[petsc-users] non-manifold DMPLEX

Mon Dec 13 01:34:58 CST 2021

This would be a particularly useful example for testing the PETSc library,
as most applications are set on manifolds. There’s a recently-reformatted
chapter in the developers docs on how the testing works - this explains the
/* TEST */ blocks you see. If parts of these docs are confusing, that’s
very useful feedback for us!
https://petsc.org/release/developers/testing

Matthew Knepley <knepley at gmail.com> schrieb am Mo. 13. Dez. 2021 um 03:12:

> On Sun, Dec 12, 2021 at 4:36 PM TARDIEU Nicolas <nicolas.tardieu at edf.fr>
> wrote:
>
>> Dear Patrick and Matthew,
>>
>> Thank you very much for your answers. I am gonna try to set up such a
>> test by assigning cell types.
>> Shall I open a MR in order to contribute this example ?
>>
>
> Yes, that would be great.
>
>   Thanks,
>
>     Matt
>
>
>> Regards,
>> Nicolas
>>
>> ------------------------------
>> *De :* knepley at gmail.com <knepley at gmail.com>
>> *Envoyé :* dimanche 12 décembre 2021 12:17
>> *À :* Patrick Sanan <patrick.sanan at gmail.com>
>> *Cc :* TARDIEU Nicolas <nicolas.tardieu at edf.fr>; petsc-users at mcs.anl.gov
>> <petsc-users at mcs.anl.gov>
>> *Objet :* Re: [petsc-users] non-manifold DMPLEX
>>
>> On Sun, Dec 12, 2021 at 6:11 AM Patrick Sanan <patrick.sanan at gmail.com>
>> wrote:
>>
>> Here you have the following "points":
>>
>> - 1 3-cell (the cube volume)
>> - 7 2-cells (the 6 faces of the cube plus the extra one)
>> - 16 1-cells  (the 12 edges of the cube, plus 3 extra ones from the extra
>> face, plus the extra edge)
>> - 11 0-cells (the 8 vertices of the cube, pus 2 extra ones from the extra
>> face, plus the extra vertex)
>>
>> You could encode your mesh as here, by directly specifying relationships
>> between these points in the Hasse diagram:
>>
>> https://petsc.org/release/docs/manual/dmplex/#representing-unstructured-grids
>> <https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpetsc.org%2Frelease%2Fdocs%2Fmanual%2Fdmplex%2F%23representing-unstructured-grids&data=04%7C01%7Cnicolas.tardieu%40edf.fr%7Cb7faa53e924149df02bb08d9bd610c10%7Ce242425b70fc44dc9ddfc21e304e6c80%7C1%7C0%7C637749046784571371%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=NX0gPHyjCX3kU%2BZIAZwZQ4951FpJCdri36OzDfRoLbk%3D&reserved=0>
>>
>> Then, maybe the special relation is captured because you've defined the
>> "cone" or "support" for each "point", which tells you about the local
>> topology everywhere. E.g. to take the simpler case, three of the faces have
>> the yellow edge in their "cone", or equivalently the yellow edge has those
>> three faces in its "support".
>>
>>
>> This is correct. I can help you make this if you want. I think if you
>> assign cell types, you can even get Plex to automatically interpolate.
>>
>> Note that with this kind of mesh, algorithms which assume a uniform cell
>> dimension will break, but I am guessing you would not
>> be interested in those anyway.
>>
>>   Thanks,
>>
>>     Matt
>>
>>
>> Am Fr., 10. Dez. 2021 um 17:04 Uhr schrieb TARDIEU Nicolas via
>> petsc-users <petsc-users at mcs.anl.gov>:
>>
>> Dear PETSc Team,
>>
>> Following a previous discussion on the mailing list, I'd like to
>> experiment with DMPLEX with a very simple non-manifold mesh as shown in the
>> attached picture : a cube connected to a square by an edge and to an edge
>> by a point.
>> I have read some of the papers that Matthew et al. have written, but I
>> must admit that I do not see how to start...
>> I see how the define the different elements but I do not see how to
>> specify the special relationship between the cube and the square and
>> between the cube and the edge.
>> Once it will have been set correctly, what I am hoping is to be able to
>> use all the nice features of the DMPLEX object.
>>
>> Best regards,
>> Nicolas
>>
>>
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>> --
>> What most experimenters take for granted before they begin their
>> experiments is infinitely more interesting than any results to which their
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>> -- Norbert Wiener
>>
>> https://www.cse.buffalo.edu/~knepley/
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>> électronique arrivent en temps utile, sont sécurisées ou dénuées de toute
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>> ____________________________________________________
>>
>> This message and any attachments (the 'Message') are intended solely for
>> the addressees. The information contained in this Message is confidential.
>> Any use of information contained in this Message not in accord with its
>> purpose, any dissemination or disclosure, either whole or partial, is
>> prohibited except formal approval.
>>
>> If you are not the addressee, you may not copy, forward, disclose or use
>> any part of it. If you have received this message in error, please delete
>> it and all copies from your system and notify the sender immediately by
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>
>
> --
> 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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