ufl team mailing list archive

[Kent-Andre Mardal <kent-and@xxxxxxxxx>]

tor, 01.11.2007 kl. 22.43 +0100, skrev Anders Logg:
> On Thu, Nov 01, 2007 at 09:00:05AM +0100, kent-and@xxxxxxxxx wrote:
> > > 2007/11/1, Anders Logg <logg@xxxxxxxxx>:
> > >> On Tue, Oct 30, 2007 at 09:57:18AM +0100, Martin Sandve Alnæs wrote:
> > >> > 2007/10/29, Anders Logg <logg@xxxxxxxxx>:
> > >> > > On Fri, Oct 26, 2007 at 01:23:11PM +0200, Kent-Andre Mardal wrote:
> > >> > > > fre, 26.10.2007 kl. 12.09 +0200, skrev Martin Sandve Alnæs:
> > >> > > > > Den 25.10.07 skrev kent-and@xxxxxxxxx <kent-and@xxxxxxxxx>
> > >> følgende:
> > >> > > > > > geometry_element = FiniteElement("Hermite", "triangle", 3)
> > >> > > > > > uknown_element = FiniteElement("Lagrange", "triangle", 1,
> > >> geometry_element)
> > >> > > > >
> > >> > > > > Eller:
> > >> > > > >
> > >> > > > > cell = Cell(polygon, mapping="affine", order=1)
> > >> > > > > cell = Cell("triangle")
> > >> > > > > cell = Cell("triangle", "affine")
> > >> > > > > cell = Cell("triangle", "Hermite", 3)
> > >> > > > > cell = Cell("triangle", "isoparametric", 2)
> > >> > > > >
> > >> > > > > element = FiniteElement("Lagrange", cell, 1)
> > >> > > > > element = FiniteElement("Hermite", cell, 3)
> > >> > > >
> > >> > > > What we typically do is that we define the global element in terms
> > >> of a
> > >> > > > mapped reference element (as we know this is not always a smart
> > >> thing to
> > >> > > > do cf. the Rannacher-Turek element).
> > >> > > >
> > >> > > > Anyway, we could then have
> > >> > > >
> > >> > > > reference_element = ReferenceElement("Lagrange", "triangle", 3)
> > >> > > >
> > >> > > > mapping = Mapping("isoparametric", 3)
> > >> > > >
> > >> > > > global_element = FiniteElement(reference_element, mapping)
> > >> > > >
> > >> > > >
> > >> > > > Here Mapping could be e.g. affine, Piola, isoparametric, Hermite
> > >> > > >
> > >> > > >
> > >> > > > The short cut can be
> > >> > > >
> > >> > > > fe = FiniteElement("Lagrange", "triangle", "affine", 3)
> > >> > >
> > >> > > Looks good to me, but it would be good to have the mapping as the
> > >> last
> > >> > > argument (so it could be left out when using the default mapping).
> > >> > >
> > >> > > /Anders
> > >> >
> > >> > The backside is that we must use FiniteElement.__init__(self, *args,
> > >> > **kwargs) to enable different constructor arguments in Python, I'm not
> > >> > a big fan of that. It would be nice to avoid that if we can.
> > >>
> > >> Why? Isn't it enought do do
> > >>
> > >>   def __init__(family, shape, degree, mapping="affine"):
> > >>       ...
> > >>
> > >> /Anders
> > >
> > >
> > > This doesn't fit into that exactly:
> > >
> > >> > reference_element = ReferenceElement("Lagrange", "triangle", 3)
> > >> > mapping = Mapping("isoparametric", 3)
> > >> > global_element = FiniteElement(reference_element, mapping)
> > >
> > >
> > 
> > OK, I think
> > 
> > cell = Cell(polygon, geometry="Lagrange", order=1)
> > element = FiniteElement("Lagrange", cell, 1, geometry_mapping="affine")
> 
> It seems more natural to put the information about the type of mapping
> in the mapping argument. It looks like it's now in two places (cell
> and geometry_mapping)?
> 
> /Anders

But it may be two separate things. First, the mapping of the geometry
from the reference geometry to the global geometry. Then the mapping 
of the basis functions from the reference element to the global
element.  

Kent