[petsc-users] A question about DMPlexDistribute

[Matthew Knepley]

On Thu, Aug 11, 2016 at 8:00 PM, leejearl <leejearl at 126.com> wrote:

> Thank you for your reply. I have attached the code, grid and the error
> message.
>
> cavity.c is the code file, cavity.exo is the grid, and error.dat is the
> error message.
>
> The command is "mpirun -n 2 ./cavity
>

Can you verify that you are running the master branch? I just ran this and
got

DM Object: 2 MPI processes
  type: plex
DM_0x84000004_0 in 2 dimensions:
  0-cells: 5253 5252
  1-cells: 10352 10350
  2-cells: 5298 (198) 5297 (198)
Labels:
  ghost: 2 strata of sizes (199, 400)
  vtk: 1 strata of sizes (4901)
  Cell Sets: 1 strata of sizes (5100)
  Face Sets: 3 strata of sizes (53, 99, 50)
  depth: 3 strata of sizes (5253, 10352, 5298)

  Thanks,

     Matt


> On 2016年08月11日 23:29, Matthew Knepley wrote:
>
> On Thu, Aug 11, 2016 at 3:14 AM, leejearl <leejearl at 126.com> wrote:
>
>> Hi,
>>     Thank you for your reply. It help me very much.
>>     But, for "/petsc-3.7.2/src/ts/examples/tutorials/ex11.c", when I set
>> the overlap to 2 levels, the command is
>> "mpirun -n 3 ./ex11 -f annulus-20.exo -ufv_mesh_overlap 2 -physics sw",
>> it suffers a error.
>>     It seems to me that setting overlap to 2 is very common. Are there
>> issues that I have not take into consideration?
>>     Any help are appreciated.
>>
> I will check this out. I have not tested an overlap of 2 here since I
> generally use nearest neighbor FV methods for
> unstructured stuff. I have test examples that run fine for overlap > 1.
> Can you send the entire error message?
>
> If the error is not in the distribution, but rather in the analytics, that
> is understandable because this example is only
> intended to be run using a nearest neighbor FV method, and thus might be
> confused if we give it two layers of ghost
> cells.
>
>    Matt
>
>
>>
>> leejearl
>>
>> On 2016年08月11日 14:57, Julian Andrej wrote:
>>
>> Hi,
>>
>> take a look at slide 10 of [1], there is visually explained what the
>> overlap between partitions is.
>>
>> [1] https://www.archer.ac.uk/training/virtual/files/2015/06-
>> PETSc/slides.pdf
>>
>> On Thu, Aug 11, 2016 at 8:48 AM, leejearl <leejearl at 126.com> wrote:
>>
>>> Hi, all:
>>>     I want to use PETSc to build my FVM code. Now, I have a question
>>> about
>>> the function  DMPlexDistribute(DM dm, PetscInt overlap, PetscSF *sf, DM
>>> *dmOverlap) .
>>>
>>>     In the example "/petsc-3.7.2/src/ts/examples/tutorials/ex11.c".
>>> When I set the overlap
>>> as 0 or 1, it works well. But, if I set the overlap as 2, it suffers a
>>> problem.
>>>     I am confused about the value of overlap. Can it be set as 2? What
>>> is the meaning of
>>> the parameter overlap?
>>>     Any helps are appreciated!
>>>
>>> leejearl
>>>
>>>
>>>
>>>
>>
>>
>
>
> --
> 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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