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Re: [Octave-bug-tracker] [bug #34850] Behaviour of chol(a,'lower')


From: Salvatore Filippone
Subject: Re: [Octave-bug-tracker] [bug #34850] Behaviour of chol(a,'lower')
Date: Mon, 20 Jan 2014 17:44:11 +0100

No, I did not have time then, and I did not work on the codes. I can
confirm that the workaround still works (as of the version I have
installed right now).
Looking at the source files the fix requires changing
  dbleCHOL::init (const Matrix& a, bool calc_cond)

and its friends to accept the lower/upper flag and pass it to the
inner call. to the LAPACK routine.
Something along the lines of the code I am attaching should work, but
I did *not* test it, and I cannot do it any time soon. But if Carlo
has time to test I can look at the results.
NOTE: for complex data, in cholinv_internal you'll need to add  std::conj .

BTW, I am not sure what happens in the sparse case...that's a whole
different game, and we'd need to look at the UMFPACK docs.
Salvatore

On Mon, Jan 20, 2014 at 10:27 AM, anonymous <address@hidden> wrote:
> Follow-up Comment #15, bug #34850 (project octave):
>
> The "bug" has not been really resolved
> but merely "worked around" by applying
> the patch in file #24462 .
>
> A "clean" fix would require using the correct
> LAPACK call rather than transposing the matrix
> twice as is currently done.
>
> Salvatore did you have time for looking into this?
>
> c.
>
>
>     _______________________________________________________
>
> Reply to this item at:
>
>   <http://savannah.gnu.org/bugs/?34850>
>
> _______________________________________________
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Attachment: dbleCHOL.cc
Description: Text Data

Attachment: dbleCHOL.h
Description: Text Data


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