[petsc-users] Augmented Lagrangian examples?

[Justin Chang]

Matt,

So inside these TAO routines, if I wanted to include the boundary values,
would I follow the approaches in functions like
DMPlexComputeResidual/Jacobian_Internal? I assume I need something like:

DMGetLocalVector(dm,xlocal);
DMPlexInsertBoundaryValues(xlocal,...);
** use xlocal to compute equality constraints/jacobian **
DMRestoreLocalVector(dm,xlocal);

The Jacobian and equality constraints that I want to assemble are not the
same as the DM matrix use for the entire problem. I am guessing I will need
to use a different DS for the DM because, for example the stokes problem
with TH elements, I want to assemble an equality jacobian of size (no. of
cells) by (no. of velocity dofs), and an equality constraints vector of
size (no. of cells). How would I go about doing a problem like this?

Thanks,
Justin


On Mon, Aug 10, 2015 at 10:01 AM, Matthew Knepley <knepley at gmail.com> wrote:

> On Mon, Aug 10, 2015 at 9:56 AM, Justin Chang <jychang48 at gmail.com> wrote:
>
>> Hi all,
>>
>> 1) I ran across this paper:
>>
>> http://web.stanford.edu/~egawlik/pdf/GaMuSaWi2012.pdf
>>
>> and was wondering if there are any current TAO examples that do this.
>>
>> also
>>
>> 2) If I integrate this into an FEM (from DMPlex) I will need to assemble
>> an equality jacobian matrix and constraint vector. But the element-wise
>> constraints that I need to compute (e.g., the divergence) needs all degrees
>> of freedom within the element closure including the essential BCs DMPlex
>> removes from the global matrix/vector. So how can I work around this and/or
>> access said removed terms inside a TAO routine?
>>
>
> Those are not really dofs, they are boundary values, so they are not in
> the global system. The local vectors have
> the boundary values, so you can calculate the correct constraint eqns to
> put in the global system.
>
>    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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