[petsc-users] Inquiry regarding DMAdaptLabel function

[Pierre Jolivet]

> 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 <mailto: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).

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 <mailto:knepley at gmail.com>> wrote:
>>> On Sat, Feb 18, 2023 at 6:41 AM Zongze Yang <yangzongze at gmail.com <mailto: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 <mailto: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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