[dune-fem] LocalFunctionAdapter

[Agnese, Marco]

Hi,
I am trying (without much success :)) to interpolate a c++ analytical function over a grid. 

So let's suppose that I have an identical function
RangeType f(const DomainType& x,const double& t,const EntityType& entity)
{
return x;
}

I have created the following class

template<typename DiscreteSpaceImp>
class LocalAnalyticalFunction
{
  public:
  typedef DiscreteSpaceImp DiscreteFunctionSpaceType;
  typedef typename DiscreteFunctionSpaceType::FunctionSpaceType FunctionSpaceType;
  typedef typename DiscreteFunctionSpaceType::GridPartType GridPartType;
  typedef typename DiscreteFunctionSpaceType::EntityType EntityType;

  typedef typename FunctionSpaceType::DomainType DomainType;
  typedef typename FunctionSpaceType::RangeType RangeType;

  typedef std::function<RangeType(const DomainType&,const double&,const EntityType&)> AnalyticalFunctionType;

  // constructor
  LocalAnalyticalFunction(const AnalyticalFunctionType& f,const double& t):
    f_(f),t_(t)
  {}

  // evaluate local function
  inline void evaluate(const DomainType& x,RangeType& val)
  {
    val=f_(entity().geometry().global(x),t_,entity());
  }

  // initialize to new entity
  inline void init(const EntityType& entity)
  { 
    entity_=&entity;
  }

  inline const EntityType& entity() const
  {
    return *entity_;
  }

  private:
  EntityType const * entity_;
  const AnalyticalFunctionType& f_;
  const double& t_;
};

Now I try to interpolate f() doing this

  typedef LocalAnalyticalFunction<DiscreteSpaceType> LocalAnalyticalFunctionType;
  LocalAnalyticalFunctionType localAnalyticalFunction(f,t);

  // create adapter
  typedef LocalFunctionAdapter<LocalAnalyticalFunctionType> AdaptedFunctionType;
  AdaptedFunctionType fAdapted("adapted function",localAnalyticalFunction,df.gridPart());

  interpolate(fAdapted,df);

where df is a discrete function defined over a LagrangeSpace.


The interpolate() function returns me the following error

no known conversion for argument 1 from ‘const Dune::Fem::QuadraturePointWrapper<Dune::Fem::CachingPointList<Dune::Fem::LeafGridPart<Dune::GeometryGrid<Dune::AlbertaGrid<2, 2>, Dune::Fem::VertexFunction<Dune::AlbertaGrid<2, 2> >, std::allocator<void> > >, 0, Dune::Fem::LagrangePointSetTraits<double, 2, 2u> > >’ to ‘const DomainType& {aka const Dune::FieldVector<double, 2>&}

therefore seems that it calls the evaluate() using a lagrange point as x which has a type different from DomainType. 

What I am doing wrong? I don't understand.  

Thank you very much for your help,
cheers,
Marco.