dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Thu, Sep 16, 2010 at 01:27:07PM -0700, Johan Hake wrote:
> On Thursday September 16 2010 13:15:51 Anders Logg wrote:
> > On Thu, Sep 16, 2010 at 01:10:55PM -0700, Johan Hake wrote:
> > > On Thursday September 16 2010 13:03:44 Anders Logg wrote:
> > > > On Thu, Sep 16, 2010 at 12:51:28PM -0700, Johan Hake wrote:
> > > > > On Thursday September 16 2010 12:27:57 Anders Logg wrote:
> > > > > > On Thu, Sep 16, 2010 at 12:23:48PM -0700, Johan Hake wrote:
> > > > > > > On Thursday September 16 2010 11:46:02 Anders Logg wrote:
> > > > > > > > On Thu, Sep 16, 2010 at 11:24:34AM -0700, Johan Hake wrote:
> > > > > > > > > Hello!
> > > > > > > > >
> > > > > > > > > I added the method area to the Face class. I guess a Face is
> > > > > > > > > always a triangle so it should be safe.
> > > > > > > >
> > > > > > > > Yes.
> > > > > > >
> > > > > > > ok
> > > > > > >
> > > > > > > > > There might be other methods that can be usefull like
> > > > > > > > > normal? Others?
> > > > > > > >
> > > > > > > > Probably but can't think of any more right now.
> > > > > > > >
> > > > > > > > > Should we do the same for Facet, but then check for
> > > > > > > > > topological dimension before making the computation, a la
> > > > > > > > > the generalized volume in CellTypes?
> > > > > > > >
> > > > > > > > Facet should have normal but not area.
> > > > > > >
> > > > > > > I wont add these now. I first thought they were straight forward,
> > > > > > > but all kindoff R^1, R^2, R^3 stuff needs to be checked for.
> > > > > > > Leave it for now...
> > > > > > >
> > > > > > > Added a blueprint!
> > > > > >
> > > > > > I thought I already did that. We have Cell.normal() which should
> > > > > > handle that.
> > > > >
> > > > > That just calls normal of TriangleCell or TetrahedronCell.
> > > > > TriangleCell only returns a normal for topological dimension 2.
> > > >
> > > > Isn't that enough? What else do you need?
> > >
> > > For a Face I need to check if it is in R^2 or R^3.
> > >
> > > > > It is really not difficult, it just took some more time than I
> > > > > anticipated, and I do not need the feature. I just needed area :)
> > > >
> > > > Oh so you didn't need anything else. ;-)
> > >
> > > Nope! Not for the moment.
> > >
> > > But now it is at least straight forward to iterate over faces of a 3D
> > > mesh and calculate the area of a certain boundary domain given by a
> > > MeshFunction :)
> >
> > Perhaps we could have
> >
> >   double::Mesh::area(const FacetFunction& boundary_markers, uint boundary)
> > const;
>
> +
>
> Why not add a volume method while at it? Maybe we should let these be free
> functions as it does not always make sense to get an area or volume of a mesh?

I don't know what the dimension-independent terms are but most people
would probably accept "area" as meaning the length of the boundary of
a 2D domain.

--
Anders