[Trilinos-Users] Epetra Matrices for ML from Metis Partitioned Matrices

[gjl7 at et.byu.edu]

As for using Epetra_RowMatrix derived objects, since the the matrices are
already set up in a compressed sparse row format, it is easy to create and
use Epetra_CrsMatrix objects.

However, after looking at the online development documentation of the
Epetra_FECrsMatrix, I'm not seeing how to "unify" the rows corresponging
to boundary nodes.  Is that the correct location and I'm just not seeing
it or is there a better place to look?

Greg


> Hi Greg,
>
> the ML preconditioning class works with Epetra_RowMatrix derived objects.
> It
> requires that each row is *entirely* owned by exactly one processor. If
> you
> can reproduce this situation, it is quite easy to wrap your distributed
> matrix format as an Epetra_RowMatrix, then call ML. The ML user's guide
> describes how local and global indices are managed by ML.
>
> If you partition the grid elements, then probably you first need to
> "unify"
> the rows corresponding to boundary nodes, then call ML. Classes like
> Epetra_FECrsMatrix can make this step easy.
>
> -Marzio
>
>
> On 5/10/06, gjl7 at et.byu.edu <gjl7 at et.byu.edu> wrote:
>>
>> We are linking Trilinos with another code.  The finite element mesh has
>> already been partitioned using metis and the local matrices are already
>> set up in a compressed sparse row format and distributed on each
>> processor.  Now, we want to use ML to solve these matrices, with ML
>> realizing these matrices are coupled due to node overlap.  Is there an
>> example showing how to set up the Epetra matrices so ML realizes these
>> matrices are linked by the overlapping nodes?  If there is no documented
>> example, what would you recommend?  Thanks.
>>
>> Greg Larson
>>
>>
>>
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>