[petsc-users] Inquiry regarding DMAdaptLabel function

[Matthew Knepley]

On Mon, Feb 27, 2023 at 10:13 AM Pierre Jolivet <pierre at joliv.et> wrote:

> On 27 Feb 2023, at 3:59 PM, Matthew Knepley <knepley at gmail.com> wrote:
>
> 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
>
>
> :)
> Matt probably meant “the _DMPlex interface_ to adaptive refinement
> software has not seen wide use”, Mmg has been rather widely used for 10+
> years (here is a 13-year old presentation
> https://www.ljll.math.upmc.fr/hecht/ftp/ff++days/2010/exposes/Morice-MeshMetric.pdf
> ).
>

The interface is certainly new, but even ParMMG is only from Nov 2016,
which is very new if you are an old person :)

  Thanks,

    Matt


> Thanks,
> Pierre
>
> , 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/>
>
>
>

-- 
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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