bugGNU Octave - Bugs: bug #32251, Inv() returns incorrect results...

 
 

bug #32251: Inv() returns incorrect results when called on complex matrix

Submitter:  None
Submitted:  Wed 26 Jan 2011 01:59:20 AM UTC
   
 
Category:  None Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  None Assigned to:  None
Originator Name:  Greg Originator Email:  -email is unavailable-
Open/Closed:  * Closed Release:  * 3.2.4
Operating System:  * Microsoft Windows Fixed Release:  None
Planned Release:  None
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Wed 09 Mar 2011 05:02:05 AM UTC, comment #4: 

Closing report; no response to request for information in over a month.

Rik <rik5>
Group administrator
Wed 26 Jan 2011 07:20:31 PM UTC, comment #3: 

When you used the installer, which BLAS and LAPACK libraries did you choose and do they match your hardware?

Does the problem still occur if you use the "generic" option?

John W. Eaton <jwe>
Group administrator
Wed 26 Jan 2011 12:01:45 PM UTC, comment #2: 

Hi john,

I installed Octave from the binary distribution available from the Octave Forge Project. I will try to re-install and see if it changes anything.

Best Regards,
Greg

Anonymous
Wed 26 Jan 2011 03:05:08 AM UTC, comment #1: 

I can't duplicate this problem with Octave 3.2.4 or a copy of Octave built from the current development sources on my Debian system, so I suspect a problem with your LAPACK library.

Perhaps someone else with a Windows build of Octave can confirm the problem.

How did you install Octave?

If you built it from sources yourself, then What LAPACK library are you using?  How was it compiled?

John W. Eaton <jwe>
Group administrator
Wed 26 Jan 2011 01:59:20 AM UTC, original submission:  

If I create a complex matrix, A, as follows
A = [1+.1j,1e-5+100j;-5-2j,-1-j]

and then calculate the inverse by calling inv(A), the incorrect result of

inv(A) = [.00241-.00103i, .172+.0689i; .0000079-.00997i, -.00086+.00165i].

I believe the answer should be

inv(A) = [-.00103+.00242i, -.172+.0695i; .0000231-.0100i, -.000522-.00179i]

Clearly the answer is in the right direction, but something has gone awry.

Anonymous

 

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    Follows 1 latest change.

    Date Changed by Updated Field Previous Value => Replaced by
    2011-03-09 rik5 Open/ClosedOpen Closed

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