dolfin team mailing list archive

["Garth N. Wells" <g.n.wells@xxxxxxxxxx>]

Anders Logg wrote:
> On Tue, Aug 15, 2006 at 01:38:42PM +0200, Garth N. Wells wrote:
> > Anders Logg wrote:
> > > I'd like to change the behaviour of classes LU and GMRES so that one
> > > may do
> > >
> > >     Matrix A;
> > >     Vector x, b;
> > >
> > >     GMRES::solve(A, x, b);
> > >
> > > or
> > >
> > >     GMRES::solve(A, x, b, Preconditioner::ilu);
> > >
> > > and
> > >
> > >     LU::solve(A, x, b);
> > >
> > > LU and GMRES would thus not be subclasses or typedefs of
> > > PETSc/uBlasLU/KrylovSolver but instead simple classes with static
> > > functions for simple solution of linear systems. This would then be
> > > the fast and easy way to solve a linear system. For more advanced
> > > usage, one would create a KrylovSolver or PETScKrylovSolver and then
> > > call solver.solve(). But often, one only wants to solve one linear
> > > system and not many and then it's convenient to skip the extra step of
> > > creating the solver.
> > OK with me.
>
> ok. I can fix this (if it works out with the preconditioners).
>
> > > This connects to the design of preconditioners. I think we decided to
> > > put the list of preconditioners in Preconditioner so this should be
> > > ok. What's the status of the redesign of preconditioners?
> > I don't that think we settled on the design of the preconiditoners. It 
> > would be nice to have just one enum list of preconditioners in 
> > Preconditioner.h, but I haven't had time to look at it yet.
>
> ok. Would it be enough to have a class Preconditioner which just lists
> all available preconditioners by name (ilu etc) in an enum type? And
> then the solvers just return a run-time error if the preconditioner is
> not implemented.

I was thinking more along the lines of Preconditioner being a typedef 
for PETScPreconditioner or uBlasPreconditioner. Would it work to have


   enum Preconditioner
   {
     // List of preconditioners
   }

   typedef PETScPreconidtioner Preconditioner;

Also, I wouldn't return a run-time error. It would be better to use a 
default preconditioner and print a warning message.

Garth

> /Anders
> _______________________________________________
> DOLFIN-dev mailing list
> DOLFIN-dev@xxxxxxxxxx
> http://www.fenics.org/mailman/listinfo/dolfin-dev