num=input('input the numerator polynomial coefficient vector =:');
den=input('input the denominator polynomial coefficient vector =:');
%reg=input('input the frequency region w=');
w=0:0.01:2*pi;

[h,w]=freqz(num,den,w);
r=real(h);
i=imag(h);

subplot(2,2,1)
plot(w/(pi),abs(h));axis([0,2,0,1.1*max(abs(h))])
grid on;
title('Magnitude response');
xlabel('Frequency (pi)')