Discrete Time fourier transform in MATLAB|PART 3

Code:

w=-4*pi:0.01:4*pi;
num=[2 1];
den=[1 -0.6];
h=freqz(num,den,w);
subplot(2,2,1);
plot(w/pi,abs(h));
ylabel('Magnitude');
subplot(2,2,2);
plot(w/pi,angle(h));
ylabel('Phase');
subplot(2,2,3);
plot(w/pi,real(h));
ylabel('Real');
subplot(2,2,4);
plot(w/pi,imag(h));

ylabel('Imaginary');