# How to plot the magnitude and phase of a given transfer function(z-domain)?

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Daniel Ramirez on 27 Nov 2015 I tried approacting this by doing the LTI function:
>> z=tf('z'); >> H=0.203*[(1-z^-1)*(1-0.2743*z^-1+z^-2)]/[(1+0.2695*z^-1)*(1+0.4109*z^-1+0.6758*z^-2)]
H =
0.203 z^8 - 0.2587 z^7 + 0.2587 z^6 - 0.203 z^5
-----------------------------------------------
z^8 + 0.6804 z^7 + 0.7865 z^6 + 0.1821 z^5
I don't even know if I'm approacting this right, please I need help in doing this.
Daniel Ramirez on 28 Nov 2015
Edited: Daniel Ramirez on 28 Nov 2015
I think I did it?
L=1000;
dw=2*pi/L;
w = -pi:dw:pi-dw;
aa=[1,0.6804,0.953486,0.182128];
bb=[0.2031,-0.2588,0.2588,-0.2031];
HH=freqz(bb,aa,w);
mag=abs(HH);title('Magnitude response')
figure
phase=angle(HH);title('Phase response')
plot(w,mag)
plot(w,phase)
The next step that they want me to do is plot the impulse response. So anyone know how to go from the freq domain to the time domain(n)? This is what I'm struggling the most, any help would be appreciated.

Aik-Siong Koh on 8 Jul 2021

Edited: ANNALURU R R SREENIVASA MURTHY on 15 Nov 2021
You can use 'imp' function to plot impulse response.