On Wed, Mar 9, 2011 at 10:47 AM, Roy Stogner <royst...@ices.utexas.edu> wrote:
>
> On Wed, 9 Mar 2011, John Peterson wrote:
>
>> I've just checked in a change which will hopefully please both the
>> people who need to call this->clear() at the end of
>> PetscNonlinearSolver::solve and the people who want
>> PetscNonlinearSolver::print_converged_reason() to work. The basic
>> idea is just to store the SNESConvergedReason at the end of the solve.
>> Then in print_converged_reason() it either re-gets the reason if
>> (_snes), otherwise (if SNES has since been destroyed) it uses the most
>> recently-stored value.
>
> This sounds like a decent workaround, but I'd like to understand the
> problem better. What causes the failure when the SNES object is kept
> around? Do some of the algorithm parameters get changed and then not
> reset?
I'd like to know in more detail what's actually happening as well but
haven't yet dug down into exactly what's going on. If we don't clear
after each solve, then during the following call to init() we don't
execute the code block in this section
if(this->_preconditioner)
{
...
}
That would probably be where I'll start looking...
>> I'm not sure yet what to do about the old_dof_object stuff. Roy, I
>> think we could definitely use your insight there. We have some tests
>> here which aren't actually crashing, but do have solution diffs to our
>> "gold" files.
>
> That's a surprising problem. I'm not sure what the solution is except
> to throw an assertion in before those new lines and see what's
> triggering the continue. I'd have expected anything that hits the
> continue there to already have been dying in debug mode when it
> requests old dofs that don't exist.
>
> Wait... is the problem that we're not testing the right thing(s) for
> old dofs? That elem->old_dof_object->has_dofs(system.number()) ought
> to be returning false in instances where the FE space being used
> doesn't store any Dofs on the Elem because they're all on nodes,
> right? And in that case we definitely do *not* want to continue.
>
> Okay, instead of this:
>
> ---
>
> if (!elem->old_dof_object ||
> !elem->old_dof_object->has_dofs(system.number()))
> continue;
>
> ---
>
> Try this:
>
> ---
>
> bool missing_old_dofs = !elem->old_dof_object ||
> (elem->has_dofs(system.number()) &&
> !elem->old_dof_object->has_dofs(system.number())); for (n = 0;
> !missing_old_dofs && n != elem->n_nodes(); ++n)
> {
> Node *node = elem->get_node(n);
> missing_old_dofs = !node->old_dof_object ||
> (node->has_dofs(system.number()) &&
> !node->old_dof_object->has_dofs(system.number()));
> {
>
> if (missing_old_dofs)
> continue;
I will try this in our tests and let you know what happens.
--
John
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