// This file is part of Eigen, a lightweight C++ template library
// for linear algebra. Eigen itself is part of the KDE project.
//
// Copyright (C) 2006-2008 Benoit Jacob <jacob@math.jussieu.fr>
//
// Eigen is free software; you can 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 3 of the License, or (at your option) any later version.
//
// Alternatively, you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of 
// the License, or (at your option) any later version.
//
// Eigen is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License or the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public 
// License and a copy of the GNU General Public License along with
// Eigen. If not, see <http://www.gnu.org/licenses/>.

#ifndef EIGEN_SCALARMULTIPLE_H
#define EIGEN_SCALARMULTIPLE_H

/** \class ScalarMultiple
  *
  * \brief Expression of the product of a matrix or vector by a scalar
  *
  * \param FactorTye the type of scalar by which to multiply
  * \param MatrixType the type of the matrix or vector to multiply
  *
  * This class represents an expression of the product of a matrix or vector by a scalar.
  * It is the return type of the operator* between a matrix or vector and a scalar, and most
  * of the time this is the only way it is used.
  */
template<typename MatrixType> class ScalarMultiple : NoOperatorEquals,
  public MatrixBase<typename MatrixType::Scalar, ScalarMultiple<MatrixType> >
{
  public:
    typedef typename MatrixType::Scalar Scalar;
    typedef typename MatrixType::Ref MatRef;
    friend class MatrixBase<Scalar, ScalarMultiple>;
    typedef MatrixBase<Scalar, ScalarMultiple> Base;

    ScalarMultiple(const MatRef& matrix, Scalar factor)
      : m_matrix(matrix), m_factor(factor) {}

  private:
    enum {
      RowsAtCompileTime = MatrixType::Traits::RowsAtCompileTime,
      ColsAtCompileTime = MatrixType::Traits::ColsAtCompileTime,
      MaxRowsAtCompileTime = MatrixType::Traits::MaxRowsAtCompileTime,
      MaxColsAtCompileTime = MatrixType::Traits::MaxColsAtCompileTime
    };

    const ScalarMultiple& _ref() const { return *this; }
    int _rows() const { return m_matrix.rows(); }
    int _cols() const { return m_matrix.cols(); }

    Scalar _coeff(int row, int col) const
    {
      return m_factor * m_matrix.coeff(row, col);
    }

  protected:
    const MatRef m_matrix;
    const Scalar m_factor;
};

/** relates MatrixBase sa class ScalarMultiple */                    
template<typename Scalar, typename Derived>                            
const ScalarMultiple<Derived>                              
MatrixBase<Scalar, Derived>::operator*(const Scalar& scalar) const                                          
{                                                                      
  return ScalarMultiple<Derived>(ref(), scalar);    
}                                                                      
                                                                                                                                              
/** \relates MatrixBase \sa class ScalarMultiple */                    
template<typename Scalar, typename Derived>                            
const ScalarMultiple<Derived> 
MatrixBase<Scalar, Derived>::operator/(const Scalar& scalar) const                                          
{                                                                      
  assert(NumTraits<Scalar>::HasFloatingPoint);                         
  return ScalarMultiple<Derived>(ref(), static_cast<Scalar>(1) / scalar);                                     
}
                                                                       
/** \sa ScalarMultiple */                                        
template<typename Scalar, typename Derived>                            
Derived&                                                              
MatrixBase<Scalar, Derived>::operator*=(const Scalar& other)       
{                                                                      
  return *this = *this * other;                                        
}                                                                      
                                                                       
/** \sa ScalarMultiple */                                        
template<typename Scalar, typename Derived>                            
Derived&                                                              
MatrixBase<Scalar, Derived>::operator/=(const Scalar& other)       
{                                                                      
  return *this = *this / other;                                        
}

#endif // EIGEN_SCALARMULTIPLE_H