ffc team mailing list archive

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

On 29 January 2010 21:12, Anders Logg <logg@xxxxxxxxx> wrote:
> On Fri, Jan 29, 2010 at 09:08:44PM +0100, Kristian Oelgaard wrote:
> > On 29 January 2010 20:21, Anders Logg <logg@xxxxxxxxx> wrote:
> > >On Fri, Jan 29, 2010 at 04:13:13PM +0100, Kristian Oelgaard wrote:
> > >>I think it is almost there, but we need to rethink the way we
> > >>manipulate the degrees of finite elements and forms, I think we have
> > >>discussed this before but I don't recall if we ever reached a
> > >>conclusion.  Try running the QuadratureElement.ufl demo.
> > >
> > >I don't see exactly what the problem is. Is it the automatic degree
> > >selection?
> > >
> > >I've added some more debug output and the following is now printed for
> > >the QuadratureElement demo:
> > >
> > > Found quadrature element(s) with the following degree(s): [3]
> > > Selecting quadrature degree based on quadrature element: 3
> > > quadrature_degree: auto --> 3
> > >
> > >That looks correct to me. Shouldn't this result in the same points
> > >being chosen for both the QuadratureElement and the quadrature loop?
> >
> > I see now that it is only a problem for tensor representation. For
> > the linear form the first term v*u*dx makes it a form of degree 4,
> > and tensor representation will use that degree for the entire form
> > if I remember correctly?
>
> Yes, and that's not much of a problem since it happens at compile
> time.

It is a problem if you try to tabulate a QuadratureElement with the wrong number of points :)

> But for the FFC demo the representation is chosen as quadrature since
> it involves quadrature elements, so if it fails it shouldn't be
> related to tensor representation?

Yes, for the bilinear form, for the linear form tensor is chosen, the degree is set to 4 and the problems begin.

File "/home/oelgaard/software/fenics_branches/dev/ffc/tensor/monomialintegration.py", line 101, in _init_table
   table[(ufl_element, None)] = fiat_element.tabulate(order, points)
 File "/home/oelgaard/software/fenics_branches/dev/ffc/mixedelement.py", line 77, in tabulate
   table = element.tabulate(order, points)
 File "/home/oelgaard/software/fenics_branches/dev/ffc/quadratureelement.py", line 104, in tabulate
   error("Points must be equal to coordinates of quadrature points")
 File "<string>", line 1, in <lambda>
 File "/home/oelgaard/software/fenics/ufl/ufl/log.py", line 124, in error
   raise UFLException(self._format_raw(*message))
ufl.log.UFLException: Points must be equal to coordinates of quadrature points

Kristian

> --
> Anders
>
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