[petsc-dev] Dense matrices

[Matthew Knepley]

So for dense matrices, we assume column alignment when we pass in the
pointer? That is
probably what was wrong. Crap it does say this at the top, but not at the
argument. I will
augment the documentation.

  Matt

On Sun, Jan 17, 2010 at 10:42 AM, Jed Brown <jed at 59a2.org> wrote:

> On Fri, 15 Jan 2010 09:58:46 -0600, Matthew Knepley <knepley at gmail.com>
> wrote:
> > SeqDense MatMult was inexplicably giving me the wrong answers. I
> > checked the BLAS call (and the underlying defines) and they also
> > looked right to me. I temporarily checked in the simple-minded loops
> > which do give me the correct answer.
>
> The matrices are column-aligned.  The "simple-minded loops" you checked
> in (cc0b86d7fd3f) assume row-aligned matrices, and are thus delivering
> the wrong results for everyone that assembled their matrix correctly, so
> I'm reverting that change.
>
> How were you assembling this matrix?
>
> Jed
>



-- 
What most experimenters take for granted before they begin their experiments
is infinitely more interesting than any results to which their experiments
lead.
-- Norbert Wiener
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