mg_base.h

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// -----------------------------------------------------------------------------
//
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception OR LGPL-2.1-or-later
// Copyright (C) 1999 - 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.
//
// -----------------------------------------------------------------------------
 
#ifndef dealii_mg_base_h
#define dealii_mg_base_h
 
/*
 * This file contains some abstract base classes
 * used by Multigrid.
 */
 
#include <deal.II/base/config.h>
 
#include <deal.II/base/enable_observer_pointer.h>
#include <deal.II/base/observer_pointer.h>
 
#include <deal.II/lac/vector.h>
 
 
DEAL_II_NAMESPACE_OPEN
 
template <typename VectorType>
class MGMatrixBase : public EnableObserverPointer
{
public:
  /*
   * Virtual destructor.
   */
  virtual ~MGMatrixBase() override = default;
 
  virtual void
  vmult(const unsigned int level,
        VectorType        &dst,
        const VectorType  &src) const = 0;
 
  virtual void
  vmult_add(const unsigned int level,
            VectorType        &dst,
            const VectorType  &src) const = 0;
 
  virtual void
  Tvmult(const unsigned int level,
         VectorType        &dst,
         const VectorType  &src) const = 0;
 
  virtual void
  Tvmult_add(const unsigned int level,
             VectorType        &dst,
             const VectorType  &src) const = 0;
 
  virtual unsigned int
  get_minlevel() const = 0;
 
  virtual unsigned int
  get_maxlevel() const = 0;
};
 
 
template <typename VectorType>
class MGCoarseGridBase : public EnableObserverPointer
{
public:
  virtual ~MGCoarseGridBase() override = default;
 
  virtual void
  operator()(const unsigned int level,
             VectorType        &dst,
             const VectorType  &src) const = 0;
};
 
 
template <typename VectorType>
class MGTransferBase : public EnableObserverPointer
{
public:
  virtual ~MGTransferBase() override = default;
 
  virtual void
  prolongate(const unsigned int to_level,
             VectorType        &dst,
             const VectorType  &src) const = 0;
 
  virtual void
  prolongate_and_add(const unsigned int to_level,
                     VectorType        &dst,
                     const VectorType  &src) const;
 
  virtual void
  restrict_and_add(const unsigned int from_level,
                   VectorType        &dst,
                   const VectorType  &src) const = 0;
};
 
 
 
template <typename VectorType>
class MGSmootherBase : public EnableObserverPointer
{
public:
  virtual ~MGSmootherBase() override = default;
 
  virtual void
  clear() = 0;
 
  virtual void
  smooth(const unsigned int level,
         VectorType        &u,
         const VectorType  &rhs) const = 0;
 
  virtual void
  apply(const unsigned int level, VectorType &u, const VectorType &rhs) const;
};
 
DEAL_II_NAMESPACE_CLOSE
 
#endif