Pole Zero Plot of Transfer Fucntion H(z)

I am having a transfer function H(z)

H(z)= ((z-1)(z-1)(z-2))/(z.z.z)

How can i have its pole zero map

i know abt pzmap but it is for continuous

[Fangjun Jiang]

Isn't that the poles and zeros already given?

Answer 1

[moonman]

is it good approach. i have actual H(z) in z(-1) form

   h = tf([1 -1],[1 -3 2],0.1,'variable','z^-1')

pzmap(h)

[Carla]

Yes, this will work, and pzmap works fine on discrete-time models.

Your h here is not the same as the transfer function in your original post, though, which you could create with:

H = zpk([1,1,2],[0,0,0],1,0.1)

(using 0.1 for sampling time since you used 0.1 to define h)

Answer 2

[Honglei Chen]

You can use zplane, you can specify either the zero/pole directly or the coefficients. For example, using your equation, you can do either

zplane([1;1;2],[0; 0; 0])

or

zplane(conv(conv([1 -1],[1 -1]),[1 -2]),[1 0 0 0])

See documentation for details

doc zplane

HTH

Answer 3

[Hassan]

h = tf([1 -1],[1 -3 2],0.1,'variable','z^-1')

pzmap(h)