identity_matrix.h

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// ---------------------------------------------------------------------
//
// Copyright (C) 2006 - 2018 by the deal.II authors
//
// This file is part of the deal.II library.
//
// The deal.II library is free software; you can use it, redistribute
// it, and/or modify it under the terms of the GNU Lesser General
// Public License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// The full text of the license can be found in the file LICENSE.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