dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Thu, May 15, 2008 at 05:24:39PM +0100, Nuno David Lopes wrote:
> After a great struggle for a clean install in a ubuntu 8.04 box i could 
> compile dolfin, with umfpack and without petsc. Just like i have in my   
> ubuntu 7.10 laptop.
> 
> After some tests i've found that I'm unable to get a KrylovSolver other than 
> Bicgstag!!!! Is this a Known issue? I guess i've all the blas
> related libs...

Yes, I think someone else mentioned it to me.

See if it works now. I've attempted to fix it. If not, it should be
easy to fix.



> libboost 
> atlas3 
> lapack3 
> refblas3 
> with dev's also.
> 
> if i have something like:
> 
> KrylovSolver solver(gmres,ilu); 
> 
> KrylovSolver solver(cg); 
> 
> LinearSolver solver(gmres);
> 
> solve(A,x,b,gmres);
> 
> i got the following message
> 
> Solving linear system of size 40121 x 40121 (uBlas Krylov solver).
> *** Warning: Requested Krylov method unknown. Using BiCGStab.
> 
> I've no problems with LUSolver.(umfpack seems to be alright)
> 
> Is this a Known issue?
> Do i need petsc for that?
> I can't compile with umfpack and petsc...
> but as i've seen thru the mailing list that is known and difficult issue
> about package dependencies, right?
> 
> Thanks.
> 
> 
> On Saturday 10 May 2008, Anders Logg wrote:
> > LinearSolver is now a general wrapper for all linear solvers
> > (rather than a base class for linear solvers). Creating a LinearSolver
> > and reusing it instead of calling solve() multiple times gives
> > about 5% speedup.
> >
> > It's a subclass of Parametrized, meaning that it's possible to set
> > parameters. For example, it should be possible to do
> >
> >   LinearSolver solver(gmres, amg);
> >   solver.set("Krylov relative tolerance", 1e-6);
> >   solver.set("Krylov absolute tolerance". 1e-6);
> >   solver.solve(A, x, b);
> >
> > and have those parameters passed on to the backend (for example
> > PETSc).
> >
> > For those of you interested in setting special parameters to different
> > backends, the available parameters are listed in
> >
> >   dolfin/parameter/DefaultParameters.h
> >
> > and they are accessed in the different backends by for example
> >
> >   tol = get("Krylov relative tolerance");
> >
> > Supply a patch if there are parameters you think are missing.
> >
> > We probably should not support all parameters for all backends.
> 
> 
>