[Gmsh] Entity numbering
Christophe Geuzaine
cgeuzaine at ulg.ac.be
Sun Jan 18 13:04:40 CET 2009
David Andrs wrote:
> Hi!
>
> We are using gmsh for post-processing purposes in our hp-FEM code hermes3d.
>
> We number all mesh entities (elements, vertices, edges, faces) from zero
> and we have the following problem with gmsh:
>
> - We list the vertices in the $Nodes section, starting from 0, but the
> vertex with the zeroth index is shown as 1.
>
> - The same behavior with elements and $Elements section. If we use more
> $Elements sections, than the zeroth entity is display with two, three,
> etc. So it seems that the 0 has some special meaning (some sort of auto
> increment?)
>
> The file with the mesh for testing can be found on
> http://spilka.math.unr.edu/~andrsd/ref.msh
>
> Is there a possibility to turn off this auto-increment option and have
> the entities numbered from 0? If not, could you consider implementing
> such a feature?
Unfortunately, no: we use "0" as a special index. Cf. the documentation:
@var{node-number} is the number (index) of the @var{n}-th node in the
mesh; @var{node-number} must be a postive (non-zero) integer. Note that
the @var{node-number}s do not necessarily have to form a dense nor an
ordered sequence.
>
> The gmsh we are using is 2.2.5.
>
> Thanks,
> --
> David Andrs
>
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>
--
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine