example6_24.m

<MATLAB 7辅助控制系统设计与仿真>书籍内的源代码.

num=[1 1];
den=conv([1 2],conv([1 2],[1 2]));
w=logspace(-1,2);
t=0.5;
[m1,p1]=bode(num,den,w);
p1=p1-t*w'*180/pi;
[n2,d2]=pade(t,4);
numt=conv(n2,num);
dent=conv(den,d2);
[m2,p2]=bode(numt,dent,w);
subplot(2,1,1);
semilogx(w,20*log10(m1),w,20*log10(m2),'y--');
subplot(2,1,2);
semilogx(w,p1,w,p2,'y--');
subplot(2,1,1);
grid on
title('Bode图')
xlabel('频率 (rad/sec)');
ylabel('增益 dB ');
subplot(2,1,2);
grid on
xlabel('频率 (rad/sec)');
ylabel('相位 deg');