[dune-fem] Lagrange DG extract points

[Andreas Dedner]

Hi Macro.
It looks to me that you should use the natural interpolation of the 
space you have, i.e.,
evaluation at lagrange points for any of the Lagrange spaces or L^2 
projection for the
DiscontinousGalerkinSpace (using modal basis functions) etc.
Have a look at dune/fem/space/test/interpolation.hh
That should be much more general and much simpler....
Hope that helps
Andreas

On 17/04/15 15:16, Agnese, Marco wrote:
> Hi,
> I have a function f:x_global->y_global and I want to evaluate it in all the degree of freedom of a certain DiscreteSpace.
>
> If the space is of type LagrangeDiscreteFunctionSpace it is very simple:
> loop over the entities,
> extract the Lagrange points,
> apply function to the points,
> store the result.
>
> Instead, If the space is of type LagrangeDiscontinuousGalerkinSpace instead ,it is not possible to extract the Lagrange points.
> A workaround is to create a fake continuous Lagrange space to extract the points.
>
> I don't like very much this solution and I would prefer to have a consistent way to extract these points.
>
> Is it possible to add the method lagrangePointSet() also to the discontinuous space?
> I tried to look at the code of both spaces but they look pretty different therefore I need a little help and I can try to implement it by myself.
>
> Thank you,
> cheers,
> Marco.
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