bugGNU Octave - Bugs: bug #40932, control package: system format...

 
 

bug #40932: control package: system format affects computation of controller

Submitter:  None
Submitted:  Tue 17 Dec 2013 12:38:25 AM UTC
   
 
Category:  Octave Package Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Performance
Status:  Fixed Assigned to:  None
Originator Name:  Saul Mtakula Originator Email:  -email is unavailable-
Open/Closed:  * Closed Release:  * 3.6.4
Operating System:  * Any Fixed Release:  None
Planned Release:  None
* Mandatory Fields

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Sun 31 May 2015 05:59:52 PM UTC, comment #5: 

Closing as fixed.

The attached file1 does work with the current control package, although the attached file2 script doesn't work anymore, but that's a separate issue.

Mike Miller <mtmiller>
Group Member
Tue 06 May 2014 03:02:32 PM UTC, comment #4: 

control-2.6.4 features now transfer function specific horzcat and vertcat operators. This avoids conversion to state-space and back in the following expression:


G=[g11 g12 g13; g21 g22 g23; g31 g32 g33];


Lukas Reichlin <paramaniac>
Wed 18 Dec 2013 08:38:30 AM UTC, comment #3: 

Thanks for your report. I can confirm the problem with file1.m on my Mac:

error: ncfsyn: 2: the Z-Riccati equation is not solved successfully
error: memory exhausted or requested size too large for range of Octave's index type -- trying to return to prompt

The problem is line 20 in file1.m:

G=[g11 g12 g13; g21 g22 g23; g31 g32 g33];

With the current implementation of horzcat and vertcat, transfer function interconnections are calculated in state-space, requiring several conversions back and forth. This causes the extremely high model orders of G and Gss due to numerical problems. The solution is described in my projects file for quite some time:
http://sourceforge.net/p/octave/control/ci/default/tree/devel/PROJECTS
It looks like I should finally tackle this problem!

Lukas Reichlin <paramaniac>
Tue 17 Dec 2013 11:47:29 PM UTC, comment #2: 

Adding the control package maintainer in CC to respond, for real this time.

Mike Miller <mtmiller>
Group Member
Tue 17 Dec 2013 02:06:47 PM UTC, comment #1: 

Adding the control package maintainer in CC to respond.

Mike Miller <mtmiller>
Group Member
Tue 17 Dec 2013 12:38:25 AM UTC, original submission:  

Two example scripts for computation of the Glover-Macfarlane H infinity controller for a 3x3 (input-output) system (G)are are attached. For the exact same system the script in file1.m fails while it succeeds with the script in file2.m. The major difference appears the way the system G (and Wi) are defined.
With file1.m the error report is
"The X-Riccatti equation is not solved sucessfully"
"memory exhausted or requested size too large for range of Octave's index type -- try to return to prompt"

Anonymous

 

(Note: upload size limit is set to 16384 kB, after insertion of the required escape characters.)

Attach Files:
   
   
Comment:
   

Attached Files
file #29982:  file1.m added by None (811B - text/plain)
file #29983:  file2.m added by None (1KiB - text/plain)

 

Depends on the following items: None found

Items that depend on this one: None found

 

Carbon-Copy List
  • -email is unavailable- added by paramaniac (Posted a comment)
  • -email is unavailable- added by mtmiller
  • -email is unavailable- added by mtmiller (Posted a comment)
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    Follow 7 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2015-05-31 mtmiller StatusNone Fixed
        Open/ClosedOpen Closed
        Operating SystemMicrosoft Windows Any
    2013-12-17 mtmiller Carbon-Copy- Added paramaniac
    2013-12-17 mtmiller Summarysystem format (control toolbox) affects computation of controller control package: system format affects computation of controller
    2013-12-17 None Attached File- Added file1.m, #29982
        Attached File- Added file2.m, #29983

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