changes to MatSetOption() in petsc-dev

[Lisandro Dalcin]

On 7/9/07, Barry Smith <bsmith at mcs.anl.gov> wrote:
> > Not sure what to do with  MAT_USE_INODE. Perhpas it can be
>
>    Can just leave it as an on-off switch as it is now

It's OK for me anyway.

> > * You removed the MAT_[ROW|COLUMN]_SORTED stuff. I think you should
> > keep it, even when this feature is not yet implemented.
>
>   It is not a mater of being implemented, it used to be used but is not
> needed IMHO. What do you think it would be used for?

Well, I believe that if the user can assert that the row or cols
indices are sorted, then the matrix assembly for row/column compressed
formats can be implemented faster by reducing the range where you have
to do binary search for locating the index. Is this correct? I said I
was not implemented because some time ago I've looked at matrix
assembly routines for AIJ and I understood this optimitzation was not
implemented despite the option MAT_[ROW|COLUMN]_SORTED was available.

This option could be used for a power user to inform PETSc that the
row or column indices in MatSetValues() are sorted. However, I have to
recognize that it use is error prone. This can interact really badly
with MatSetValuesLocal. Perhaps it's a good idea to remove it anyway.



-- 
Lisandro Dalcín
---------------
Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
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