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// 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_DIAGONALCOEFFS_H
#define EIGEN_DIAGONALCOEFFS_H
/** \class DiagonalCoeffs
*
* \brief Expression of the main diagonal of a square matrix
*
* \param MatrixType the type of the object in which we are taking the main diagonal
*
* This class represents an expression of the main diagonal of a square matrix.
* It is the return type of MatrixBase::diagonal() and most of the time this is
* the only way it is used.
*
* \sa MatrixBase::diagonal()
*/
template<typename MatrixType> class DiagonalCoeffs
: public MatrixBase<typename MatrixType::Scalar, DiagonalCoeffs<MatrixType> >
{
public:
typedef typename MatrixType::Scalar Scalar;
typedef typename MatrixType::Ref MatRef;
friend class MatrixBase<Scalar, DiagonalCoeffs>;
typedef MatrixBase<Scalar, DiagonalCoeffs> Base;
DiagonalCoeffs(const MatRef& matrix) : m_matrix(matrix) {}
EIGEN_INHERIT_ASSIGNMENT_OPERATORS(DiagonalCoeffs)
private:
enum {
RowsAtCompileTime = MatrixType::Traits::SizeAtCompileTime == Dynamic ? Dynamic
: EIGEN_ENUM_MIN(MatrixType::Traits::RowsAtCompileTime,
MatrixType::Traits::ColsAtCompileTime),
ColsAtCompileTime = 1,
MaxRowsAtCompileTime = MatrixType::Traits::MaxSizeAtCompileTime == Dynamic ? Dynamic
: EIGEN_ENUM_MIN(MatrixType::Traits::MaxRowsAtCompileTime,
MatrixType::Traits::MaxColsAtCompileTime),
MaxColsAtCompileTime = 1
};
const DiagonalCoeffs& _ref() const { return *this; }
int _rows() const { return std::min(m_matrix.rows(), m_matrix.cols()); }
int _cols() const { return 1; }
Scalar& _coeffRef(int row, int)
{
return m_matrix.coeffRef(row, row);
}
Scalar _coeff(int row, int) const
{
return m_matrix.coeff(row, row);
}
protected:
MatRef m_matrix;
};
/** \returns an expression of the main diagonal of *this, which must be a square matrix.
*
* Example: \include MatrixBase_diagonal.cpp
* Output: \verbinclude MatrixBase_diagonal.out
*
* \sa class DiagonalCoeffs */
template<typename Scalar, typename Derived>
DiagonalCoeffs<Derived>
MatrixBase<Scalar, Derived>::diagonal()
{
return DiagonalCoeffs<Derived>(ref());
}
/** This is the const version of diagonal(). */
template<typename Scalar, typename Derived>
const DiagonalCoeffs<Derived>
MatrixBase<Scalar, Derived>::diagonal() const
{
return DiagonalCoeffs<Derived>(ref());
}
#endif // EIGEN_DIAGONALCOEFFS_H
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