dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

Harish Narayanan wrote:
> Anders Logg wrote:
> > No, it has not been implemented yet but it's something we desperately
> > need. If we define the L2 projection Pu of u onto V by
> >
> >   (Pu, v) = (u, v) for all v in V
> >
> > then the problem is in evaluating the integral on the right-hand side:
> >
> >   (u, v)
> >
> > where now u and v are defined on different meshes.
> >
> > My suggestion would be to evaluate this by quadrature at run-time,
> > using the generated UFC function
> >
> >   evaluate_basis
> >
> > and IntersectionDetector/GTS which is very fast at finding the overlap
> > between cells.
>
> Hmm, ok. I will try to compute the integral on the right-hands at 
> runtime using quadrature and use it to determine Pu.

It might be useful to look at

  DiscreteFunction::eval(real* values, const real* x) const

It uses some of what you'll need.

Garth


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