[petsc-users] Using -ts_type sundials with -snes-fd

[Geoff Oxberry]

Peter,

Just wanted to make sure there wasn't some Sundials-specific option for finite difference Jacobians that I was missing; despite reading the manual, it's a large package, and it's easy to miss things. If that's the case, I'd like to make a feature request for such an option.

Geoff

On Jun 21, 2012, at 9:53 AM, Peter Brune wrote:

> Note that in the code in ts/impls/implicit/sundials it says:
> 
> This uses its own nonlinear solver and krylov method so PETSc SNES and KSP options do not apply...
> 
> - Peter
> 
> On Jun 21, 2012 7:59 AM, "Geoff Oxberry" <goxberry at gmail.com> wrote:
> Running the following example from PETSC 3.3.0-dev (changeset: 23631:0e86ac5e4170)
> 
> /path/to/petsc-dev/src/ts/examples/tutorials/ex8 -problem_type rober -snes_fd -ts_type sundials
> 
> gives the following output
> 
> steps 1000 (0 rejected, 0 SNES fails), ftime 744.845, nonlinits 3739, linits 3739
> WARNING! There are options you set that were not used!
> WARNING! could be spelling mistake, etc!
> Option left: name:-snes_fd no value
> 
> Just to confirm, is it currently impossible to use a finite difference Jacobian matrix in concert with CVODE? If so, could this feature be implemented in a future release? I currently rely on Sundials to integrate stiff systems of ODEs, and for my application, it is impractical to derive an analytical Jacobian matrix. (It is an issue I've discussed both with Jed and Matt on another forum.)
> 
> Cheers,
> 
> Geoff

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