[Trilinos-Users] Epetra Vectors/Maps

John Mitchell jamitch at sandia.gov
Fri Jan 29 16:55:50 MST 2010

Thanks Alan and Mike.

The reason I was asking is because the documentation says:

    \param In
            NumGlobalElements - Number of elements to distribute.  Must be
     either -1 or equal to the computed sum of NumMyElements across all
     processors in the Epetra_Comm communicator.

This documentation must not be correct or I'm reading it the wrong way?


Williams, Alan B wrote:
> Hi John,
> Yes you can have vectors/maps that overlap in the way that you describe. We have finite-element codes that use epetra in exactly that way.
> Alan
>> -----Original Message-----
>> From: trilinos-users-bounces at software.sandia.gov [mailto:trilinos-
>> users-bounces at software.sandia.gov] On Behalf Of John Mitchell
>> Sent: Friday, January 29, 2010 4:38 PM
>> To: trilinos-users at software.sandia.gov
>> Subject: [Trilinos-Users] Epetra Vectors/Maps
>> I am new to the use of Epetra and have a couple basic questions that
>> don't appear to be directly addressed in the tutorial.
>> Is it possible to create an
>> Epetra_Map(numGlobalElements,numMyElements,myElements,0,comm)
>> where sum(numMyElements) over all processors != numGlobalElements?
>> What I have, is a list of ids that I own, and then a list of ids that I
>> share but don't own.  I need to do parallel calculations and assemblies
>> on a vector that is of length numOwned+numShared.  Assembly operations
>> for both owned and shared may require off-processor communications.  I
>> have a vector f = {f_owned, f_shared}; If a point that is owned on
>> processor is shared on another processor, then the assembly of f_owned
>> will require contributions f_shared from the sharing off processor
>> I was planning on using the above Epetra_Map as a target map for
>> creating an Epetra_Import -- does that make sense?
>> Thanks,
>> John
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