[Trilinos-Users] reading nonlocal entries of a Epetra_FECrsMatrix ?? possible ?

Michael A Heroux maherou at sandia.gov
Wed Dec 19 21:45:58 MST 2007

Epetra provide import and export capabilities to replicate data from other
processors.  If you need specific rows of a matrix on a particular
processor, you can form an Epetra_Map (call it importMap) containing the
global IDs of rows you need, then create an Epetra_Import object using
importMap as the targetMap and the rowMap of your matrix as the sourceMap.
Then create a new matrix (call it importMatrix) with importMap as the
rowMap.  Finally, perform the import and do FillComplete

Here is a code sketch (not guaranteed to be perfect, but close)

 Create STL int vector called importGIDs with global IDs of rows you need.


 Epetra_Map importMap(-1, &importGIDs[0], 0, comm);
 Epetra_Import importer(importMap, matrix.RowMap());
 Epetra_CrsMatrix importMatrix(Copy, importMap, 0);
 importMatrix.Import(matrix, importer, Add);

At this point, importMatrix has the rows you specified in the importGIDs


On 12/19/07 9:57 PM, "Davood Ansari" <david.ansari at gmail.com> wrote:

> Hi every one
> Epetra_FECrsMatrix if wonderful for FE applications.
> Building some kinds of FE matrices requires some post processing.
> During the post processing I need to read the values stored in some entries
> of my FECrsMatrix that are not local. How is that possible ?
> Yours
> Davood
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> Trilinos-Users at software.sandia.gov
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