[Trilinos-Users] Epetra_Vector with overlap

Markus Berndt berndt at lanl.gov
Wed Jul 7 09:45:42 MDT 2010

Is it possible to set up communication schedules for an Epetra_Vector
with overlap that can be used to simply update the overlap region in
place? The documentation for Epetra_Export and Epetra_Import indicates
that one of the maps that these use to initialize communication patterns
must have GIDs that are unique. I interpret that as one of the vectors
in an Import or Export call must have no overlap at all.

To illustrate, here is an example:

x_ovl is an Epetra_Vector with overlap such that 
on PE0 it owns GIDs 0 1 2 3 4 and has a copy of 5 and 
on PE1 it owns GIDs 5 6 7 8 9 and has a copy of 4.

How do I set up a communication pattern that

- sends x_ovl(5) from PE1 to PE0 and
- sends x_ovl(4) from PE0 to PE1 

without an intermediate vector that has only the local data and no
overlap at all.

If this is not possible, what would you consider a best practices
approach to working with vectors that have overlap that avoids
unnecessary copy operations between equivalent vectors with and without


- Markus

Markus Berndt, LANL CCS-2, Mail Stop D413, 505-665-4711

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