dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Thu, Oct 20, 2011 at 11:46:58AM +0100, Garth N. Wells wrote:
> On 20 October 2011 11:28, Anders Logg <logg@xxxxxxxxx> wrote:
> > The problem was the newly added check that the preconditioner must be
> > set to "none" when a direct method is used. This wasn't checked
> > before.
> >
> > The default values have now been changed (in LinearSolver,
> > LinearVariationalSoler and NonlinearVariationalSolver) to
> >
> >  "default"
> >  "none"
> >
>
> Does this mean that a user who selects an iterative solver will, by
> default, not employ any preconditioning?

Yes.

That will be suboptimal. Perhaps we could change the values to

  default, default

but then we need to check that the backends handle "default" for
preconditioners.

Can you have a look at LinearSolver.cpp and check the logic?

--
Anders


> Garth
>
>
>
> > This will result in LU being chosen in LinearSolver.cpp.
> >
> > All the logic for this is in the constructor of LinearSolver.cpp if
> > more tuning is needed.
> >
> >
> >
> > On Thu, Oct 20, 2011 at 10:22:45AM +0100, Garth N. Wells wrote:
> >> What was the problem that has been 'fixed'?
> >>
> >> Garth
> >>
> >> ---------- Forwarded message ----------
> >> From:  <noreply@xxxxxxxxxxxxx>
> >> Date: 20 October 2011 10:11
> >> Subject: [Branch ~dolfin-core/dolfin/main] Rev 6347: Fix problem with
> >> default values for linear solver and preconditioner,
> >> To: Garth Wells <gnw20@xxxxxxxxx>
> >>
> >>
> >> ------------------------------------------------------------
> >> revno: 6347
> >> committer: Anders Logg <logg@xxxxxxxxx>
> >> branch nick: work
> >> timestamp: Thu 2011-10-20 11:09:10 +0200
> >> message:
> >>  Fix problem with default values for linear solver and preconditioner,
> >>  now set to "default" and "none".
> >> modified:
> >>  dolfin/fem/LinearVariationalSolver.h
> >>  dolfin/fem/NonlinearVariationalSolver.h
> >>  dolfin/la/LinearSolver.h
> >>
> >>
> >
> >> === modified file 'dolfin/fem/LinearVariationalSolver.h'
> >> --- dolfin/fem/LinearVariationalSolver.h      2011-06-22 10:01:17 +0000
> >> +++ dolfin/fem/LinearVariationalSolver.h      2011-10-20 09:09:10 +0000
> >> @@ -18,7 +18,7 @@
> >>  // Modified by Marie E. Rognes, 2011.
> >>  //
> >>  // First added:  2011-01-14 (2008-12-26 as VariationalProblem)
> >> -// Last changed: 2011-06-22
> >> +// Last changed: 2011-10-20
> >>
> >>  #ifndef __LINEAR_VARIATIONAL_SOLVER_H
> >>  #define __LINEAR_VARIATIONAL_SOLVER_H
> >> @@ -53,8 +53,8 @@
> >>      {
> >>        Parameters p("linear_variational_solver");
> >>
> >> -      p.add("linear_solver", "lu");
> >> -      p.add("preconditioner", "default");
> >> +      p.add("linear_solver", "default");
> >> +      p.add("preconditioner", "none");
> >>        p.add("symmetric", false);
> >>        p.add("reset_jacobian", true);
> >>
> >>
> >> === modified file 'dolfin/fem/NonlinearVariationalSolver.h'
> >> --- dolfin/fem/NonlinearVariationalSolver.h   2011-08-24 22:15:11 +0000
> >> +++ dolfin/fem/NonlinearVariationalSolver.h   2011-10-20 09:09:10 +0000
> >> @@ -18,7 +18,7 @@
> >>  // Modified by Marie E. Rognes, 2011.
> >>  //
> >>  // First added:  2011-01-14 (2008-12-26 as VariationalProblem.h)
> >> -// Last changed: 2011-06-22
> >> +// Last changed: 2011-10-20
> >>
> >>  #ifndef __NONLINEAR_VARIATIONAL_SOLVER_H
> >>  #define __NONLINEAR_VARIATIONAL_SOLVER_H
> >> @@ -57,8 +57,8 @@
> >>      {
> >>        Parameters p("nonlinear_variational_solver");
> >>
> >> -      p.add("linear_solver",  "lu");
> >> -      p.add("preconditioner", "default");
> >> +      p.add("linear_solver",  "default");
> >> +      p.add("preconditioner", "none");
> >>        p.add("symmetric", false);
> >>        p.add("reset_jacobian", true);
> >>
> >>
> >> === modified file 'dolfin/la/LinearSolver.h'
> >> --- dolfin/la/LinearSolver.h  2011-10-07 12:24:30 +0000
> >> +++ dolfin/la/LinearSolver.h  2011-10-20 09:09:10 +0000
> >> @@ -44,8 +44,8 @@
> >>    public:
> >>
> >>      /// Create linear solver
> >> -    LinearSolver(std::string method = "lu",
> >> -                 std::string preconditioner = "ilu");
> >> +    LinearSolver(std::string method = "default",
> >> +                 std::string preconditioner = "none");
> >>
> >>      /// Destructor
> >>      ~LinearSolver();
> >>
> >
> >> _______________________________________________
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> >
> >