Plotting amplitude response and phase

Hi,

I want to plot the amplitude and the phase response of the following system:

I have the following code, but need help with the plots.

% Parameters
fs = 2000;
dt = 1/fs;
r = 0.99;
w0 = 700;
% Transfer function
numerator = [1,-2*cos(700),1];
denominator = [1,-2*cos(700)*r,r^2];
sys = tf(numerator,denominator,dt,'Variable','z^-1')

Answer 1

[Arvind Sathyanarayanan]

You can use the bode command to get the magnitude and phase response. Try:

bode(sys);

[Dennis Weimer]

This is working, but the plot doesn't fit to the following sketch.

Is there a possibbility, to change the scale, that it fits?