[petsc-users] Discretized fields at quadrature points

[Matthew Knepley]

On Fri, Apr 8, 2016 at 12:07 PM, Sander Arens <Sander.Arens at ugent.be> wrote:

> Or perhaps there should be a flag for PETSCDUALSPACELAGRANGE to evaluate
> at the quadrature points?
>

I think you can get what you want using DUALSPACESIMPLE and pass the
quadrature.

   Matt


> On 8 April 2016 at 17:35, Sander Arens <Sander.Arens at ugent.be> wrote:
>
>> What does it stand for? Discrete Gauss? Maybe PETSCSPACEQUADRATURE is a
>> better name?
>>
>> The reason I want to use this is because these fields will be
>> representing a bunch of ODE's at each point (not coupled spatially) and it
>> would be nice if their mass matrices would be diagonal. So the dual space
>> should be Dirac delta's at the quadrature points and that's different from
>> the default (Lagrange).
>>
>> I'll see if I can code something up for this. Any suggestions for a name
>> for this dual space?
>>
>> Thanks,
>> Sander
>>
>> On 8 April 2016 at 16:48, Matthew Knepley <knepley at gmail.com> wrote:
>>
>>> On Wed, Apr 6, 2016 at 2:06 PM, Sander Arens <Sander.Arens at ugent.be>
>>> wrote:
>>>
>>>> Hi,
>>>>
>>>> I'd like to be able to represent some discretized fields at the
>>>> quadrature points of a finite element, so I can easily use them with the
>>>> plex residual/function evaluations. Is it possible to do this with
>>>> PetscFECreateDefault and some command line options?
>>>> I think what I need is PETSCSPACEDG for the space, but I'm not sure
>>>> what type I should take for the dual space?
>>>>
>>>
>>> This is why I put that in there. It really should not be named DG, but
>>> there are reasons I thought it made sense.
>>>
>>> I had not thought about a dual space, since I was not going to project
>>> into it. I think you can just use whatever is the default.
>>>
>>>   Matt
>>>
>>>
>>>> Thanks,
>>>> Sander
>>>>
>>> --
>>> 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
>>>
>>
>>
>


-- 
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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