den=conv([1,1],conv([1,2],conv([1,3],[1,4])));
num=[1,3,4]; G=tf(num,den); tau=0.5;
t=0:0.01:5; Y=[];
for i=1:6
   [nP,dP]=pade(tau,i); GP=tf(nP,dP);
   G_c=feedback(G*GP,1);
   Y=[Y, step(G_c,t)];
end
plot(t,Y)

Y=[]; tau=0.5;
for i=1:6
   [nP,dP]=pade(tau,i); GP=tf(nP,dP);
   G_c=feedback(G,GP); set(G_c,'Td',tau);
   y=step(G_c,t);
   Y=[Y, y];
end
plot(t,Y)

tau=0.5; [nP,dP]=pade(tau,3); GP=tf(nP,dP);
G_c=feedback(G,GP); set(G_c,'Td',tau);
[y1,t1]=step(G_c); [y2,t2]=impulse(G_c);
plot(t1,y1), figure, plot(t2,y2)