[Octave-bug-tracker] [bug #55244] error from mag2db(...) within bode(...) when using minreal on the input transfer function

[anonymous]

URL:
  <https://savannah.gnu.org/bugs/?55244>

                 Summary: error from mag2db(...) within bode(...) when using
minreal on the input transfer function
                 Project: GNU Octave
            Submitted by: None
            Submitted on: Wed 19 Dec 2018 03:05:36 PM UTC
                Category: Octave Function
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Unexpected Error
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 4.0.0
        Operating System: GNU/Linux

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Details:

I receive an error with the following code and feel it might be a bug.


pkg load control
pkg load signal
Lf = 330e-6;
Cf = 470e-6;
s = tf('s');
Z0min = minreal(s*Cf/(1+s^2*Lf*Cf))
Z0 = s*Cf/(1+s^2*Lf*Cf)
Z0tf = tf([Cf,0],[Lf*Cf,0,1])


The three Z0 transfer functions should be equivalent but when I call
bode(Z0min), I get the following error:


error: Invalid call to mag2db.  Correct usage is:

 -- Function File: DB = mag2db (MAG)
error: called from
    print_usage at line 90 column 5
    mag2db at line 44 column 5


The version info is as follows:

GNU Octave Version: 4.0.0
GNU Octave License: GNU General Public License
Operating System: Linux 4.4.0-139-generic #165-Ubuntu SMP Wed Oct 24 10:58:50
UTC 2018 x86_64
----------------------------------------------------------------------
Package Name  | Version | Installation directory
--------------+---------+-----------------------
     control *|   3.1.0 | /home/octave/control-3.1.0
      signal *|   1.4.0 | /home/octave/signal-1.4.0
    symbolic  |   2.7.1 | /home/octave/symbolic-2.7.1





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