identity_matrix.h

// ---------------------------------------------------------------------
//
// Copyright (C) 2006 - 2017 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 at
// the top level of the deal.II distribution.
//
// ---------------------------------------------------------------------

#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:
  typedef types::global_dof_index size_type;

  IdentityMatrix ();

  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