[petsc-dev] questions on new include organization

[Matthew Knepley]

On Wed, Feb 13, 2013 at 12:08 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
> On Feb 12, 2013, at 10:56 PM, Matthew Knepley <knepley at gmail.com> wrote:
>
> > On Tue, Feb 12, 2013 at 11:41 PM, Barry Smith <bsmith at mcs.anl.gov>
> wrote:
> >
> > 1)  Can we move the section data structures from vecimpl.h to isimpl.h?
> in preparation for its refactoring and why is PetscSectionCreate in
> section.c defined in src/vec/vec/impls/seq?   Can vsection.c be split in
> two with the only the "Vec" related routines kept in the Vec directory
> >
> > All the above makes sense if you agree with this designation as an IS.
> Can we go over this again to make sure it is correct?
> >
> > a) PetscSection does a job very similar to PetscLayout, but Layout is
> not an IS
> >
> > b) The internals of PetscSection look like two ISes, and a list of
> embedded PetscSections. This does not sound like an IS
> >
>    Regardless of these two, PetscSection does not belong in the vector
> subdirectory and most definitely not  in the impls/seq directory, so even
> if in the end it does not become exactly an IS it more belongs in the is
> directory then in the vec directory


That is convincing.


> > c) I believe the claim will be, "I can always think of the output as a
> list of integers", however that is a very broad category,
> >     which also includes graphs, meshes, etc. Internally this looks
> nothing like a list of numbers, and the current queries
> >     do not just return members of this list.
>
>    a graph and mesh most definitely cannot be thought of as a list of
> integers since they contain information about relationships BETWEEN items.
> Does PetscSection contain such additional information?
>

Yes. PetscSection represents groups of numbers, and you can see the
grouping.


>    What queries "do not just return members of this list" in PETSc
> section? (That is queries we wish to retain anyways).


For example, you can ask "how many items are in group p?". This is crucial,
and the whole point of the structure.
I don't see how you can recover that information from just the list of dof
numbers.

    Matt


>
>    Barry
>
> >
> >    Matt
> >
> >
> > 2) matimpl.h really needs vecimpl.h?
> >
> > #define __MATIMPL_H
> >
> > #include <petscmat.h>
> > #include <petsc-private/petscimpl.h>
> > #include <petsc-private/vecimpl.h>
> >
> > Doesn't seem to so I've removed the vecimpl.h and pushed
> >
> > Seems there may be a few of these unneeded dependencies hanging around,
> I'll try to hunt them down.
> >
> >    Barry
> >
> >
> >
> >
> > --
> > 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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