Matlab: plotting magnitude and phase response I've got the frequency response $H(e^{j\omega}) = \frac{2 + 3.125e^{-2j\omega}}{1-0.9e^{-j\omega}+0.81e^{-2j\omega}}$, and I'm trying to figure out how to plot the magnitude response and the phase response in Matlab. Is there a simple way to do this?

Thank you in advance. This is my first post here, so please tell me if there's anything I forgot to add. 

Hal
@Hal: Unlike MBaz, I realize you weren't asking for information on the theory of signal processing. But, rather, you were asking a Matlab implementation question. I only have an old version of Matlab so I couldn't try Anthony's code. (Anthony was smart to insert that zero-valued coefficient.) But to plot the frequency mag. and phase responses of a discrete version of your filter, try these:

figure(1), freqz([2,0,3.125],[1,-0.9,0.81]);


or

freqz([2,0,3.125],[1,-0.9,0.81], 512, 'whole');