% Problem 7.6
A=[-0.154 0.004 0.178 0.075
   -1.25 -2.85  0     1.43
    0     1     0     0
   0.568 -0.277 0    -0.284]

B=[0.075; -0.727; 0; -2.05]

C=[1 0 0 0];

D=0;

[num,den]=ss2tf(A,B,C,D,1);
for j=1:length(num),
    if abs(num(j))<1.e-10
       num(j)=0;
    end
end
printsys(num,den,'s')
[p,z]=pzmap(num,den)
rlocus(num,den)
axis([-4 4 -1 1])
grid