[petsc-users] GMSH entities

[Matthew Knepley]

On Tue, May 14, 2024 at 9:07 AM Matthew Knepley <knepley at gmail.com> wrote:

> On Mon, May 13, 2024 at 10:04 PM Adrian Croucher <
> a.croucher at auckland.ac.nz> wrote:
>
>> On 14/05/24 1:44 pm, Matthew Knepley wrote:
>>
>> I wish GMsh was clearer about what is optional:
>> https://urldefense.us/v3/__https://gmsh.info/doc/texinfo/gmsh.html*MSH-file-format__;Iw!!G_uCfscf7eWS!fewn3DodeIVBmUE15mfIIEWSAHMhFjmoORD8nz_G4QnsaxhItWNFYbe4Lm0noV3Fuzj8ep504ww-M4Z0oroq$ 
>> They do talk about it, but not exhaustively. GMsh always writes and
>> $Entities block from what I can tell.
>> I can make it optional, it just might take until after the PETSc Meeting.
>>
>> Looks like $Entities are optional:
>>
>>
>> https://urldefense.us/v3/__https://gitlab.onelab.info/gmsh/gmsh/-/commit/b5feba2af57181ffa946d3f0c494b014603c6efa__;!!G_uCfscf7eWS!fewn3DodeIVBmUE15mfIIEWSAHMhFjmoORD8nz_G4QnsaxhItWNFYbe4Lm0noV3Fuzj8ep504ww-M57ksfou$ 
>>
>> I can also load a GMSH 4.1 file without $Entities into GMSH itself and it
>> doesn't complain, suggesting that they are indeed optional.
>>
>> Yes, but they are not careful to specify when a file can be inconsistent.
> For instance, omitting the $Entities, but then specifying entity numbers in
> the $Nodes block. I think they also thought this was inconsistent, but then
> got user complaints. The minimal example they show does exactly this.
>
>> If the $Entities aren't strictly needed for anything in DMPlex (which I'm
>> guessing they aren't, as the GMSH file format 2.2 doesn't even have them)
>> then it would be useful not to require them.
>>
> I put in some code for this:
> https://urldefense.us/v3/__https://gitlab.com/petsc/petsc/-/merge_requests/7546__;!!G_uCfscf7eWS!fewn3DodeIVBmUE15mfIIEWSAHMhFjmoORD8nz_G4QnsaxhItWNFYbe4Lm0noV3Fuzj8ep504ww-M-tMQE24$ 
>
> It just ignores entity numbers when there is no section.
>

This merged, so now it should be fixed for you.

  Thanks,

     Matt


>   Thanks,
>
>      Matt
>
>> - Adrian
>>
>> --
>> Dr Adrian Croucher
>> Senior Research Fellow
>> Department of Engineering Science
>> Waipapa Taumata Rau / University of Auckland, New Zealand
>> email: a.croucher at auckland.ac.nz
>> tel: +64 (0)9 923 4611
>>
>>
>
> --
> 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://urldefense.us/v3/__https://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!fewn3DodeIVBmUE15mfIIEWSAHMhFjmoORD8nz_G4QnsaxhItWNFYbe4Lm0noV3Fuzj8ep504ww-M7SPCKFm$ 
> <https://urldefense.us/v3/__http://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!fewn3DodeIVBmUE15mfIIEWSAHMhFjmoORD8nz_G4QnsaxhItWNFYbe4Lm0noV3Fuzj8ep504ww-MzikdTxP$ >
>


-- 
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://urldefense.us/v3/__https://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!fewn3DodeIVBmUE15mfIIEWSAHMhFjmoORD8nz_G4QnsaxhItWNFYbe4Lm0noV3Fuzj8ep504ww-M7SPCKFm$  <https://urldefense.us/v3/__http://www.cse.buffalo.edu/*knepley/__;fg!!G_uCfscf7eWS!fewn3DodeIVBmUE15mfIIEWSAHMhFjmoORD8nz_G4QnsaxhItWNFYbe4Lm0noV3Fuzj8ep504ww-MzikdTxP$ >
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