bugGNU Octave - Bugs: bug #46566, [octave forge] (control)...

 
 

bug #46566: [octave forge] (control) ctranspose of transfer function return wrong results

Submitter:  None
Submitted:  Sun 29 Nov 2015 03:50:01 PM UTC
   
 
Category:  Octave Package Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  Fixed Assigned to:  octave-forge
Originator Name:  bezkor Originator Email:  -email is unavailable-
Open/Closed:  * Closed Release:  * other
Operating System:  * Any Fixed Release:  None
Planned Release:  None
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Sun 09 Apr 2023 03:20:34 PM UTC, comment #4: 

This bug is not present in the latest version 3.5.2 anymore. Closing this report as fixed.


Torsten Lilge <ttl>
Group Member
Thu 24 Mar 2016 06:35:52 PM UTC, comment #3: 

For complex numbers j'=-j.

Because s=j*omega (complex number)

(s+1)' =(j*omega+1)'= (j)'*omega+1 = -s + 1

Simple rule: (s)'= -s

(s^2+s+1)'= (-s)^2 -s +1 = s^2-s+1

Anonymous
Sun 24 Jan 2016 05:23:45 PM UTC, comment #2: 

What does Matlab do with these?

s=tf('s')
ctranspose(s+1)
ctranspose(s^2+s+1)


Doug Stewart <dastew>
Sat 05 Dec 2015 11:23:18 PM UTC, comment #1: 

The lifehack solution: change indexing in function

control-3.0.0/@tfpoly/conj_ct.m

#p.poly(2:2:end) = -p.poly(2:2:end);

p.poly(end-1:-2:1) = -p.poly(end-1:-2:1);

Anonymous
Sun 29 Nov 2015 03:50:01 PM UTC, original submission:  

Wrong indexes range of coefficient of TF's num and den when conjugate.

Reproduce bug:

>> s=tf('s')

Transfer function 's' from input 'u1' to output ...
 y1:  s
Continuous-time model.

>> ctranspose(s+1)

Transfer function 'ans' from input 'u1' to output ...
 y1:  s - 1
Continuous-time model.
# expect as (-s+1)

>> ctranspose(s^2)+ctranspose(s+1)

Transfer function 'ans' from input 'u1' to output ...
 y1:  s^2 + s - 1
Continuous-time model.
# expect as (s^2-s+1)

>> ctranspose(s^2+s+1)

Transfer function 'ans' from input 'u1' to output ...
 y1:  s^2 - s + 1
Continuous-time model.

Anonymous

 

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  • -email is unavailable- added by ttl (Posted a comment)
  • -email is unavailable- added by jwe (Updated the item)
  • -email is unavailable- added by mtmiller (Updated the item)
  • -email is unavailable- added by dastew (Posted a comment)
  • -email is unavailable- added by siko1056 (Updated the item)
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    Follow 8 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2023-04-09 ttl StatusNeed Info Fixed
        Open/ClosedOpen Closed
    2017-08-13 jwe Summarycontrol package: ctranspose of transfer function return wrong results [octave forge] (control) ctranspose of transfer function return wrong results
    2016-05-17 mtmiller StatusNone Need Info
        Release4.0.0 other
        Operating SystemGNU/Linux Any
        Summarycontrol 3.0.0: ctranspose of TF function return wrong results control package: ctranspose of transfer function return wrong results
    2016-01-04 siko1056 Assigned toNone octave-forge

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