mg_transfer_global_coarsening.cc

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// -----------------------------------------------------------------------------
//
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception OR LGPL-2.1-or-later
// Copyright (C) 2020 - 2025 by the deal.II authors
//
// This file is part of the deal.II library.
//
// Detailed license information governing the source code and contributions
// can be found in LICENSE.md and CONTRIBUTING.md at the top level directory.
//
// -----------------------------------------------------------------------------
 
#include <deal.II/multigrid/mg_transfer_global_coarsening.templates.h>
 
DEAL_II_NAMESPACE_OPEN
 
namespace MGTransferGlobalCoarseningTools
{
  unsigned int
  create_next_polynomial_coarsening_degree(
    const unsigned int                      previous_fe_degree,
    const PolynomialCoarseningSequenceType &p_sequence)
  {
    switch (p_sequence)
      {
        case PolynomialCoarseningSequenceType::bisect:
          return std::max(previous_fe_degree / 2, 1u);
        case PolynomialCoarseningSequenceType::decrease_by_one:
          return std::max(previous_fe_degree - 1, 1u);
        case PolynomialCoarseningSequenceType::go_to_one:
          return 1u;
        default:
          DEAL_II_NOT_IMPLEMENTED();
          return 1u;
      }
  }
 
 
 
  std::vector<unsigned int>
  create_polynomial_coarsening_sequence(
    const unsigned int                      max_degree,
    const PolynomialCoarseningSequenceType &p_sequence)
  {
    std::vector<unsigned int> degrees{max_degree};
 
    while (degrees.back() > 1)
      degrees.push_back(
        create_next_polynomial_coarsening_degree(degrees.back(), p_sequence));
 
    std::reverse(degrees.begin(), degrees.end());
 
    return degrees;
  }
} // namespace MGTransferGlobalCoarseningTools
 
#include "multigrid/mg_transfer_global_coarsening.inst"
 
DEAL_II_NAMESPACE_CLOSE