[Trilinos-Users] Using the EpetraExt_CrsGraph_MapColoring class

[Bernsen, E.]

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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