I am using pzmap where poles and zeros are ploted but my question how can i see poles on unit circle only not zeros?

I am using frequency response analysis and i want to plot the poles of the transfer function on unit circle without ploting zeros. Can anyone help me how can i do that?

Answer 1

[Erivelton Gualter]

You can extract the pole and zeros and construct your model again using zpk for example.

Check the following example:

    s = tf('s');
    G = (s+0.5)/(s^2+s-0.5);

    [P, Z] = pzmap(G);

    G_without_zeros = zpk(P,[],1);

    subplot(211); zplane(Z,P); title('Ploting Poles and Zeros on Unit Circle');
    subplot(212); zplane(Z,[]); title('Ploting only Zeros on Unit Circle');

[Muhammad]

Thank you very much for your answer. Does this wok with hold on function? Because i want to plot many poles under variation of one parameter.

[Muhammad]

because if i plot the graph multiple time using hold on function its limits are changed.

[Erivelton Gualter]

I believe you will be fine. Just ask if you face a problem.

[Walter Roberson]

In R2014b and later, if you "hold on" then the xlim and ylim should be preserved. In R2014a and earlier, you needed to "hold all" to have the limits preserved.

[Muhammad]

Thank you very much, your suggestions worked. Thank you.