refinedp0localbasis.hh

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// -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
// vi: set et ts=4 sw=2 sts=2:
// SPDX-FileCopyrightInfo: Copyright © DUNE Project contributors, see file LICENSE.md in module root
// SPDX-License-Identifier: LicenseRef-GPL-2.0-only-with-DUNE-exception
#ifndef DUNE_REFINED_P0_LOCALBASIS_HH
#define DUNE_REFINED_P0_LOCALBASIS_HH

#include <numeric>

#include <dune/common/fvector.hh>
#include <dune/common/fmatrix.hh>

#include <dune/localfunctions/common/localbasis.hh>
#include <dune/localfunctions/refined/common/refinedsimplexlocalbasis.hh>

namespace Dune
{

  template<class D, class R, int dim>
  class RefinedP0LocalBasis
    : public RefinedSimplexLocalBasis<D,dim>
  {
    // 2 to the k-th power
    constexpr static int N = 1<<dim;
  public:
    typedef LocalBasisTraits<D,dim,Dune::FieldVector<D,dim>,R,1,Dune::FieldVector<R,1>, Dune::FieldMatrix<R,1,dim> > Traits;

    unsigned int size () const
    {
      return N;
    }

    inline void evaluateFunction (const typename Traits::DomainType& in,
                                  std::vector<typename Traits::RangeType>& out) const
    {
      int subElement = this->getSubElement(in);
      out.resize(N);
      for(int i=0; i<N; ++i)
        out[i] = (i==subElement) ? 1 : 0;
    }

    inline void
    evaluateJacobian (const typename Traits::DomainType& in,         // position
                      std::vector<typename Traits::JacobianType>& out) const      // return value
    {
      out.resize(N);
      for(int i=0; i<N; ++i)
        out[i][0] = 0;
    }

    void partial (const std::array<unsigned int, dim>& order,
                  const typename Traits::DomainType& in,         // position
                  std::vector<typename Traits::RangeType>& out) const      // return value
    {
      auto totalOrder = std::accumulate(order.begin(), order.end(), 0);
      if (totalOrder == 0) {
        evaluateFunction(in, out);
      } else {
        out.resize(size());
        for (std::size_t i = 0; i < size(); ++i)
          out[i] = 0;
      }
    }

    unsigned int order () const
    {
      return 0;
    }

  };

}
#endif