[Trilinos-Users] Using the EpetraExt_CrsGraph_MapColoring class

[Bernsen, E.]

Hi Erik,

Thanks for the very quick response! I'm trying to color an assymetric matrix. The sparsity pattern of the matrix is easily extended to be symmetric. For me it's important that the coloring can be used by the FiniteDifferenceColoring class to construct a Jacobian matrix and I don't think that's the case of assymetric matrices (even if the sparsity pattern is symmetric). 

In the user guide I read that for non-symmetric problems hypergraph partitioning is recommended. Is support for this in Isorropia available? Or is there any other method you can suggest for coloring assymetric matrices?

Regards,
Erik


-----Original Message-----
From: trilinos-users-bounces at software.sandia.gov on behalf of Erik Boman
Sent: Mon 4/13/2009 5:47 PM
To: Bernsen, E.
Cc: trilinos-users at software.sandia.gov
Subject: Re: [Trilinos-Users] Using the EpetraExt_CrsGraph_MapColoring class
 
Hi Erik,

I'm not sure about your specific question, but you should know that the
more recent work on coloring has been moved to the Zoltan and Isorropia
packages. Take a look at Isorropia::Epetra::Colorer at
http://trilinos.sandia.gov/packages/docs/r9.0/packages/isorropia/doc/html/classIsorropia_1_1Epetra_1_1Colorer.html

This package uses a more scalable parallel algorithm, so you may want to
try it. One drawback is that the current version is limited to
structurally symmetric matrices. We plan to support nonsymmetric
matrices in the next release.

Regards,
Erik 


On Mon, 2009-04-13 at 09:24 -0600, Bernsen, E. wrote:
> 
> Hello,
> 
> I'm trying to use the EpetraExt_CrsGraph_MapColoring class to color
> the independent columns of a graph and then use the
> FiniteDifferenceColoring class to construct a Jacobian matrix.
> Sometimes the coloring algorithms give unexpected results. For
> instance consider the attached program (test.C) which creates a 2x2
> triangular matrix and then colors the corresponding graph. I think the
> coloring of this matrix should result in two colors. However according
> to the output of the program (out.txt) only one color is required. The
> program was run on a single processor in this case.
> 
> When using the GREEDY algorithm instead of JONES_PLASSMEN the coloring
> seems to work allright as long as the program is run on a single
> processor. If more than one processor is used results seem to be also
> incorrect.
> 
> Is there a bug in the EpetraExt_CrsGraph_MapColoring class or is the
> use of this class in test.C incorrect?
> 
> Regards,
> 
> Erik Bernsen
> 
> 
> 
> 

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