[petsc-users] Inquiry about PetscDTSimplexQuadrature .

[neil liu]

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

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/>
>
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