syfi team mailing list archive

[Kent-Andre Mardal <kent-and@xxxxxxxxx>]

tir, 23,.01.2007 kl. 12.10 +0100, skrev Robert Cimrman:
> Anders Logg wrote:
> > So there are two steps: First number all entities based on a
> > lexicographical ordering as in the UFC manual, then number everything
> > else based on the global index.
> > 
> > UFC is only concerned with the first step.
> > 
> > We also need to define something we can call "alignment", which is how
> > two cells meet at a common facet. For two triangles, the alignment is
> > 0 or 1. For two tetrahedra, the alignment is 0, 1, 2, 3, 4 or 5.
> > This can also be based on a lexicographical ordering of matching
> > vertices.
> 
> Hi,
> 
> I have installed SyFi with the aim to integrate it with my
> NumPy/SciPy-based Python FE code (just released at
> http://ui505p06-mbs.ntc.zcu.cz/sfe), so I am silently watching this
> list. Now I have hijacked your discussion because I have implemented
> this alignment (called orientation) in C, based on lexicographical
> naming, too, albeit for edges only (0 or 1).
> In 3D I have not needed more than P2 elements (edge nodes only), so I
> avoided the thing, as it was getting complicated (tetra- and hexa-edra
> together, wedge elements, pyramides...). Are you going to consider also
> those mixed element type meshes? 

I have not thought about it. What is the advantage with these polygons? 



> Do you allow degenerated elements? 

What are degenerated elements  ? Do they have very large aspect ratio or
are they degenerated in some other way ? 

> I
> would like to have this finally in my code. (I silently assume you need
> the alignment to be able to assign global numbers to the extra element
> nodes, that are not present in the underlying mesh. If this was not the
> case, ignore the message, please.)
> best regards,
> Robert Cimrman


We have our own dof-handler, so we can handle dofs that are not present
in the mesh. In fact, we have a very general dof-handler so I think we
can handle just about any dof ( The dof-handler is templated in
terms of the dof and a comparison function for the dof.)


Kent