[petsc-users] Setting a custom predictor in the generalized-alpha time stepper

[Jed Brown]

I think you can use TSGetSNES() and SNESSetComputeInitialGuess() to modify the initial guess for SNES. Would that serve your needs? Is there anything else you can say about how you'd like to compute this initial guess? Is there a paper or something?

David Kamensky <david at coreform.com> writes:

> Hi,
>
> My understanding is that the second-order generalized-alpha time stepper in
> PETSc uses a same-displacement predictor as the initial guess for the
> nonlinear solver that executes in each time step.  I'd like to be able to
> set this to something else, to improve convergence.  However, my
> (possibly-naive) attempts to use `TSSetPreStep` and `TSSetPreStage` haven't
> worked out.  Is there any way to set a custom predictor?
>
> Thanks,
> David Kamensky