[dune-fem] Hessian not implemented for DG shape function set

[Tobias Malkmus]

Hi Parvin

Sorry that you had to wait for a reply.

We had a major change in the acctual repository version ( trunk ).

Among many other changes we introduced the shapefunctionset,
which holds a set of base functions for the reference element.
Further we changed the baseFunctionSet into the basisFunctionSet.

If a space can provide a shapefunction set, a default wrapper class 
around this shapefunction set generates the basisFunctionSet.

So all work is done in the implementation of the shapefunctionSet.

To your Error:
For an orthonormal shapefunction set, the hessian method is not 
implmeneted, yet.

As far as i know, it was only implemented for d=2 and simplicial 
elements. For Legendre and Lagrange shapefunctions a hessian method 
should be implemented.

As a fast fix i can try to implement the case of triangls in 2d.

A general version for arbitrary dimensions and geometrical shapes  would 
need some more time and man power ( eg. you =) ).

Best Tobias



On 08/14/2013 12:15 AM, Pravin Madhavan wrote:
> Dear dune-fem community,
>
> I am working on the implementation of an a posteriori error estimator
> for a discontinuous Galerkin (DG) method on surfaces (world dimension =
> 3, grid dimension = 2). I have recently moved from the release versions
> of the dune modules (version 2.2.1) and the dune-fem module (version
> 1.3.1) to the latest respository version of the dune and dune-fem modules.
>
> In my code I compute the hessian of a local function u_h of a DG
> discrete function i.e. u_h.hessian( x, hess ). With the repository
> version of the modules I get the following compile time error:
>
> Error: NotImplemented
> [*hessianEach*:[...]/dune-fem/dune/fem/space/discontinuousgalerkin/*shapefunctionset.hh*:308]:
> Hessian not implemented for this shape function set.
>
> I was wondering why this method was not implemented and how I can go
> about implementing it. When using the release version of the dune
> modules, everything seems to be working fine and the *hessianAll* method
> in dune/fem/space/basefunctions/*basefunctionsetinterface.hh* is called
> instead. Is this method correctly implemented for my setting? Thank you.
>
> Best wishes,
> Pravin
>
>
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-- 
Tobias Malkmus                 <tomalk at mathematik.uni-freiburg.de>

Mathematisches Institut               Tel: +49 761 203 5627
Abt. für Angewandte Mathematik        Universität Freiburg
Hermann-Herder-Str. 10
79104 Freiburg