[petsc-users] Divergence when using Line Search

[Dmitry Karpeev]

In principle, you can implement any type of line search in PETSc by
subclassing SNESLineSearch (although it requires going under the hood some,
as we generally think of LineSearch as a private object).  If you can
elaborate on what you need, we can work with you guys to see how to
accomplish it with what we have or to extend it, if necessary.  That might
require extra hooks into PETSc in libMesh/Moose, but we have plenty of
experience managing that.

Cheers,
Dmitry.

On Tue, May 15, 2012 at 4:45 PM, Jed Brown <jedbrown at mcs.anl.gov> wrote:

> On Tue, May 15, 2012 at 3:32 PM, Avery Bingham <avery.bingham at gmail.com>wrote:
>
>> I have also seen this behavior, and I think this might be related to the scaling of the variables in the nonlinear system.  I am using PETSc through an application of MOOSE which allows for scaling of the variables.  This scaling reduces the chance that the default cubic backtracking line search fails, but it is not reliable on all problems. Would it be possible to get a scaling-independent Line Search Method implemented within PETSc?
>>
>>
> I'm not sure what you mean by scaling, but there is -snes_linesearch_type
> cp (critical point) that might be useful.
>
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