% (a)
b = [1 2 0.75];
a = [1 -0.5];
bmin = polystab(b)*norm(b)/norm(polystab(b));
bmax = fliplr(bmin);
amin = polystab(a)*norm(a)/norm(polystab(a));
amax = fliplr(amin);
figure();
subplot 121
zplane(bmin,amin);title("Minimum Phase");
subplot 122
zplane(bmax,amax);title("Maximum Phase");
ismaxphase(bmax, amin)