[petsc-users] Inquiry regarding DMAdaptLabel function

[Matthew Knepley]

On Mon, Feb 27, 2023 at 9:53 AM Zongze Yang <yangzongze at gmail.com> wrote:

> Hi, Matt,
>
> I tested coarsening a mesh by using ParMMg without firedrake, and found
> some issues:
>  see the code and results here:
> https://gitlab.com/petsc/petsc/-/issues/1331
>
> Could you have a look and give some comments or suggestions?
>

I replied on the issue. More generally, the adaptive refinement software
has not seen wide use, and I expect
more of these kinds of bugs until more people use it.

  Thanks,

     Matt


> Best wishes,
> Zongze
>
>
> On Mon, 27 Feb 2023 at 20:19, Matthew Knepley <knepley at gmail.com> wrote:
>
>> On Sat, Feb 18, 2023 at 6:41 AM Zongze Yang <yangzongze at gmail.com> wrote:
>>
>>> Another question on mesh coarsening is about `DMCoarsen` which will fail
>>> when running in parallel.
>>>
>>> I generate a mesh in Firedrake, and then create function space and
>>> functions, after that, I get the dmplex and coarsen it.
>>> When running in serials, I get the mesh coarsened correctly. But it
>>> failed with errors in ParMMG when running parallel.
>>>
>>> However, If I did not create function space and functions on the
>>> original mesh, everything works fine too.
>>>
>>> The code and the error logs are attached.
>>>
>>
>> I believe the problem is that Firedrake and PETSc currently have
>> incompatible coordinate spaces. We are working
>> to fix this, and I expect it to work by this summer.
>>
>>   Thanks,
>>
>>      Matt
>>
>>
>>> Thank you for your time and attention。
>>>
>>> Best wishes,
>>> Zongze
>>>
>>>
>>> On Sat, 18 Feb 2023 at 15:24, Zongze Yang <yangzongze at gmail.com> wrote:
>>>
>>>> Dear PETSc Group,
>>>>
>>>> I am writing to inquire about the function DMAdaptLabel in PETSc.
>>>> I am trying to use it coarse a mesh, but the resulting mesh is refined.
>>>>
>>>> In the following code, all of the `adpat` label values were set to 2
>>>> (DM_ADAPT_COARSEN).
>>>> There must be something wrong. Could you give some suggestions?
>>>>
>>>> ```python
>>>> from firedrake import *
>>>> from firedrake.petsc import PETSc
>>>>
>>>> def mark_all_cells(mesh):
>>>>     plex = mesh.topology_dm
>>>>     with PETSc.Log.Event("ADD_ADAPT_LABEL"):
>>>>         plex.createLabel('adapt')
>>>>         cs, ce = plex.getHeightStratum(0)
>>>>         for i in range(cs, ce):
>>>>             plex.setLabelValue('adapt', i, 2)
>>>>
>>>>     return plex
>>>>
>>>> mesh = RectangleMesh(10, 10, 1, 1)
>>>>
>>>> x = SpatialCoordinate(mesh)
>>>> V = FunctionSpace(mesh, 'CG', 1)
>>>> f = Function(V).interpolate(10 + 10*sin(x[0]))
>>>> triplot(mesh)
>>>>
>>>> plex = mark_all_cells(mesh)
>>>> new_plex = plex.adaptLabel('adapt')
>>>> mesh = Mesh(new_plex)
>>>> triplot(mesh)
>>>> ```
>>>>
>>>> Thank you very much for your time.
>>>>
>>>> Best wishes,
>>>> Zongze
>>>>
>>>
>>
>> --
>> 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/>
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