Dolfin mesh smoothing broken

[Olaf Schumann]

Mesh smoothin in fenics 1.1.0 does not work on my Computer. I have Ubuntu 12.04 with the Fenics Packages from http://fenicsproject.org/download/ubuntu_details.html#ubuntu-details

If I create a very simple 2D Mesh with

> mesh=UnitSquareMesh(2,2)

and an immediate smoothing

> mesh.smooth(1)

The resulting Mesh is broken

> mesh.coordinates()
array([[ 0. , 0. ],
             [ 0.5 , 0. ],
             [ 1. , 0. ],
             [ 0. , 5. ],
             [ nan, nan],
             [ 1. , 0.5 ],
             [ 0. , 1. ],
             [ 0.5 , 1. ],
             [ 1. , 1. ]])

[Johannes Ring (johannr)]

Confirmed for 1.1.x and trunk.

It works fine with 1.0.x.

[Anders Logg (logg)]

This is broken because someone broke the connectivity computation for 0-0 connectivity. I found the following in TopologyComputation.cpp. It just sets every vertex to be connected to itself. Why was this changed?

 if (d0 == 0 && d1 == 0)
  {
    std::vector<std::vector<std::size_t> >
      connectivity00(topology.size(0), std::vector<std::size_t>(1));
    for (MeshEntityIterator v(mesh, 0); !v.end(); ++v)
      connectivity00[v->index()][0] = v->index();
    topology(0, 0).set(connectivity00);
  }

[Garth Wells (garth-wells)]

On Tuesday, 19 March 2013, Anders Logg wrote:

> This is broken because someone broke the connectivity computation for
> 0-0 connectivity. I found the following in TopologyComputation.cpp. It
> just sets every vertex to be connected to itself. Why was this changed?
>
>
This was discussed on the mailing list.

It was changed because it makes a bunch of algorithms work in any
dimension. Specifically, it was changed to make the parallel code work in
1D.

Garth

> if (d0 == 0 && d1 == 0)
> {
> std::vector<std::vector<std::size_t> >
> connectivity00(topology.size(0), std::vector<std::size_t>(1));
> for (MeshEntityIterator v(mesh, 0); !v.end(); ++v)
> connectivity00[v->index()][0] = v->index();
> topology(0, 0).set(connectivity00);
> }
>
> --
> You received this bug notification because you are a member of DOLFIN
> Core Team, which is subscribed to DOLFIN.
> https://bugs.launchpad.net/bugs/1143977
>
> Title:
> Dolfin mesh smoothing broken
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/dolfin/+bug/1143977/+subscriptions
>

--
Garth N. Wells
Department of Engineering, University of Cambridge
http://www.eng.cam.ac.uk/~gnw20

[Anders Logg (logg)]

On Tue, Mar 19, 2013 at 12:20:23AM -0000, Garth Wells wrote:
>> This is broken because someone broke the connectivity computation for
>> 0-0 connectivity. I found the following in TopologyComputation.cpp. It
>> just sets every vertex to be connected to itself. Why was this changed?
>>
>>
> This was discussed on the mailing list.
> It was changed because it makes a bunch of algorithms work in any
> dimension. Specifically, it was changed to make the parallel code work in
> 1D.

I worked around it by using vertex-edge connectivity.

--
Anders