bugGNU Octave - Bugs: bug #36015, unexpected sqp error


bug #36015: unexpected sqp error

Submitted by:  John W. Eaton <jwe>
Submitted on:  Tue 27 Mar 2012 03:28:12 PM UTC  
Category: Octave FunctionSeverity: 3 - Normal
Priority: 5 - NormalItem Group: Incorrect Result
Status: Patch SubmittedAssigned to: Lachlan Andrew <lachlan>
Originator Name: Open/Closed: Open
Release: devOperating System: GNU/Linux

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Sat 27 Feb 2016 05:23:14 AM UTC, comment #2:

There seem to be two problems here.

The clearest problem is that qp.m uses the wrong size matrices for C and the lower bound. From the comments in the code, Ain must have n columns (as it is multiplied by x), but a value of n-n_eq was being used.

I don't really understand the algorithm, so I can't confirm that that is the only bug, but since it is just changing the size of a vector of zeros or infinities, I assume that is the right fix.

Once that is fixed, qp returns an infeasible solution, and returns lambda=[]. This causes an error in sqp, so this patch sets lambda to its previous value if qp returns an infeasible solution. A warning is shown anyway, so the user knows not to trust the results; this just prevents an inexplicable error.

It would be great if someone who understands this code could check the changes.

(file #36487)

Lachlan Andrew <lachlan>
Project MemberIn charge of this item.
Fri 08 Nov 2013 09:38:30 PM UTC, comment #1:

The problem is still here in Octave 3.7.7+ (3851e5fde76d)

Julien Bect <jbect>
Tue 27 Mar 2012 03:28:12 PM UTC, original submission:

The following code

results in the error:

I found this bug report in an old set of messages that were never correctly posted to the -unavailable- mailing list.
Sorry for not posting it before now.

John W. Eaton <jwe>
Project Administrator


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Attach File(s):

Attached Files
file #36487:  bug_36015_sqp.cset added by lachlan (3kB - text/x-diff)


Depends on the following items: None found

Items that depend on this one: None found


Carbon-Copy List
  • -unavailable- added by lachlan (Updated the item)
  • -unavailable- added by jbect (Posted a comment)
  • -unavailable- added by mtmiller (Updated the item)
  • -unavailable- added by jwe (Submitted the item)
  • -unavailable- added by jwe

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    Follow 7 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Sat 27 Feb 2016 05:23:14 AM UTClachlanAttached File-=>Added bug_36015_sqp.cset, #36487
      StatusConfirmed=>Patch Submitted
      Assigned toNone=>lachlan
    Mon 28 Oct 2013 02:50:04 AM UTCmtmillerCategoryLibraries=>Octave Function
    Tue 27 Mar 2012 03:28:12 PM UTCjweCarbon-Copy-=>Added -unavailable-

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