Hi Derek,
Attached is another small Trilinos patch. Essentially, it sets the
various Aztec/NOX parameters to the same values as the PETSc solver does.
Additionally, there seems to be an inconsistency in Trilinos regarding
the size of the Krylov subspace. The docs state the default value is 30
(as in PETSc), whereas the code has it set to 300. I'm no expert but
this seems way too large, at least for the problems I'm dealing with,
and results in Aztec convergence problems. Setting it to 30 produces
identical results in PETSc and Trilinos (by identical I mean identical
residuals at every linear iteration).
-Norbert
Derek Gaston wrote:
> On Oct 15, 2008, at 2:33 AM, Norbert Stoop wrote:
>
> Parallel is where the issue is... and is why I haven't enabled that
> capability yet. I haven't yet done the work to make EpetraMatrix work
> in parallel like I did for EpetraVector.
>
> But if you have it working in serial... by all means send a patch.
>
>> I understand that Trilinos support is unofficial and work in progress. I
>> am still new to libmesh, and Trilinos in particular, but will invest
>> some more hours into this problem. Not sure if that will be of any help,
>> though...
>
> Any help is appreciated... I'm currently being pulled in about 7
> different directions.... so even if small progress is being made in this
> direction... that will be better than none.
>
>> What puzzles me is that the error is already fully present after the
>> first nonlinear iteration, ie. after solving the linearized system.
>
> Yes... if there is a problem in parallel then you probably aren't
> getting the correct summations of off-processor contributions when you
> do a residual evaluation.... so you would see it _immediately_. Your
> very first residual evaluation would be wrong.
>
> Like I say though.... that shouldn't be broken anymore (for pure matrix
> free). Are you sure you've updated your libMesh? There was a small bug
> where closing the EpetraVector was not calling GlobalAssemble... but I
> think I committed the fix for that a little bit ago.
>
> Derek
>
Index: trilinos_nox_nonlinear_solver.C
===================================================================
--- trilinos_nox_nonlinear_solver.C (revision 3121)
+++ trilinos_nox_nonlinear_solver.C (working copy)
@@ -201,9 +201,10 @@
Teuchos::ParameterList& lsParams = newtonParams.sublist("Linear Solver");
lsParams.set("Aztec Solver", "GMRES");
- lsParams.set("Max Iterations", 800);
- lsParams.set("Tolerance", 1e-10);
+ lsParams.set("Max Iterations",
static_cast<int>(this->max_linear_iterations));
+ lsParams.set("Tolerance", this->initial_linear_tolerance);
lsParams.set("Output Frequency", 1);
+ lsParams.set("Size of Krylov Subspace", 30);
// lsParams.set("Preconditioner", "AztecOO");
Teuchos::RCP<NOX::Epetra::Interface::Jacobian> iJac = MF;
@@ -220,16 +221,22 @@
NOX::Epetra::Group& grp = *(grpPtr.get());
Teuchos::RCP<NOX::StatusTest::NormF> absresid =
- Teuchos::rcp(new NOX::StatusTest::NormF(1.0e-12,
NOX::StatusTest::NormF::Unscaled));
+ Teuchos::rcp(new NOX::StatusTest::NormF(this->absolute_residual_tolerance,
NOX::StatusTest::NormF::Unscaled));
+ Teuchos::RefCountPtr<NOX::StatusTest::NormF> relresid =
+ Teuchos::rcp(new NOX::StatusTest::NormF(grp,
this->relative_residual_tolerance));
Teuchos::RCP<NOX::StatusTest::MaxIters> maxiters =
- Teuchos::rcp(new NOX::StatusTest::MaxIters(25));
+ Teuchos::rcp(new
NOX::StatusTest::MaxIters(this->max_nonlinear_iterations));
Teuchos::RCP<NOX::StatusTest::FiniteValue> finiteval =
Teuchos::rcp(new NOX::StatusTest::FiniteValue());
+ Teuchos::RCP<NOX::StatusTest::NormUpdate> normupdate =
+ Teuchos::rcp(new
NOX::StatusTest::NormUpdate(this->absolute_step_tolerance));
Teuchos::RCP<NOX::StatusTest::Combo> combo =
Teuchos::rcp(new NOX::StatusTest::Combo(NOX::StatusTest::Combo::OR));
combo->addStatusTest(absresid);
+ combo->addStatusTest(relresid);
combo->addStatusTest(maxiters);
combo->addStatusTest(finiteval);
+ combo->addStatusTest(normupdate);
Teuchos::RCP<NOX::Solver::Generic> solver =
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