[Trilinos-Users] Problem inserting non-local data in Epetra_FECrsMatrix

[erhan turan]

Hello,

I had a similar problem before. My colleague Cyril Flaig found a
workaround. For non-local entries, you can try SumIntoGlobalValues rather
than InsertGlobalValues. I mean, If A.LRID()== -1 , use SumIntoGlobalValues
with global row index and use InsertGlobalValues otherwise. That might
work.

For that purpose, what is defined was two pointers say AF and A using
Epetra_FECrsMatrix and Epetra_CrsMatrix, respectively. Here, we first
declared AF using the map and later just saying A=AF. Later all methods are
used for A: A->InsertGlobalValues() and A->SumIntoGlobalValues() . Fill is
completed using AF->GlobalAssemble(). If you try, A->FillComplete() it wont
fill non-local entries. That might be not the best solution. Maybe there is
a simpler way. But it will probably work.

Since you mentioned this issue, I want to make a reference to
Epetra_FECrsMatrix documentation. There it reads:

InsertGlobalValues()<http://trilinos.sandia.gov/packages/docs/r10.8/packages/epetra/doc/html/classEpetra__FECrsMatrix.html#a54820e91fb84c7c594c4e6f3ea290fe4>
inserts
values into the matrix only if the graph has not yet been finalized (
FillComplete()<http://trilinos.sandia.gov/packages/docs/r10.8/packages/epetra/doc/html/classEpetra__CrsMatrix.html#a355b4e8d1e28b16bacf37ab637ac0c3f>
has
not yet been called). For non-local values, the call to
InsertGlobalValues()<http://trilinos.sandia.gov/packages/docs/r10.8/packages/epetra/doc/html/classEpetra__FECrsMatrix.html#a54820e91fb84c7c594c4e6f3ea290fe4>
 *may succeed *but
theGlobalAssemble()<http://trilinos.sandia.gov/packages/docs/r10.8/packages/epetra/doc/html/classEpetra__FECrsMatrix.html#aca5191dcdfb99eb6316b86fee459b243>
method
*may then fail* because the non-local data is not actually inserted in the
underlying matrix until
GlobalAssemble()<http://trilinos.sandia.gov/packages/docs/r10.8/packages/epetra/doc/html/classEpetra__FECrsMatrix.html#aca5191dcdfb99eb6316b86fee459b243>
is
called.

This might be the reason that FillComplete() alone does not work but those
overloaded SumInto methods over GlobalAssemble() work. However I still
believe that this sentence *may be* vague :)

Erhan Turan
Department of Computer Science
ETH Zurich


On Wed, Feb 15, 2012 at 4:19 PM, Eric Marttila <
eric.marttila at thermoanalytics.com> wrote:

> Dear all,
>
> I've been using Epetra_CrsMatrix to store a linear system, but recently
> encountered a situation where I need to fill the entire matrix from the
> master
> process.  From reading the Epetra documentation I believe I need to switch
> to
> a EpetraFECrs_Matrix to do this.
>
> I changed my code to use the EpetraFECrs_Matrix, but my call to
> InsertGlobalValues() fails on the first row of the matrix that is
> non-local to
> the master process.
>
> I've attached a small section of code that reproduces the behavior.  It
> runs
> fine with 1 process, but fails when inserting row index 2 when run with 2
> processors.
>
> I would appreciate any thoughts on what I'm missing with my usage of
> EpetraFECrs_Matrix.
>
> Thanks.
> --Eric
>
> p.s. I'm running Trilinos 10.8.5 on linux x86_64, using mpich2.
>
> --
> Eric A. Marttila
> ThermoAnalytics, Inc.
> 23440 Airpark Blvd.
> Calumet, MI 49913
>
> email: Eric.Marttila at ThermoAnalytics.com
> phone: 810-636-2443
> fax:   906-482-9755
> web: http://www.thermoanalytics.com
>
> _______________________________________________
> Trilinos-Users mailing list
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> http://software.sandia.gov/mailman/listinfo/trilinos-users
>
>
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