[petsc-users] Inquiry about PetscDTSimplexQuadrature .

[Matthew Knepley]

On Fri, Jun 23, 2023 at 10:12 PM neil liu <liufield at gmail.com> wrote:

> Thanks, Matt.
> It seems DMPlexComputeCellGeometryFEM  works well with the quadrature
> points to deliver Jacobian and inverse one.
> Will it be a good choice ?
>

Yes, it is intended to compute these quantities for you. Let me know if it
does not do what you want.

  Thanks,

     Matt


> Have a good night.
>
> Thanks,
>
> On Fri, Jun 23, 2023 at 10:33 AM Matthew Knepley <knepley at gmail.com>
> wrote:
>
>> On Fri, Jun 23, 2023 at 10:28 AM neil liu <liufield at gmail.com> wrote:
>>
>>> Dear Petsc developers,
>>>
>>> I am learning  *PetscDTSimplexQuadrature *and plan to use it.
>>> I found that, in the biunit simplex (tetra),
>>> (-1,-1,-1),(1,-1,-1),(-1,1,-1),(-1,-1,1),
>>> degree 1: npoints 4, the sum of weights = 4/3(the volume of this simplex)
>>> degree 2 : npoints 8;
>>> For my previous experience, I used Gauss quadrature rules, (npoints =4 ,
>>> 5, 11, 15).
>>> Then  I am curious what rule is Petsc using ?
>>>
>>
>> There are two supported types:
>>
>>   - Stroud Conical Quadrature
>>
>>   - Minimal Symmetric Quadrature
>>
>> I think we prefer symmetric when it is available.
>>
>>
>>> And is *PetscDTSimplexQuadrature *used by PetscFE?
>>>
>>
>> Yes.
>>
>>   Thanks,
>>
>>     Matt
>>
>>
>>>
>>> Thanks a lot,
>>>
>>> Xiaodong
>>>
>>>
>>
>> --
>> 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
>>
>> https://www.cse.buffalo.edu/~knepley/
>> <http://www.cse.buffalo.edu/~knepley/>
>>
>

-- 
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

https://www.cse.buffalo.edu/~knepley/ <http://www.cse.buffalo.edu/~knepley/>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20230624/8898aab7/attachment.html>