Hello Martin, I started by modifying step-33 which was using trilinos solvers. I dont really need to use trilinos at present.
So my best options would be to use dealii::SolverGMRES with dealii::PreconditionBlockSSOR. Thanks praveen On Fri, Mar 25, 2011 at 9:48 PM, Martin Kronbichler < [email protected]> wrote: > Dear Praveen, > > > > For steady state problems, it is recommended to use a block SSOR > > preconditioner. This seems to correspond to the AZ_precond = AZ_sym_GS > > option in aztec. Am I right ? > > > > > > But if I use this option, I get an error that > > > > > > "sym GS preconditioning can only be used with MSR matrices" > > The error message basically tells you that you can't use the Aztec > preconditioners in conjunction with the matrix format used in > TrilinosWrappers::SparseMatrix, which is of type Epetra_CrsMatrix. What > you could do is to use a TrilinosWrappers::SolverGMRES object and give > it a TrilinosWrappers::SparseMatrix and > TrilinosWrappers::PreconditionSSOR. That should work I think. But then > you're still using a point-by-point SSOR and not a _block_ SSOR, for > which you would need to invert some diagonal blocks. For that we do > currently not have any wrapper classes to Trilinos, and the only option > would be PreconditionBlock with deal.II sparse matrices. What is the > motivation for using Trilinos matrices? Do you plan to run your program > in parallel? If not, you can use deal.II matrices just fine with block > SSOR. > >
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