Transfer function to pole zero diagram

Question

Jonathan George 2022-3-26

0
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https://ww2.mathworks.cn/matlabcentral/answers/1681049-transfer-function-to-pole-zero-diagram

回答： Paul 2022-3-26

Is there any way to represent a discrete-domain transfer function [H(z)] with a pole zero diagram in MATLAB? And perhaps even vice-versa?

Thanks in advance.

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Answer 1

Paul 2022-3-26

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1681049-transfer-function-to-pole-zero-diagram#answer_927344

在 MATLAB Online 中打开

The answer to the first question is to use pzplot()

H = tf([1 .5],[1 2.5 3.125],1)

H = z + 0.5 ------------------- z^2 + 2.5 z + 3.125 Sample time: 1 seconds Discrete-time transfer function.

pzplot(H)

axis equal

Not sure about the second question. How would the pole-zero diagram be represented in Matlab for input to some function from which the tf is computed? If the poles and zeros are known then

z = -0.5; p = -1.25 + 1j*[1.25 -1.25];
H = zpk(z,p,1,1)
H =
 
        (z+0.5)
  --------------------
  (z^2 + 2.5z + 3.125)
 
Sample time: 1 seconds
Discrete-time zero/pole/gain model.
H = tf(H)
H =
 
        z + 0.5
  -------------------
  z^2 + 2.5 z + 3.125
 
Sample time: 1 seconds
Discrete-time transfer function.