identity_matrix.h

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// ------------------------------------------------------------------------
//
// SPDX-License-Identifier: LGPL-2.1-or-later
// Copyright (C) 2006 - 2022 by the deal.II authors
//
// This file is part of the deal.II library.
//
// Part of the source code is dual licensed under Apache-2.0 WITH
// LLVM-exception OR LGPL-2.1-or-later. Detailed license information
// governing the source code and code contributions can be found in
// LICENSE.md and CONTRIBUTING.md at the top level directory of deal.II.
//
// ------------------------------------------------------------------------
 
#ifndef dealii_identity_matrix_h
#define dealii_identity_matrix_h
 
 
#include <deal.II/base/config.h>
 
#include <deal.II/lac/exceptions.h>
 
DEAL_II_NAMESPACE_OPEN
 
class IdentityMatrix
{
public:
  using size_type = types::global_dof_index;
 
  IdentityMatrix();
 
  explicit IdentityMatrix(const size_type n);
 
  void
  reinit(const size_type n);
 
  size_type
  m() const;
 
  size_type
  n() const;
 
  template <typename OutVectorType, typename InVectorType>
  void
  vmult(OutVectorType &out, const InVectorType &in) const;
 
  template <typename OutVectorType, typename InVectorType>
  void
  vmult_add(OutVectorType &out, const InVectorType &in) const;
 
  template <typename OutVectorType, typename InVectorType>
  void
  Tvmult(OutVectorType &out, const InVectorType &in) const;
 
 
  template <typename OutVectorType, typename InVectorType>
  void
  Tvmult_add(OutVectorType &out, const InVectorType &in) const;
 
private:
  size_type size;
};
 
 
 
// ------------------------- inline and template functions -------------
#ifndef DOXYGEN
 
 
inline IdentityMatrix::IdentityMatrix()
  : size(0)
{}
 
 
 
inline IdentityMatrix::IdentityMatrix(const size_type n)
  : size(n)
{}
 
 
 
inline void
IdentityMatrix::reinit(const size_type n)
{
  size = n;
}
 
 
 
inline IdentityMatrix::size_type
IdentityMatrix::m() const
{
  return size;
}
 
 
 
inline IdentityMatrix::size_type
IdentityMatrix::n() const
{
  return size;
}
 
 
 
template <typename OutVectorType, typename InVectorType>
inline void
IdentityMatrix::vmult(OutVectorType &out, const InVectorType &in) const
{
  Assert(out.size() == size, ExcDimensionMismatch(out.size(), size));
  Assert(in.size() == size, ExcDimensionMismatch(in.size(), size));
 
  out = in;
}
 
 
 
template <typename OutVectorType, typename InVectorType>
inline void
IdentityMatrix::vmult_add(OutVectorType &out, const InVectorType &in) const
{
  Assert(out.size() == size, ExcDimensionMismatch(out.size(), size));
  Assert(in.size() == size, ExcDimensionMismatch(in.size(), size));
 
  out += in;
}
 
 
 
template <typename OutVectorType, typename InVectorType>
inline void
IdentityMatrix::Tvmult(OutVectorType &out, const InVectorType &in) const
{
  Assert(out.size() == size, ExcDimensionMismatch(out.size(), size));
  Assert(in.size() == size, ExcDimensionMismatch(in.size(), size));
 
  out = in;
}
 
 
 
template <typename OutVectorType, typename InVectorType>
inline void
IdentityMatrix::Tvmult_add(OutVectorType &out, const InVectorType &in) const
{
  Assert(out.size() == size, ExcDimensionMismatch(out.size(), size));
  Assert(in.size() == size, ExcDimensionMismatch(in.size(), size));
 
  out += in;
}
 
 
#endif
 
DEAL_II_NAMESPACE_CLOSE
 
#endif