[petsc-dev] resurrecting the finite element energy functions thread

[Lisandro Dalcin]

On 19 January 2014 18:26, Jed Brown <jed at jedbrown.org> wrote:
> Geoffrey Irving <irving at naml.us> writes:
>
>> After a brief delay, I'm back to needing finite element energy
>> functions for optimization problems.  The original thread is
>>
>>     http://lists.mcs.anl.gov/pipermail/petsc-dev/2013-December/014161.html
>>
>> That thread veered off into some more general discussions of the
>> PetscFE API, and I don't think came to a specific conclusion as to the
>> best way to add said energy functions.  In terms of API, what is
>> missing is a function to integrate a function over a space, where the
>> functions takes various field arguments and produces one or more
>> scalars.  The quadrature rule is important: in my case there will be
>> only one non-auxiliary field, and the integration function needs to
>> use the same quadrature rule.
>
> I would define a number of quantities and a reducer (MPI_SUM, MPI_MAX).
>

I thought to do that in PetIGA, but then realized that a reducer+eval
at quadrature points+MPI_MAX sounds weird (though I can imagine some
use cases). A reduce with MPI_MAX is a lucky consequence of computing
integrals through quadrature.

>> I apologize if I failed to read through the previous discussion
>> correctly, and/or the required function has already been written.  If
>> not, I'm happy to mock something up, ideally with function signature
>> suggestions from others first.
>
> What is different from integrating a residual, apart from the result
> being a set of scalars instead of a vector?

It is pretty much the same.


-- 
Lisandro Dalcin
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