[Dune] Applying an ISTL InverseOperator to multiple right-hand sides

[Bård Skaflestad]

> Hi Bård!
> 
> Assembling the matrix once and then solving for all rhs at once (e.g.
> with a BCRSMatrix<ScaledIdMatrix>) may(!) still be faster, because you
> get a better cache usage.

Hi Oliver,

The ScaledIdentityMatrix is indeed a possible solution.  I'll
investigate its performance characteristics in my case.  Unfortunately
it is almost entirely undocumented (and doesn't show up amongst the
classes referenced from the ISTL Matrix documentation), but reading the
code clearly shows that the ScaledIdentityMatrix wraps a single scalar
and implements the various operations in terms of this scalar.

Thank you for your suggestion,
-- 
Bård Skaflestad                            <Bard.Skaflestad at sintef.no>
SINTEF ICT, Applied mathematics