% Part (c)

omega = [-10:0.5:10];
sigma = -1 + (1/8)*[1:32];
[sigmagrid,omegagrid] = meshgrid(sigma,omega);
sgrid = sigmagrid + j*omegagrid;
H1 = polyval(b1,sgrid) ./ polyval(a1,sgrid);
mesh(sigma,omega,abs(H1));
title('H_1(s)');
xlabel('\sigma=\Re\{s\}');
ylabel('\omega=\Im\{s\}');
print H1_surf.eps -deps
