[Trilinos-Users] [Trilinos-Help] How to extract existing matrix rows during matrix construction

[Heroux, Michael A]

Hi John,

It is very difficult to add entries to a matrix that has already had FillComplete called.  The only exception is if you are, for example, adding a entry to column J in row I in a local submatrix for which another row, say K, already has an entry in column J. The reason for this restriction is that FillComplete computes off-processor dependencies.  If you add a new column  that is not already accounted for, the analysis done in FillComplete is no longer valid.

Is it possible to add the periodicity entries prior to calling FillComplete?

Mike


On 3/30/09 8:04 AM, "James Willenbring" <jmwille at sandia.gov> wrote:

I am forwarding this to the users list.  Please offer advice for John.

Thanks

Jim

-----Original Message-----
From: trilinos-help-bounces at software.sandia.gov
[mailto:trilinos-help-bounces at software.sandia.gov] On Behalf Of John R. Cary
Sent: Monday, March 30, 2009 7:52 AM
To: trilinos-help at software.sandia.gov
Subject: [Trilinos-Help] How to extract existing matrix rows during matrix
construction

I am trying to fill a matrix that has some periodicity
constraints.  So I start by filling in everything
in the interior.  Then for guard regions I want to do
this.

Row P is related periodically to row R, for which
the columns have been inserted, so

Find the columns (indices and values) for row R.
Put those into row P.

This works fine in serial, but it fails in parallel,
I guess because until FillComplete is called, if
row R and row P are on different processors, then the
values for row P are not known on the processor holding
row R.

I tried calling FillComplete before these "periodicity
rows" are filled, but then I get

Epetra ERROR -2, ../../../../packages/epetra/src/Epetra_CrsGraph.cpp,
line 1312

presumably at the second call to FillComplete?

Suggestions?

Thx.....John Cary

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