[Octave-bug-tracker] [bug #61355] [octave forge] (control) Error on phase value of bode and margin plots

[Luiz Antonio Maccari Junior]

Follow-up Comment #6, bug #61355 (project octave):

An additional bug was detected. If you insert the values of the frequencies in
the bode  function for frequencies after the resonance the phase values return
NaN. Example:

s = tf('s');

TF2 = 1/(s^5*(s+2)*(s+10)*(s^2+100))

w = [9:0.1:11];
[mag, fase] = bode(TF2,w)


However if we use the bode function without specifying the frequencies the
bode plot can give a phase plot with finite values.

 Studying the bode function I see the problem related with the function unwrap
which uses a summation and when we have an ideal resonance the argument of the
frequency response is NaN. To bypass this error it is needed to put a damping
values for the resonant. As for example:

s = tf('s');

TF2 = 1/(s^5*(s+2)*(s+10)*(s^2+0.001+100))

w = [9:0.1:11];
[mag, fase] = bode(TF2,w)



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