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Re: changes to MatSetOption() in petsc-dev
On 7/9/07, Barry Smith <bsmith@xxxxxxxxxxx> 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)
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
PTLC - Güemes 3450, (3000) Santa Fe, Argentina
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