[dune-fem] Preconditioning CGInverseOperator

[Tobias Malkmus]

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Hi Marco

You can use the PreconditionedInverseOperator< Preconditioner,
InverseOperator > for this.
The Preconditioner needs to be derived from Dune::Fem::Operator< ... >.
It should work with CGInverseOperator< ... > and
ParDGGeneralizedMinResInverseOperator< ... > as the InverseOperator.

As far as i know the OEM solvers needs to get a 'systemMatrix' and a
'preconditionedMatrix' from the LinearOperator. You can write a
wrapper class which implements the calls to the 'systemMatrix' by
applying the matrix-free operator. Within this wrapper a call to the
'preconditionedMatrix' needs to be implemented. Have a look into the
file dune-fem/dune/fem/solver/oemsolver/oemsolver.hh.


Best Tobias

On 10/07/2014 11:52 AM, Agnese, Marco wrote:
> Hi, I have a question about preconditioning a 
> Dune::Fem::Solver::CGInverseOperator. The matrix of the system is 
> not assembled. I would like to build and use a preconditioner
> which is not assembled. Is it possible? Because, reading the 
> documentation, it seems that the preconditioner must be assembled 
> and diagonal. Am I wrong?
> 
> Moreover, if I wanted to use an OEM solver in the same setting (no 
> assembled operator and no assembled preconditioner), would it be 
> possible to do that? Cheers, Marco. 
> _______________________________________________ dune-fem mailing 
> list dune-fem at dune-project.org 
> http://lists.dune-project.org/mailman/listinfo/dune-fem
> 
> 


- -- 
Tobias Malkmus                 <tomalk at mathematik.uni-freiburg.de>

Mathematisches Institut               Tel: +49 761 203 5627
Abt. für Angewandte Mathematik        Universität Freiburg
Hermann-Herder-Str. 10
79104 Freiburg

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