% Part (b)

omega = linspace(-10,10,1000);
h1 = freqs(b1,a1,omega);
plot(omega,abs(h1));
title('|H_1(j\omega)|');
xlabel('\omega');
print H1_freq.eps -deps

% Note that the peaks for abs(h1) are at omega == 4 and -4,
% which correspond to the points on the imaginary axis closest
% to the poles.
