[petsc-users] PetscFEM fe vs. feAux vs. feBd

[Matthew Knepley]

On Thu, Nov 14, 2013 at 2:42 PM, Geoffrey Irving <irving at naml.us> wrote:

> What is the difference between the fe and feAux fields in PetscFEM?
> Do they (and feBd) have to refer to distinct PetscFE objects, or can I
> reuse one set of finite element spaces?
>

fe contains the fields that we are solving for, feAux contains the fields
we will
use the in the problem but not solve for, like coefficients. They can
obviously
come from different spaces.


> In particular, based on snes ex12, it doesn't look like feBd contains
> the logic for what the boundary is.  This information appears to be
> extracted by DMPlexComputeResidualFEM and friends.  If so, does that
> mean PetscFEM doesn't have support for several different boundary
> routines evaluated over different parts of the boundary?  I don't
> necessarily need this support at the moment, but I want to check
> whether I'm reading the code correctly.
>

Yep, right now there is a single boundary marker and set of pointwise
functions.
I was not going to make a set of them until I needed it, but we do use that
in
TS ex11. This would work the same way.

   Matt


> Thanks,
> Geoffrey
>



-- 
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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