itkSymmetricEigenSystem.txx

Go to the documentation of this file.

/*=========================================================================

  Program:   Insight Segmentation & Registration Toolkit
  Module:    $RCSfile: itkSymmetricEigenSystem.txx,v $
  Language:  C++
  Date:      $Date: 2007-03-22 21:39:38 $
  Version:   $Revision: 1.8 $

  Copyright (c) Insight Software Consortium. All rights reserved.
  See ITKCopyright.txt or http://www.itk.org/HTML/Copyright.htm for details.

     This software is distributed WITHOUT ANY WARRANTY; without even 
     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR 
     PURPOSE.  See the above copyright notices for more information.

=========================================================================*/
#ifndef __itkSymmetricEigenSystem_txx
#define __itkSymmetricEigenSystem_txx

#include "itkSymmetricEigenSystem.h"

namespace itk
{

template< class TMatrixElement, int VNumberOfRows >
SymmetricEigenSystem< TMatrixElement, VNumberOfRows >
::SymmetricEigenSystem()
{
  m_Matrix = 0;
  m_UseAbsoluteOrder = true;
  m_EigenValues.Fill( NumericTraits< TMatrixElement >::Zero );
  ArrayType temp;
  temp.Fill( NumericTraits< TMatrixElement >::Zero );
  m_EigenVectors.Fill(temp);
}

template< class TMatrixElement, int VNumberOfRows >
SymmetricEigenSystem< TMatrixElement, VNumberOfRows >
::~SymmetricEigenSystem()
{
}

template< class TMatrixElement, int VNumberOfRows >
void
SymmetricEigenSystem< TMatrixElement, VNumberOfRows >
::PrintSelf(std::ostream& os, Indent indent) const 
{
  Superclass::PrintSelf(os, indent);

  os << indent << "Matrix:";

  if ( m_Matrix != 0 )
    { 
    os << m_Matrix << std::endl;
    }
  else
    {
    os << "not set." << std::endl;
    }

  os << indent << "Eigen Vectors  " << m_EigenVectors << std::endl;
  os << indent << "Eigen Values   " << m_EigenValues << std::endl;
  os << indent << "Absolute order " << m_UseAbsoluteOrder << std::endl;
}


template< class TMatrixElement, int VNumberOfRows >
void
SymmetricEigenSystem< TMatrixElement, VNumberOfRows >
::GenerateData( void )
{
  int i, j, k;

  InternalEigenSystemType internalEigenSystem(m_Matrix->GetVnlMatrix());

  typedef vnl_vector< TMatrixElement > EigenVectorType; 
  EigenVectorType tempVector;

  for (i = 0; i < VNumberOfRows; i++)
    {
    tempVector = internalEigenSystem.get_eigenvector(i);
    m_EigenValues[i] = internalEigenSystem.get_eigenvalue(i);
    for (j = 0; j < VNumberOfRows; j++)
      {
      m_EigenVectors[i][j] = tempVector[j];
      }
    }

  double temp;
  for(i = 0; i < (VNumberOfRows - 1); i++)
    {
    for(j = i + 1; j < VNumberOfRows; j++)
      {
      if( (m_EigenValues[j] > m_EigenValues[i] && !m_UseAbsoluteOrder) ||
          ( (vnl_math_abs( m_EigenValues[j] ) > vnl_math_abs( m_EigenValues[i] ) ) 
            && m_UseAbsoluteOrder) )
        {
        temp= m_EigenValues[i];
        m_EigenValues[i] = m_EigenValues[j];
        m_EigenValues[j] = temp;
        for ( k = 0; k < VNumberOfRows; k++ )
          {
          temp = m_EigenVectors[i][k];
          m_EigenVectors[i][k] = m_EigenVectors[j][k];
          m_EigenVectors[j][k] = temp;
          }
        }
      }
    }
}

} // end namespace itk

#endif