[Octave-bug-tracker] [bug #56037] qp exits with an indexing error for a specific input with OpenBLAS

[Mike Miller]

Update of bug #56037 (project octave):

                  Status:               Confirmed => Patch Submitted        

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Follow-up Comment #10:

> it will probably take some gdb and/or printf-debugging to see where it comes
from.

I did this now.

Attached is vars.txt, which is a set of local variables extracted from the
'qp.m' function file at the point of the bad call to the '__qp__' function.
The error is reproducible for me with


./run-octave -cli --eval "load vars.txt; __qp__ (x0, H, q, A, b, Ain, bin,
maxit);"


This error message comes from the octave::out_of_range exception in liboctave,
so I simply set a breakpoint on the exception constructor, and the error is
raised in '__qp__.cc' line 313 (on the stable branch):

https://hg.savannah.gnu.org/hgweb/octave/file/c3716220d5b9/libinterp/corefcn/__qp__.cc#l313

Which led me to discover a typo in that section of code. The attached
changeset fixes this on the stable branch. I could use some help wording the
commit message, since this is not my area of expertise. It would also be
better if we had a more well-tested and reliable function to get both the
minimum value and index from a vector instead of using these ad-hoc loops.

(file #46703, file #46704)
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Additional Item Attachment:

File name: vars.txt                       Size:1 KB
    <https://savannah.gnu.org/file/vars.txt?file_id=46703>

File name: qp.diff                        Size:0 KB
    <https://savannah.gnu.org/file/qp.diff?file_id=46704>



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