[petsc-dev] who broke petsc-dev

[Matthew Knepley]

On Sun, Nov 13, 2011 at 10:52 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>   The simplest fix is to only do this null space business if Amat exists.
>

I did this.


>   But keep in mind that KSP and SNES now have two modes of operation, the
> second uses the DM to provide many of the items they need at setup time.
> This is different then the classic KSP and SNES where the only way to do
> things were with KSPSetOperators() and SNESSetFunction/Jacobian. This is
> why Jed is indicating that it may be too soon at this stage to muck with
> the null space business.


This is bad. Things are becoming unacceptably complicated. I can't trust
that obvious arguments are in this function,
and I can't trust that setup will be called since the logic is convoluted.
This needs to be rethought.

   Matt


>
>   Barry
>
>
> On Nov 13, 2011, at 4:47 PM, Matthew Knepley wrote:
>
> > On Sun, Nov 13, 2011 at 10:47 PM, Barry Smith <bsmith at mcs.anl.gov>
> wrote:
> >
> > On Nov 13, 2011, at 4:45 PM, Matthew Knepley wrote:
> >
> > > On Sun, Nov 13, 2011 at 10:44 PM, Jed Brown <jedbrown at mcs.anl.gov>
> wrote:
> > > On Sun, Nov 13, 2011 at 16:36, Barry Smith <bsmith at mcs.anl.gov> wrote:
> > > 1) It is legitimate to call KSPSetOperators with a null Amat so this
> is a bug that crashes large parts of PETSc
> > >
> > > This logic should be moved much later (like to KSPSetUp()).
> > >
> > > I disagree, since SetOperators() is where we know that the matrix is
> changing.
> >
> >  Yes, but the matrix may not exist.
> >
> > I have no problem fixing this, but what does that mean? I can't fix it
> until I understand what you are doing here.
> >
> >   Matt
> >
> > >
> > >    Matt
> > >
> > >
> > >
> > > 2) Do you really want to do this? I am not sure I like it.
> > >
> > > I think that attaching the null space to the Mat should be the
> preferred way to communicate it, especially in the case of a deeply nested
> hierarchy.
> > >
> > >
> > >
> > > --
> > > 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
> >
> >
> >
> >
> > --
> > 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
>
>


-- 
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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