[Trilinos-Users] [EXTERNAL] Running Rythmos DAE with a user defined Epetra_Operator as Jacobian
amola at sissa.it
Thu May 22 12:35:47 MDT 2014
I am continuing to struggle in implementing a Rythmos DAE. As previously
suggested in this thread, I have converted the EpetraExt::ModelEvaluator
to a Thyra::ModelEvaluator, and managed to run Rythmos with a
user-defined Epetra_Operator as Jacobian.
Unfortunately, I still haven't had success in using a used-defined
Epetra_Operator as Jacobian preconditioner.
Within my Thyra::ModelEvaluator, I define a Thyra::linearOpWithSolve and
initialize it with the initializePreconditionedOp method so as to
specify my own preconditioner. If I try a "test run" for the resulting
linear system with solve, it works correctly and the preconditioner
matrix-vector (the Apply member of the preconditioner Epetra_Operator)
is correctly called multiple times during the system resolution.
But for some reason, during the time integration Rythmos is completely
ignoring the preconditioner, and the corresponding matrix-vector product
is never called. The OutArgs of my Thyra::ModelEvaluator support W,
W_op, and W_prec. I thought that maybe I should re-initialize
linearOpWithSolve at each evaluation. But this is not even possible,
since the W and W_prec pointers assigned during the time integration to
the evalModel function are always null.
I initially thought that Eric's concerns regarding the user defined
preconditioner in Rythmos were only referred to
EpetraExt::ModelEvaluator, but I am now afraid that they were also
referred to the Thyra class. So is there a way to provide a user-defined
preconditioner to Rythmos? Has anyone succeeded in doing that?
Thanks a lot for the help.
On 2014-05-05 18:34, Andrea Mola wrote:
> I am currently using version 11.2.3, but maybe the issue isn't there.
> I realized the problem was most likely my fault. The create_W method
> in the model evaluator class was returning an Epetra_CrsMatrix. I
> never called that method, so I din't know it was effectively used.
> Nonetheless, I now run into a further exception
> terminate called after throwing an instance of 'std::logic_error'
> Throw number = 1
> Throw test that evaluated to true: !allFuncsWhereScaled
> Error, we can not currently handle epetra output objects that could
> not be scaled. Special code will have to be added to handle this
> (i.e. using implicit diagonal and multiplied linear operators to
> implicitly do the scaling.
> which is maybe called because in my operator some methods are not
> properly set.
> However, given the possible preconditioning problems you are hinting
> at, I'm converting everything into a Thyra model evaluator, as
> previously suggested by Roscoe.
> Thanks for the help.
> On 2014-05-05 16:36, Phipps, Eric T wrote:
>> What version of Trilinos are you using? I believe Andy Salinger
>> fixed some of these issues when using an Epetra_Operator generated
>> from an
>> EpetraExt::ModelEvaluator in Rythmos. However I believe those fixes
>> only in the development branch which should be accessible from the
>> git repository. Even with the fix for the failed dynamic casts,
>> there may still be an issue with supplying a user-defined
>> to Rythmos.
>> On 5/5/14, 7:45 AM, "Andrea Mola" <amola at sissa.it> wrote:
>>> Dear all,
>>> I am trying to use Ryrhmos to solve a DAE system for the time
>>> advancement of a PDE system.
>>> So far, I have already been able to set up a small example which
>>> correctly a small DAE using a Jacobian defined as an
>>> Unfortunately, I need to use a different Linear Operator, which I
>>> as an Epetra_Operator (JacobianOperator :public Epetra_Operator). The
>>> problem comes when I define my AztecOOLinearOpWithSolveFactory to be
>>> passed to my EpetraExt::ModelEvaluator constructor. Even though I try
>>> specify through the Thyra::initializeOp function that I will use a
>>> JacobianOperator instead of an Epetra_CrsMatrix, it still seems to
>>> that the jacobian of my system is an Epetra_CrsMatrix. In fact, upon
>>> execution, when the model evaluator calls for a Jacobian evaluation,
>>> dynamic cast
>>> JacobianOperator &jac = dyn_cast<JacobianOperator>(*W_out);
>>> fails with the following exception
>>> terminate called after throwing an instance of 'Teuchos::m_bad_cast'
>>> Throw number = 1
>>> Throw test that evaluated to true: true
>>> dyn_cast<16JacobianOperator>(15Epetra_Operator) : Error, the object
>>> the concrete type '16Epetra_CrsMatrix' (passed in through the
>>> type '15Epetra_Operator') does not support the interface
>>> '16JacobianOperator' and the dynamic cast failed!
>>> So, my question is: what should I do to be able to use an arbitrary
>>> Epetra_Operator in an EpetraExt::ModelEvaluator? I am not very
>>> with the parameter lists, so probably the answer is there. Or,
>>> Thyra::initializeOp is just the wrong function to do what I need. Can
>>> anyone point me out an example that does that, or suggest me some
>>> Thank you very much in advance for the help.
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>>> Trilinos-Users at software.sandia.gov
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