bugGNU Octave - Bugs: bug #51249, center() relies on broadcasting


bug #51249: center() relies on broadcasting

Submitted by:  Guillaume <gyom>
Submitted on:  Fri 16 Jun 2017 02:10:26 PM UTC  
Category:  Octave Function Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Unexpected Error
Status:  Fixed Assigned to:  None
Originator Name:  Guillaume Open/Closed:  Closed
Release:  dev Operating System:  Any

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Tue 08 Aug 2017 03:54:40 PM UTC, comment #4:

I pushed the cset here (http://hg.savannah.gnu.org/hgweb/octave/rev/724fe19b50dc).

Rik <rik5>
Project Administrator
Tue 08 Aug 2017 09:52:15 AM UTC, comment #3:

Thanks Rik and sorry for having forgotten about this. You cset fixes the problem. I haven't come across other places in the code where broadcasting was an issue.

Guillaume <gyom>
Mon 07 Aug 2017 04:07:57 PM UTC, comment #2:

Try the attached cset center.cset. If there are other common uses of broadcasting it would be best to find them now and temporarily replace them.

(file #41448)

Rik <rik5>
Project Administrator
Fri 16 Jun 2017 03:43:21 PM UTC, comment #1:

It would be okay to modify center until this is fixed. If you can submit a proposed patch that would help. In the code, before the modification, add a note about why this is being done and when it can be reverted. Something like

## FIXME: Use bsxfun, rather than broadcasting, until broadcasting
## supports diagonal and sparse matrices (Bugs #41441, #35787).

Rik <rik5>
Project Administrator
Fri 16 Jun 2017 02:10:26 PM UTC, original submission:

The fact that center() relies on broadcasting makes it crash when the input is a sparse or diagonal matrix:

>> center (eye (3))
error: center: operator -: nonconformant arguments (op1 is 3x3, op2 is 1x3)
error: called from
center at line 72 column 12
>> center (sparse (rand (3)))
error: center: operator -: nonconformant arguments (op1 is 3x3, op2 is 1x3)
error: called from
center at line 72 column 12

These limitations of broadcasting are known (see bug #41441 and bug #35787) but are quite annoying when core functions rely on it - I came across this while calling var() on a sparse matrix.

If fixing the mentioned bugs are long term projects, would it be ok to modify center() not to rely on broadcasting and use bsxfun() instead?

Guillaume <gyom>


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

Attach Files:

Attached Files
file #41448:  center.cset added by rik5 (1KiB - application/octet-stream)


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    Follow 5 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2017-08-08 rik5 StatusPatch Submitted => Fixed
        Open/ClosedOpen => Closed
    2017-08-07 rik5 Attached File- => Added center.cset, #41448
        StatusConfirmed => Patch Submitted
    2017-06-16 rik5 StatusNone => Confirmed

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