logspace(-1,1); X=[]; Y=[];
for i=1:length(zeta)
   x=-wn*wn./(4*zeta(i)^2*wn^2+w.^2);
   y=-2*zeta(i)*wn^3./(w.*(4*zeta(i)^2*wn^2+w.^2));
   X=[X, x']; Y=[Y, y'];
end
plot(X,Y), axis('square')
xlabel('Real Axis'); ylabel('Imag Axis')