dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Tue, Dec 16, 2008 at 02:19:38PM +0000, Garth N. Wells wrote:
> 
> 
> Anders Logg wrote:
> > On Tue, Dec 16, 2008 at 02:20:22PM +0100, Martin Sandve Alnæs wrote:
> >> If I subclass Function and implement eval, then
> >> call vector() on an object of my class, a vector
> >> is created but initialized to zero. I would rather
> >> expect that the function is evaluated in the function space:
> >>
> >> GenericVector& Function::vector()
> >>  {
> >>    // Initialize vector of dofs if not initialized
> >>    if (!_vector)
> >> +  {
> >>      init();
> >> +    interpolate(*_vector, *_function_space);
> >> +  }
> >>
> >>    dolfin_assert(_vector);
> >>    return *_vector;
> >> }
> > 
> > Looks like a good idea. Can you add it?
> > 
> >> But I'm not sure what kind of side effects this can have on other code?
> >>
> >> Martin
> > 
> > I don't think it will have more side effects than what we have now
> > when we just create a zero vector.
> >
> 
> Interpolate is tricky because not all functions (e.g. DG) are 
> interpolated sensibly. This issue pops up in the VTK io.
> 
> Garth

I don't think that's a problem here. The interpolation will be into
the appropriate function space, which for a DG function is a DG space,
so for DG0, the vector will contain one value for each cell.

-- 
Anders

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