[Trilinos-Users] Trouble With ReplaceGlobalValues (1, &global_row, nnz, Indices, &zeros_A, Epetra_FECrsMatrix::ROW_MAJOR) ;

Williams, Alan B william at sandia.gov
Mon Mar 17 14:00:12 MDT 2008

Perhaps the trouble you're seeing relates to whether the matrix row is local or not.
A FECrsMatrix has a Epetra_Map (the row-map) which describes a non-overlapping assignment of rows.
Sometimes there is some confusion between some of the *GlobalValues methods on FECrsMatrix versus similarly named methods on the base CrsMatrix class. If you're calling the one on the CrsMatrix class, then it won't handle off-processor rows correctly.


From: trilinos-users-bounces at software.sandia.gov [mailto:trilinos-users-bounces at software.sandia.gov] On Behalf Of Davood Ansari
Sent: Saturday, March 15, 2008 11:30 AM
To: trilinos-users at software.sandia.gov
Subject: [Trilinos-Users] Trouble With ReplaceGlobalValues (1, &global_row, nnz, Indices, &zeros_A, Epetra_FECrsMatrix::ROW_MAJOR) ;

Hi everyone

I have a ready made and GlobalAssembled FECrs_Matrix

In later stages of my code I am trying to modify the matrix entries using
ReplaceGlobalValues (1, &global_row, nnz, Indices, &zeros_A, Epetra_FECrsMatrix::ROW_MAJOR) ; // basically I am replacing a row with a new one -- a dense vector
ReplaceGlobalValues (nnz, Indices, 1, &global_row, &zeros_A, Epetra_FECrsMatrix::COLUMN_MAJOR) ; // basically I am replacing a column with a new one -- a dense vector
Of course, I expect the method to replace some entries with new values (and I may have multiple replacements over
the same entry but their order in not important). What happens is that for certain entries the method
adds the required new value with the old one and does not enforce any modification to some other entries.
Unlike the replace method SumIntoGlobalValues works fine with all on.off-process entries.

I am really lost and have tried out any thing that I could think of.
Does anybody know where possibly I should look for the problem ?


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