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*reg:2*pi*reg;

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

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