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

 
 

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

Submitted by:  None
Submitted on:  Sun 29 Nov 2015 03:50:01 PM UTC  
 
Category: Octave Forge PackageSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Incorrect Result
Status: Need InfoAssigned to: Octave Forge <octave-forge>
Originator Name: bezkorOriginator Email: -unavailable-
Open/Closed: OpenRelease: other
Operating System: Any

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Thu 24 Mar 2016 06:35:52 PM UTC, comment #3:

For complex numbers j'=-j.

Because s=j*omega (complex number)

(s+1)' =(jomega+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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Carbon-Copy List
  • -unavailable- added by jwe (Updated the item)
  • -unavailable- added by mtmiller (Updated the item)
  • -unavailable- added by dastew (Posted a comment)
  • -unavailable- added by siko1056 (Updated the item)
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    Follow 6 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Sun 13 Aug 2017 12:58:02 PM UTCjweSummarycontrol package: ctranspose of transfer function return wrong results=>[octave forge] (control) ctranspose of transfer function return wrong results
    Tue 17 May 2016 05:06:10 PM UTCmtmillerStatusNone=>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
    Mon 04 Jan 2016 10:46:21 PM UTCsiko1056Assigned toNone=>octave-forge

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