Thanks Norbert! This is something that's been on my list for a while
now.
I'm finishing up an abstract for a conference today... then I'll take
a look at this and get it committed... and then I should be freed up
to do some work on this stuff myself.
Thanks again,
Derek
On Oct 29, 2008, at 9:05 AM, Norbert Stoop wrote:
> 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 =
> -------------------------------------------------------------------------
> This SF.Net email is sponsored by the Moblin Your Move Developer's
> challenge
> Build the coolest Linux based applications with Moblin SDK & win
> great prizes
> Grand prize is a trip for two to an Open Source event anywhere in
> the world
> http://moblin-contest.org/redirect.php?banner_id=100&url=/_______________________________________________
> Libmesh-devel mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/libmesh-devel
-------------------------------------------------------------------------
This SF.Net email is sponsored by the Moblin Your Move Developer's challenge
Build the coolest Linux based applications with Moblin SDK & win great prizes
Grand prize is a trip for two to an Open Source event anywhere in the world
http://moblin-contest.org/redirect.php?banner_id=100&url=/
_______________________________________________
Libmesh-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/libmesh-devel
