dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Anders Logg wrote:
> On Wed, Nov 05, 2008 at 08:17:25AM +0000, Garth N. Wells wrote:
> > Anders Logg wrote:
> > > On Tue, Nov 04, 2008 at 10:49:48PM +0000, Garth N. Wells wrote:
> > > > Any problem in adding a field to the Mesh xml format that states if the 
> > > > connectivity has been ordered?
> > > >
> > > > Garth
> > > Isn't it better to just read in the mesh and then call mesh.ordered()?
> > > That will give the right answer, whereas a flag may have been set
> > > incorrectly.
> > Well, we'll need to have a very close look at how we read in 
> > MeshFunctions because the because the position of the mesh.order() call 
> > can mess things up without producing an error or warning message.
> >
> > Garth
>
> Is the problem that mesh.order() will possibly mess up data stored in
> MeshFunctions? I don't understand why that should happen. The
> reordering is only performed locally. The global entity indices remain
> the same.

Take a look at the Stokes Taylor-Hood demo. Doing

  Mesh mesh("../../../../../data/meshes/dolfin-2.xml.gz");
  MeshFunction<unsigned int> sub_domains(mesh, "../subdomains.xml.gz");
  mesh.order();

works as expected, but

  // Read mesh and sub domain markers
  Mesh mesh("../../../../../data/meshes/dolfin-2.xml.gz");
  mesh.order();
  MeshFunction<unsigned int> sub_domains(mesh, "../subdomains.xml.gz");

screws up the boundary conditions.

Garth

> Or is the problem only with Functions?
>
>
>
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