dolfin team mailing list archive

["Garth N. Wells" <g.n.wells@xxxxxxxxxx>]

Anders Logg wrote:
> On Tue, May 01, 2007 at 02:52:28PM +0200, Garth N. Wells wrote:
> > There appears to be a bug in
> >
> > ConstantFunction::interpolate(real* coefficients,
> >                                const ufc::cell& cell,
> >                                const ufc::finite_element& finite_element)
> >
> > as it always returns zeros. Should
> >
> >   // Evaluate each dof to get coefficients for nodal basis expansion
> >    for (uint i = 0; i < finite_element.space_dimension(); i++)
> >      coefficients[i] = finite_element.evaluate_dof(i, *this, cell);
> >
> > be
> >
> >   // Evaluate each dof to get coefficients for nodal basis expansion
> >    for (uint i = 0; i < finite_element.space_dimension(); i++)
> >      coefficients[i] = value;
> >
> > ?
> >
> > Garth
>
> No, it should be finite_element.evaluate_dof() since the constant
> value is not always equal to the value of the dof (but it is for
> Lagrange).
>
> I'll take a look and see if I can find the problem as soon as I get a
> chance.
>
> The call to evaluate_dof() should generate a call to the overloaded
> evaluate() function in ConstantFunction. (If you look in the code
> generated by FFC for evaluate_dof(), it should contain a call to
> evaluate().)

The problem is that FFC is generating

  /// Evaluate linear functional for dof i on the function f
  virtual double evaluate_dof(unsigned int i,
                              const ufc::function& f,
                              const ufc::cell& c) const
  {
    // Not implemented (only for Lagrange elements
    return 0;
  }

I'm using a discontinuous Lagrange element of order 0 for the time step 
dt. Can this easily be fixed for discontinuous Lagrange elements?

Also, could FFC generate an exception for functions which are not yet 
implemented?

Garth

> /Anders
>
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