G=tf(100,[0.04,1,0]);
[Gm,Pm,Wcg,Wcp]=margin(G); [Gm,Pm,Wcg,Wcp]

w=logspace(-1,3); [m,p]=bode(G,w);
subplot(211), semilogx(w,20*log10(m(:)))
subplot(212), semilogx(w,p(:))

Gc1=tf([0.0262 1],[0.0106,1]);  bode(Gc1,w)
G_o=Gc1*G;  [Gm,Pm,Wcg,Wcp]=margin(G_o); [Gm,Pm,Wcg,Wcp]

[m,p]=bode(G,w); [m1,p1]=bode(G_o,w);
subplot(211), semilogx(w,20*log10([m(:),m1(:)]))
subplot(212), semilogx(w,[p(:),p1(:)])
G_c1=feedback(G,1); G_c2=feedback(G_o,1);
[y,t]=step(G_c1); y=[y,step(G_c2,t)]; 
figure, plot(t,y)