[Dune] On-the-fly CG operator in ISTL

Tobias Malkmus tomalk at mathematik.uni-freiburg.de
Wed Sep 24 08:49:08 CEST 2014


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Hi Andrea

The cg implementation and some other solvers expect that your linear
operator can be cast into LinearOperator<X,Y> (see
dune-istl/dune/istl/operators.hh). X and Y are the types of the rhs
and solution vectors.

You will have to derive your linear on-the fly operator from this
class to do so. Within this interface class the following methods are
pure and need to be implemented in derived classes:
void apply (const X& x, Y& y) const
void applyscaleadd (field_type alpha, const X& x, Y& y) const

Best Tobias


On 09/24/2014 12:24 AM, Sacconi, Andrea wrote:
> Hi DUNErs,
> 
> I have a very quick question: I have a symmetric operator which
> does not have its matrix counterpart, since it is not assembled. I
> need to invert it with an on-the-fly CG solver; what should I use
> from ISTL classes? Naturally, rhs and solution vectors have been
> declared as BlockVector 's.
> 
> Thanks in advance! Andrea 
> __________________________________________________________
> 
> Andrea Sacconi PhD student, Applied Mathematics AMMP Section,
> Department of Mathematics, Imperial College London, London SW7 2AZ,
> UK a.sacconi11 at imperial.ac.uk
> 
> _______________________________________________ Dune mailing list 
> Dune at dune-project.org 
> http://lists.dune-project.org/mailman/listinfo/dune
> 


- -- 
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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