dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Tue, Aug 15, 2006 at 02:16:52PM +0200, Garth N. Wells wrote:
> 
> 
> Anders Logg wrote:
> > On Tue, Aug 15, 2006 at 01:54:02PM +0200, Garth N. Wells wrote:
> >>
> >> 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;
> > 
> > Don't think that would work. Preconditioner can't be both an enum type
> > and a class. We could do something like putting the list of
> > preconditioners in a separate file named DefaultPreconditioners.h and
> > then #include it inside the class definition of both
> > PETScPreconditioner and uBlasPreconditioner. Then we do the typedef as
> > above and it would look like we have Preconditioner::ilu etc:
> > 
> > DefaultPreconditioners.h:
> > 
> > #ifndef, namespace dolfin etc
> > 
> > enum DefaultPreconditioners{
> > {
> >     none,
> >     ilu
> >     ...
> > }
> > 
> > PETScPreconditioner.h:
> > 
> > #ifndef, namespace dolfin etc
> > 
> > class PETScPreconditioner
> > {
> > public:
> > 
> > #include <dolfin/DefaultPreconditioners.h>
> > 
> >     ...
> > 
> > }
> > 
> > Same in uBlasPreconditioner. Would that work?
> >
> 
> Sounds good. Not sure what the best name is though. Go ahead and add it. 
> I can make changes later to ensure that the chosen preconditioner is 
> actually selected and applied.

ok, I'll see what I can do.

/Anders

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