Defining my own reordering method for ILU

[Laslo Tibor Diosady]

Hi,

I want to be able to define an ordering type for the ILU factorization
to be used as a preconditioner to GMRES. I have successfully used
PCFactorSetMatOrdering(), to set standard types, however I have my own
reordering method which I would like to be able to use.

Since my reordering method is based on information not found within the
matrix and I may want to solve several different systems with the same
ordering, what I really want to be able to do is create an index set in
advance and pass it is to be used for the reordering.

Is this possible, and how would you suggest I go about doing this?

Thanks,

Laslo