j s wrote:
Hello,
It would been far better to require unique physical id's across
dimensions and change the documentation. The nature of the old mesh
format made an implicit requirement that the physical numbers be
unique.
Non, that's incorrect.
If I had found that small piece of information concerning
non-uniqueness of id's a year ago, I would have pointed out the
ambiguity then.
The ambiguity only existed for physical *names*, not numerical ids.
The added complexity is encoding the dimensionality of each element when
parsing the file format. Perhaps you should consider placing the
highest order dimensionality as a parameter in the mesh format as well?
Again, nothing prevents you to define *your* physical ids to be unique
across all dimensions.
Juan
On Wed, Sep 2, 2009 at 2:46 PM, Christophe Geuzaine <[email protected]
<mailto:[email protected]>> wrote:
j s wrote:
My gmsh reader relies on the fact that each physical number is
unique across dimensions. Are you saying this is no longer
happening?
Hi Juan - Physical entity ids have *never* been unique across
dimensions---cf. the documentation. As with elementary entity ids,
they must be unique per dimension. (You cannot have Nurbs(1) and
Spline(1), but you can have Point(1) and Spline(1). This is deeply
rooted in the boundary representation model used by Gmsh.)
Of course, nothing prevents you from *choosing* unique physial ids
gobally... This was basically what we forced when assigning names
instead of numerical ids to physicals in the previous version of the
mesh file. This was an oversight, since it could lead to ambigious
cases when reading a mesh.
This is going to be a few hours effort to change my algorithm,
so please help me understand all of the ramifications correctly.
I then need to check the dimensionality of each element I am
reading in and assign it to a different group according to
number and dimension? Why can't we just use names instead of
numbers, and ensure that the names are unique across all
dimensionalities?
Juan
On Wed, Sep 2, 2009 at 7:59 AM, Christophe Geuzaine
<[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>> wrote:
Geordie McBain wrote:
On Mon, Aug 31, 2009 at 11:07 AM, Rui
Maciel<[email protected] <mailto:[email protected]>
<mailto:[email protected] <mailto:[email protected]>>> wrote:
Does anyone know what changed between the previous
and the
new file format
version?
The motivation,according to doc/VERSIONS.txt is `bumped
mesh version
format to 2.1
(small change in the $PhysicalNames section, where the group
dimension
is now required)'.
Exactly: it's a very small change, only affecting the optional
$PhysicalNames/$EndPhysicalNames section.
The problem was that with version 2, we did not save a dimension
(0D, 1D, 2D or 3D) together with the name. Hence we could not
guarantee a one-to-one mapping between physical names and
physical
numbers. Indeed, physical numbers need only to be unique per
dimension (you can have Physical Point(1) and Physical Line(1)).
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-- Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
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--
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine
<http://www.montefiore.ulg.ac.be/%7Egeuzaine>
--
Prof. Christophe Geuzaine
University of Liege, Electrical Engineering and Computer Science
http://www.montefiore.ulg.ac.be/~geuzaine
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