[bug #68196] Wrong phase in bode plot

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URL:
  <https://savannah.gnu.org/bugs/?68196>

                 Summary: Wrong phase in bode plot
                   Group: GNU Octave
               Submitter: controldesigner
               Submitted: Mon 30 Mar 2026 06:53:16 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Incorrect Result
                  Status: None
             Assigned to: None
         Originator Name:
        Originator Email:
             Open/Closed: Open
         Discussion Lock: Unlocked
                 Release: 11.1.0
        Operating System: GNU/Linux
           Fixed Release: None
         Planned Release: None


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Follow-up Comments:


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Date: Mon 30 Mar 2026 06:53:16 PM UTC By: controldesigner <controldesigner>
I am getting incorrect bode plot results when plotting a discrete time
integrator.

example:
w = 2*pi*[0.001:0.001:50];
Ts = 1/100;
z = tf('z',Ts);
G = Ts/2 * (z+1)/(z-1);
[M,P,W] = bode(G, w);

P is just zeros

vs

H = freqresp(G, w);
angle(H)

angle(H) results in -1.5708






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