[petsc-users] Using edge-weights for partitioning

[Eda Oktay]

Hi all,

I am trying to partition a sparse matrix by using ParMETIS. I am converting
my matrix to adjacency type and then applying partitioning. Default, I
understood that partitioning doesn't use edge-weights. However, when I used
the following codes I saw from ex15 and used "-test_use_edge_weights 1", I
am getting the same results as when I don't consider edge weights.

PetscBool use_edge_weights=PETSC_FALSE;

PetscOptionsGetBool(NULL,NULL,"-test_use_edge_weights",&use_edge_weights,NULL);
  if (use_edge_weights) {
      MatPartitioningSetUseEdgeWeights(part,use_edge_weights);

      MatPartitioningGetUseEdgeWeights(part,&use_edge_weights);
      if (!use_edge_weights) SETERRQ(PETSC_COMM_SELF,PETSC_ERR_ARG_INCOMP,
"use_edge_weights flag does not setup correctly \n");
    }

My matrix does not consist of 1s and 0s, so I want partitioning to consider
all the nonzero elements in the matrix as edge weights. Don't
MatPartitioningSetUseEdgeWeights and MatPartitioningGetUseEdgeWeights do
that? Should I add something more? In the page
of MatPartitioningSetUseEdgeWeights, it is written that "If set
use_edge_weights to TRUE, users need to make sure legal edge weights are
stored in an ADJ matrix.". How can I make sure of this?

I am trying to compare the use of ParMETIS with the spectral partitioning
algorithm when I used a weighted Laplacian.

Thanks!

Eda
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