[petsc-users] MatCreateMPIAIJWithSplitArrays for symmetric matrix?

[Jed Brown]

On Mon, Nov 8, 2010 at 12:14, Daniel Langr <daniel.langr at gmail.com> wrote:

> MatCreateMPISBAIJWithArrays() copy the arrays, so it won't help me. I need
> all available memory for a matrix, so I cannot have it in memory twice.
>

What preconditioners do you use?  Block Jacobi with incomplete
factorization, for example, uses the same amount of memory as the matrix,
presumably you could free those arrays before factoring.  This doesn't help
if you use SOR.

Matrices emerge in new methods in nuclear structure computations
> (symmetry-adapted no-core shell models). I don't know how to allocate arrays
> exactly.
>

Where does the sparsity of the matrix come from?


> But, I can generate a matrix into CSR format and then probably reorganize
> it (split into diagonal and off-diagonal entries).
>

It's not clear how you could generate it in CSR format to begin with,
considering that if you underallocate, you will be forced to reallocate and
copy.  It would be possible to have a MatCreateMPISBAIJWithSplitArrays, but
it would be very peculiar to be able to create the arrays without being able
to preallocate correctly.

Jed
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20101108/7d2523de/attachment.htm>