>> num=conv(4,[1 5]); >> den1=conv([1 0],[1 0 3]); >> den2=conv([1 8],[1 2]); >> den=conv(den1,den2); >> subplot(1,3,1); >> rlocus(num,den); >> title('系统根轨迹图') >> hold on; >> subplot(1,3,2); >> nyquist(num,den) >> title('系统nyquist图') >> hold on; >> subplot(1,3,3); >> bode(num,den); >> title('系统bode图