[Trilinos-Users] EpetraExt::CrsGraph_Transpose

[Heroux, Mike]

Luca,

There is a more general version of this functionality in Epetra, in the class Trilinos/packages/epetra/src/Epetra_RowMatrixTransposer.[h,cpp].  Although the Epetra version also transposes values, it is easily modified to work only with the graph, if that is what you really need.

This version also accepts a general Epetra_RowMatrix object, but specializes for the case where original matrix is itself an Epetra_CrsMatrix (making it more efficient).  It also has a values update mode that is very handy.

If you need the graph version and have trouble making the conversion, let me know.

Mike

From: <Bertagna>, Luca <lbertag at emory.edu<mailto:lbertag at emory.edu>>
Date: Monday, May 19, 2014 2:55 PM
To: "trilinos-users at software.sandia.gov<mailto:trilinos-users at software.sandia.gov>" <trilinos-users at software.sandia.gov<mailto:trilinos-users at software.sandia.gov>>
Subject: [Trilinos-Users] EpetraExt::CrsGraph_Transpose


Dear all,

I was trying to use the class CrsGraph_Transpose in EpetraExt to get the graph of the transpose of a NON-SQUARE matrix and I noticed that it would not work. In particular, it looks like the class assumes that the matrix is square. I was wondering if that's a design choice or just something that happened but not intended. In particular, I think the class would still work the same if you replace the occurrences of RowMap (which is the row map of the given graph) at lines 103-104 and 133 (only the first occurrence of RowMap) in file EpetraExt_Transpose_CrsGraph.cpp with graph.DomainMap().

Am I correct? If not, can you explain why this would not work for non-square matrices?

Thanks


Luca Bertagna
Math&CS, Emory University, Atlanta
www.mathcs.emory.edu/~lbertag