dolfin team mailing list archive

[Kristian Ølgaard <k.b.oelgaard@xxxxxxxxx>]

On 16 September 2010 22:45, Johan Hake <johan.hake@xxxxxxxxx> wrote:
> On Thursday September 16 2010 13:33:03 Anders Logg wrote:
>> 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.
>
> If I had a 2D mesh and it had a method area, I would definetly think that it
> would return the area of that mesh. But that might be just me...

Anders is talking about the area of Face/Facet of a 2D mesh which is
where this discussion originated from.

Kristian

> Johan
>>
>> --
>> Anders
>
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