[petsc-users] DMPlex and Tao

[Matthew Knepley]

On Wed, Jul 30, 2014 at 2:53 PM, Justin Chang <jychang48 at gmail.com> wrote:

> Hi,
>
> This might be a silly question, but I am developing a finite element code
> to solve the non-negative diffusion equation. I am using the DMPlex
> structure and plan on subjecting the problem to a bounded constraint
> optimization to ensure non-negative concentrations. Say for instance, I
> want to solve:
>
> min || K*u - F ||^2
> subject to u >= 0
>              M*u = 0
>
> Where K is the Jacobian, F the residual, u the concentration, and M some
> equality constraint matrix. I know how to do this via Tao, but my question
> is can Tao handle Mats and Vecs created via DMPlex? Because from the SNES
> and TS examples I have seen in ex12, ex62, and ex11, it seems there are
> solvers tailored to handle DMPlex created data structures.
>

Yes, TAO can handle objects created by DMPlex since they are just Vec and
Mat structures. The additions
to ex12, ex62, and ex11 concern the callbacks from the solver to the
constructions routines for residual and
Jacobian. Right now, none of the callbacks are automatic for TAO so you
would have to code them yourself,
probably by just calling the routines from SNES or TS so it should not be
that hard. We are working to get
everything integrated as it is in the other solvers.

  Thanks,

     Matt


> Thanks,
> Justin
>



-- 
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
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