[petsc-users] Finite difference approximation of Jacobian

[Matthew Knepley]

On Sat, Dec 11, 2021 at 1:58 PM Tang, Qi <tangqi at msu.edu> wrote:

> Hi,
> Does anyone have comment on finite difference coloring with DMStag? We are
> using DMStag and TS to evolve some nonlinear equations implicitly. It would
> be helpful to have the coloring Jacobian option with that.
>

Since DMStag produces the Jacobian connectivity, you can
use -snes_fd_color_use_mat. It has many options. Here is an example of us
using that:

  https://gitlab.com/petsc/petsc/-/blob/main/src/snes/tutorials/ex19.c#L898

  Thanks,

     Matt


> Thanks,
> Qi
>
>
> On Oct 15, 2021, at 3:07 PM, Jorti, Zakariae via petsc-users <
> petsc-users at mcs.anl.gov> wrote:
>
> Hello,
>
> Does the Jacobian approximation using coloring and finite differencing of
> the function evaluation work in DMStag?
> Thank you.
> Best regards,
>
> Zakariae
>
>
>

-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
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