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// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2009 Benoit Jacob <jacob.benoit.1@gmail.com>
//
// 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_PERMUTATIONMATRIX_H
#define EIGEN_PERMUTATIONMATRIX_H
/** \nonstableyet
* \class PermutationMatrix
*
* \brief Permutation matrix
*
* \param SizeAtCompileTime the number of rows/cols, or Dynamic
* \param MaxSizeAtCompileTime the maximum number of rows/cols, or Dynamic. This optional parameter defaults to SizeAtCompileTime.
*
* This class represents a permutation matrix, internally stored as a vector of integers.
* The convention followed here is the same as on <a href="http://en.wikipedia.org/wiki/Permutation_matrix">Wikipedia</a>,
* namely: the matrix of permutation \a p is the matrix such that on each row \a i, the only nonzero coefficient is
* in column p(i).
*
* \sa class DiagonalMatrix
*/
template<int SizeAtCompileTime, int MaxSizeAtCompileTime = SizeAtCompileTime> class PermutationMatrix;
template<typename PermutationType, typename MatrixType, int Side> struct ei_permut_matrix_product_retval;
template<int SizeAtCompileTime, int MaxSizeAtCompileTime>
struct ei_traits<PermutationMatrix<SizeAtCompileTime, MaxSizeAtCompileTime> >
: ei_traits<Matrix<int,SizeAtCompileTime,SizeAtCompileTime,0,MaxSizeAtCompileTime,MaxSizeAtCompileTime> >
{};
template<int SizeAtCompileTime, int MaxSizeAtCompileTime>
class PermutationMatrix : public AnyMatrixBase<PermutationMatrix<SizeAtCompileTime, MaxSizeAtCompileTime> >
{
public:
typedef ei_traits<PermutationMatrix> Traits;
typedef Matrix<int,SizeAtCompileTime,SizeAtCompileTime,0,MaxSizeAtCompileTime,MaxSizeAtCompileTime>
DenseMatrixType;
enum {
Flags = Traits::Flags,
CoeffReadCost = Traits::CoeffReadCost,
RowsAtCompileTime = Traits::RowsAtCompileTime,
ColsAtCompileTime = Traits::ColsAtCompileTime,
MaxRowsAtCompileTime = Traits::MaxRowsAtCompileTime,
MaxColsAtCompileTime = Traits::MaxColsAtCompileTime
};
typedef typename Traits::Scalar Scalar;
typedef Matrix<int, RowsAtCompileTime, 1, 0, MaxRowsAtCompileTime, 1> IndicesType;
inline PermutationMatrix()
{
}
template<int OtherSize, int OtherMaxSize>
inline PermutationMatrix(const PermutationMatrix<OtherSize, OtherMaxSize>& other)
: m_indices(other.indices()) {}
/** copy constructor. prevent a default copy constructor from hiding the other templated constructor */
inline PermutationMatrix(const PermutationMatrix& other) : m_indices(other.indices()) {}
/** generic constructor from expression of the indices */
template<typename Other>
explicit inline PermutationMatrix(const MatrixBase<Other>& other) : m_indices(other)
{}
template<int OtherSize, int OtherMaxSize>
PermutationMatrix& operator=(const PermutationMatrix<OtherSize, OtherMaxSize>& other)
{
m_indices = other.indices();
return *this;
}
/** This is a special case of the templated operator=. Its purpose is to
* prevent a default operator= from hiding the templated operator=.
*/
PermutationMatrix& operator=(const PermutationMatrix& other)
{
m_indices = other.m_indices();
return *this;
}
inline PermutationMatrix(int rows, int cols) : m_indices(rows)
{
ei_assert(rows == cols);
}
/** \returns the number of columns */
inline int rows() const { return m_indices.size(); }
/** \returns the number of rows */
inline int cols() const { return m_indices.size(); }
template<typename DenseDerived>
void evalTo(MatrixBase<DenseDerived>& other) const
{
other.setZero();
for (int i=0; i<rows();++i)
other.coeffRef(i,m_indices.coeff(i)) = typename DenseDerived::Scalar(1);
}
DenseMatrixType toDenseMatrix() const
{
return *this;
}
const IndicesType& indices() const { return m_indices; }
IndicesType& indices() { return m_indices; }
protected:
IndicesType m_indices;
};
/** \returns the matrix with the permutation applied to the columns.
*/
template<typename Derived, int SizeAtCompileTime, int MaxSizeAtCompileTime>
inline const ei_permut_matrix_product_retval<PermutationMatrix<SizeAtCompileTime, MaxSizeAtCompileTime>, Derived, OnTheRight>
operator*(const MatrixBase<Derived>& matrix,
const PermutationMatrix<SizeAtCompileTime, MaxSizeAtCompileTime> &permutation)
{
return ei_permut_matrix_product_retval
<PermutationMatrix<SizeAtCompileTime, MaxSizeAtCompileTime>, Derived, OnTheRight>
(permutation, matrix.derived());
}
/** \returns the matrix with the permutation applied to the rows.
*/
template<typename Derived, int SizeAtCompileTime, int MaxSizeAtCompileTime>
inline const ei_permut_matrix_product_retval
<PermutationMatrix<SizeAtCompileTime, MaxSizeAtCompileTime>, Derived, OnTheLeft>
operator*(const PermutationMatrix<SizeAtCompileTime, MaxSizeAtCompileTime> &permutation,
const MatrixBase<Derived>& matrix)
{
return ei_permut_matrix_product_retval
<PermutationMatrix<SizeAtCompileTime, MaxSizeAtCompileTime>, Derived, OnTheLeft>
(permutation, matrix.derived());
}
template<typename PermutationType, typename MatrixType, int Side>
struct ei_traits<ei_permut_matrix_product_retval<PermutationType, MatrixType, Side> >
{
typedef typename MatrixType::PlainMatrixType ReturnMatrixType;
};
template<typename PermutationType, typename MatrixType, int Side>
struct ei_permut_matrix_product_retval
: public ReturnByValue<ei_permut_matrix_product_retval<PermutationType, MatrixType, Side> >
{
typedef typename ei_cleantype<typename MatrixType::Nested>::type MatrixTypeNestedCleaned;
ei_permut_matrix_product_retval(const PermutationType& perm, const MatrixType& matrix)
: m_permutation(perm), m_matrix(matrix)
{}
inline int rows() const { return m_matrix.rows(); }
inline int cols() const { return m_matrix.cols(); }
template<typename Dest> inline void evalTo(Dest& dst) const
{
const int n = Side==OnTheLeft ? rows() : cols();
for(int i = 0; i < n; ++i)
{
Block<
Dest,
Side==OnTheLeft ? 1 : Dest::RowsAtCompileTime,
Side==OnTheRight ? 1 : Dest::ColsAtCompileTime
>(dst, Side==OnTheRight ? m_permutation.indices().coeff(i) : i)
=
Block<
MatrixTypeNestedCleaned,
Side==OnTheLeft ? 1 : MatrixType::RowsAtCompileTime,
Side==OnTheRight ? 1 : MatrixType::ColsAtCompileTime
>(m_matrix, Side==OnTheLeft ? m_permutation.indices().coeff(i) : i);
}
}
protected:
const PermutationType& m_permutation;
const typename MatrixType::Nested m_matrix;
};
#endif // EIGEN_PERMUTATIONMATRIX_H
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