Additional operations for MATSBAIJ

[Dave May]

Hi Hong,
    Thanks for your feedback.

Dave

On Wed, Mar 5, 2008 at 5:08 AM, Hong Zhang <hzhang at mcs.anl.gov> wrote:

>
> Dave,
>
> >    I would like to inquire whether there are plans to add some MatMatXXX
> > support (in particular MatPtAP) for the MATSBAIJ types in the next
> version
> > of petsc?
>
> No, we do not have plan. It is more than few hours work to write
> MatPtAP_SBAIJ(), parallel version requires much more time.
>
> >
> > The code used in our group combines the FEM with a PIC scheme. The
> addition
> > of the particles increase the memory usage significantly, thus we could
> > really benefit from the memory saved by only storing the upper
> triangular
> > part of our global stiffness matrix. The FEM part of the code utilizes
> > multigrid with Galerkin coarse grid operators constructed via MatPtAP.
>
> Although SBAIJ matrix saves half memory of SPARSE matrices,
> you pay price for data accessing and complecated data communication.
> You may use petsc aij matrix with all the functional support, but
> call symmetric solvers/preconditioners, e.g., cholesky or icc
> which save half of memory for factored matrices (would be significant
> in many cases).
>
> Hong
>
>
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