hierarchicallagrangebasis.hh

// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
 
// SPDX-FileCopyrightText: Copyright © DUNE Project contributors, see file AUTHORS.md
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception OR LGPL-3.0-or-later
 
#ifndef DUNE_FUNCTIONS_FUNCTIONSPACEBASES_HIERARCHICALLAGRANGEBASIS_HH
#define DUNE_FUNCTIONS_FUNCTIONSPACEBASES_HIERARCHICALLAGRANGEBASIS_HH
 
#include <type_traits>
 
#include <dune/common/exceptions.hh>
 
#include <dune/localfunctions/hierarchical/hierarchicalp2.hh>
 
#include <dune/functions/functionspacebases/nodes.hh>
#include <dune/functions/functionspacebases/defaultglobalbasis.hh>
#include <dune/functions/functionspacebases/lfeprebasismixin.hh>
 
#include <dune/geometry/type.hh>
 
namespace Dune {
  namespace Functions {
 
    // *****************************************************************************
    // Implementation for Hierarchical Lagrange Basis
    //
    // - only orders k=1,2 are implemented up to now
    // - order k=1 is identical to the standard Lagrange basis
    // - implementation is restricted to simplex grids
    //
    // *****************************************************************************
 
    template<typename GV, int k, typename R = double>
    class HierarchicalLagrangePreBasis;
 
    template<typename GV, typename R>
    class HierarchicalLagrangePreBasis<GV,1,R>
        : public LFEPreBasisMixin<GV, LagrangeSimplexLocalFiniteElement<typename GV::ctype,R,GV::dimension,1>>
    {
      using Base = LFEPreBasisMixin<GV, LagrangeSimplexLocalFiniteElement<typename GV::ctype,R,GV::dimension,1>>;
    public:
      HierarchicalLagrangePreBasis (const GV& gridView) :
        Base(gridView, [](GeometryType gt, int) -> std::size_t { return gt.isVertex() ? 1 : 0; })
      {
        for (auto gt : gridView.indexSet().types(0)) {
          if (!gt.isSimplex())
            DUNE_THROW(Dune::NotImplemented,
              "Hierarchical Lagrange basis only implemented for simplex grids.");
        }
      }
    };
 
    template<typename GV, typename R>
    class HierarchicalLagrangePreBasis<GV,2,R>
        : public LFEPreBasisMixin<GV, HierarchicalP2LocalFiniteElement<typename GV::ctype,R,GV::dimension>>
    {
      using Base = LFEPreBasisMixin<GV, HierarchicalP2LocalFiniteElement<typename GV::ctype,R,GV::dimension>>;
    public:
      HierarchicalLagrangePreBasis (const GV& gridView) :
        Base(gridView, [](GeometryType gt, int) -> std::size_t { return (gt.isVertex() || gt.isLine()) ? 1 : 0; })
      {
        for (auto gt : gridView.indexSet().types(0)) {
          if (!gt.isSimplex())
            DUNE_THROW(Dune::NotImplemented,
              "Hierarchical Lagrange basis only implemented for simplex grids.");
        }
      }
    };
 
 
    namespace BasisFactory {
 
      template<int k, typename R=double>
      auto hierarchicalLagrange()
      {
        static_assert(0 < k && k <= 2);
        return [](const auto& gridView) {
          return HierarchicalLagrangePreBasis<std::decay_t<decltype(gridView)>, k, R>(gridView);
        };
      }
 
    } // end namespace BasisFactory
 
    template<typename GV, int k, typename R=double>
    using HierarchicalLagrangeBasis = DefaultGlobalBasis<HierarchicalLagrangePreBasis<GV, k, R> >;
 
  } // end namespace Functions
} // end namespace Dune
 
#endif // DUNE_FUNCTIONS_FUNCTIONSPACEBASES_HIERARCHICALLAGRANGEBASIS_HH