dolfin team mailing list archive

[Nuno David Lopes <ndl@xxxxxxxxxxxxxx>]

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...
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.



-- 
Nuno David Lopes

e-mail:ndl@xxxxxxxxxxxxxx        (FCUL/CMAF)
           nlopes@xxxxxxxxxxxxxxx    (ISEL)
http://ptmat.ptmat.fc.ul.pt/%7Endl/