Comment 1 for bug 1082157

On reflection, perhaps it is correct after all. The diameter in
question is the diameter of the sphere with all four vertices on the
surface; i.e., it goes to infinite as the cell degenerates.

What the glyph scaling requires is really a measure of the
characteristic cell size; something with a reasonable maximum value
even in the presence of some bad cells in the mesh. It could be
incircle/insphere, or just longest side length. Is there a method to
calculate this for a (general) cell?

On 23 November 2012 08:08, Anders Logg <email address hidden> wrote:
> ** Changed in: dolfin
> Assignee: (unassigned) => Anders Logg (logg)
>
> ** Changed in: dolfin
> Importance: Undecided => Medium
>
> ** Changed in: dolfin
> Milestone: None => 1.1.0
>
> --
> You received this bug notification because you are a member of DOLFIN
> Team, which is subscribed to DOLFIN.
> https://bugs.launchpad.net/bugs/1082157
>
> Title:
> Bad cell diameter in gear mesh
>
> Status in DOLFIN:
> New
>
> Bug description:
> See https://bugs.launchpad.net/bugs/1034187.
>
> The mesh used in the elasticity demo
> (demo/undocumented/elasticity/python/gear.xml.gz) reports a very large
> hmax(). hmax() is reported as 36.001, but the whole mesh is smaller
> than 1 in all directions. Maybe related to numerical precision for
> nearly degenerate cells?
>
> from dolfin import *
> mesh = Mesh("gear.xml.gz")
>
> c = Cell(mesh, 18847)
> print c.diameter()
> # 36.001483031
>
> print c.volume()
> # 7.373890632542822e-11
>
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