tensor_utilities.h

/*  ______________________________________________________________________
 *
 *  ExaDG - High-Order Discontinuous Galerkin for the Exa-Scale
 *
 *  Copyright (C) 2021 by the ExaDG authors
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program. If not, see <https://www.gnu.org/licenses/>.
 *  ______________________________________________________________________
 */
 
#ifndef EXADG_UTILITIES_TENSOR_UTILITIES_H_
#define EXADG_UTILITIES_TENSOR_UTILITIES_H_
 
// C/C++
#include <memory>
 
// deal.II
#include <deal.II/base/tensor.h>
#include <deal.II/lac/vector.h>
 
namespace ExaDG
{
template<int n_components1, int n_components2, typename Number>
inline void
extract_component_from_tensors(
  dealii::Vector<Number> &                                                  dst,
  std::vector<dealii::Tensor<n_components1, n_components2, Number>> const & values,
  unsigned int const                                                        comp1,
  unsigned int const                                                        comp2)
{
  AssertIndexRange(comp1, n_components1);
  AssertIndexRange(comp2, n_components2);
 
  auto iter = dst.begin();
  for(auto const & val : values)
  {
    *iter = val[comp1][comp2];
    ++iter;
  }
}

template<int n_components, typename Number>
inline void
extract_component_from_tensors(dealii::Vector<Number> &                                     dst,
                               std::vector<dealii::Tensor<1, n_components, Number>> const & values,
                               unsigned int const                                           comp)
{
  AssertIndexRange(comp, n_components);
 
  auto iter = dst.begin();
  for(auto const & val : values)
  {
    *iter = val[comp];
    ++iter;
  }
}
 
template<int rank, int dim>
constexpr unsigned int
rank_to_n_components()
{
  return (rank == 0) ? 1 : ((rank == 1) ? dim : dealii::numbers::invalid_unsigned_int);
}
 
template<int n_components, int dim>
constexpr unsigned int
n_components_to_rank()
{
  return (n_components == 1) ? 0 :
                               ((n_components == dim) ? 1 : dealii::numbers::invalid_unsigned_int);
}
 
} // namespace ExaDG
 
#endif /* EXADG_UTILITIES_TENSOR_UTILITIES_H_ */