bugGNU Octave - Bugs: bug #56026, Incorrect output of generalized...


bug #56026: Incorrect output of generalized eigenvalue problem

Submitted by:  None
Submitted on:  Fri 29 Mar 2019 05:06:42 AM UTC  
Category:  Octave Function Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  Fixed Assigned to:  None
Originator Name:  Originator Email:  -email is unavailable-
Open/Closed:  Closed Release:  5.1.0
Operating System:  Any

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Mon 01 Apr 2019 09:49:22 PM UTC, comment #4: 

I fixed this on the stable branch here (https://hg.savannah.gnu.org/hgweb/octave/rev/fc73dafece57).

Closing report.

Rik <rik5>
Project Administrator
Mon 01 Apr 2019 07:53:22 PM UTC, comment #3: 

That makes sense.  It should follow the same syntax as for calc_rev.  So

  F77_XFCN (zggev, ZGGEV, (F77_CONST_CHAR_ARG2 ("N", 1),
                           F77_CONST_CHAR_ARG2 (calc_rev ? "V" : "N", 1),

should be

  F77_XFCN (zggev, ZGGEV, (F77_CONST_CHAR_ARG2 (calc_lev ? "V" : "N", 1),
                           F77_CONST_CHAR_ARG2 (calc_rev ? "V" : "N", 1),

Rik <rik5>
Project Administrator
Mon 01 Apr 2019 07:38:51 PM UTC, comment #2: 

The problem is in the first argument passed to zggev (EIG.cc). It should be

F77_CONST_CHAR_ARG2 (calc_lev ? "V" : "N", 1)

(two occurrences).

Marco Caliari <caliari>
Project Member
Fri 29 Mar 2019 03:20:47 PM UTC, comment #1: 

Confirmed.  I've attached a simple test script to illustrate the problem.

A = magic(4);
B = complex (magic(4), magic(4));
[v,l,w] = eig (A,B)

I tested back to Octave version 4.2.1 and this problem has always been present.  Apparently there was not a test for this in the test suite.

(file #46661)

Rik <rik5>
Project Administrator
Fri 29 Mar 2019 05:06:42 AM UTC, original submission:  

Calling eig function with the following form

[V, LAMBDA, W] = eig (A, B)

returns a zero matrix on W when the inputs are complex.

This problem doesn't occur with qz function



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Attach Files:

Attached Files
file #46661:  tst_eig.m added by rik5 (69B - text/x-matlab)


Depends on the following items: None found

Items that depend on this one: None found


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    Follow 5 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2019-04-01 rik5 StatusConfirmed => Fixed
        Open/ClosedOpen => Closed
    2019-03-29 rik5 Attached File- => Added tst_eig.m, #46661
        StatusNone => Confirmed
        Operating SystemMicrosoft Windows => Any

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