chromium/third_party/eigen3/src/Eigen/src/Core/PermutationMatrix.h

// This file is part of Eigen, a lightweight C++ template library
// for linear algebra.
//
// Copyright (C) 2009 Benoit Jacob <[email protected]>
// Copyright (C) 2009-2015 Gael Guennebaud <[email protected]>
//
// This Source Code Form is subject to the terms of the Mozilla
// Public License v. 2.0. If a copy of the MPL was not distributed
// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.

#ifndef EIGEN_PERMUTATIONMATRIX_H
#define EIGEN_PERMUTATIONMATRIX_H

// IWYU pragma: private
#include "./InternalHeaderCheck.h"

namespace Eigen {

namespace internal {

enum PermPermProduct_t { … };

}  // end namespace internal

/** \class PermutationBase
 * \ingroup Core_Module
 *
 * \brief Base class for permutations
 *
 * \tparam Derived the derived class
 *
 * This class is the base class for all expressions representing a permutation matrix,
 * internally stored as a vector of integers.
 * The convention followed here is that if \f$ \sigma \f$ is a permutation, the corresponding permutation matrix
 * \f$ P_\sigma \f$ is such that if \f$ (e_1,\ldots,e_p) \f$ is the canonical basis, we have:
 *  \f[ P_\sigma(e_i) = e_{\sigma(i)}. \f]
 * This convention ensures that for any two permutations \f$ \sigma, \tau \f$, we have:
 *  \f[ P_{\sigma\circ\tau} = P_\sigma P_\tau. \f]
 *
 * Permutation matrices are square and invertible.
 *
 * Notice that in addition to the member functions and operators listed here, there also are non-member
 * operator* to multiply any kind of permutation object with any kind of matrix expression (MatrixBase)
 * on either side.
 *
 * \sa class PermutationMatrix, class PermutationWrapper
 */
template <typename Derived>
class PermutationBase : public EigenBase<Derived> { … };

namespace internal {
traits<PermutationMatrix<SizeAtCompileTime, MaxSizeAtCompileTime, StorageIndex_>>;
}  // namespace internal

/** \class PermutationMatrix
 * \ingroup Core_Module
 *
 * \brief Permutation matrix
 *
 * \tparam SizeAtCompileTime the number of rows/cols, or Dynamic
 * \tparam MaxSizeAtCompileTime the maximum number of rows/cols, or Dynamic. This optional parameter defaults to
 * SizeAtCompileTime. Most of the time, you should not have to specify it. \tparam StorageIndex_ the integer type of the
 * indices
 *
 * This class represents a permutation matrix, internally stored as a vector of integers.
 *
 * \sa class PermutationBase, class PermutationWrapper, class DiagonalMatrix
 */
template <int SizeAtCompileTime, int MaxSizeAtCompileTime, typename StorageIndex_>
class PermutationMatrix
    : public PermutationBase<PermutationMatrix<SizeAtCompileTime, MaxSizeAtCompileTime, StorageIndex_> > { … };

namespace internal {
traits<Map<PermutationMatrix<SizeAtCompileTime, MaxSizeAtCompileTime, StorageIndex_>, PacketAccess_>>;
}  // namespace internal

Map<PermutationMatrix<SizeAtCompileTime, MaxSizeAtCompileTime, StorageIndex_>, PacketAccess_>;

template <typename IndicesType_>
class TranspositionsWrapper;
namespace internal {
traits<PermutationWrapper<IndicesType_>>;
}  // namespace internal

/** \class PermutationWrapper
 * \ingroup Core_Module
 *
 * \brief Class to view a vector of integers as a permutation matrix
 *
 * \tparam IndicesType_ the type of the vector of integer (can be any compatible expression)
 *
 * This class allows to view any vector expression of integers as a permutation matrix.
 *
 * \sa class PermutationBase, class PermutationMatrix
 */
template <typename IndicesType_>
class PermutationWrapper : public PermutationBase<PermutationWrapper<IndicesType_> > { … };

/** \returns the matrix with the permutation applied to the columns.
 */
template <typename MatrixDerived, typename PermutationDerived>
EIGEN_DEVICE_FUNC const Product<MatrixDerived, PermutationDerived, AliasFreeProduct> operator*(
    const MatrixBase<MatrixDerived>& matrix, const PermutationBase<PermutationDerived>& permutation) { … }

/** \returns the matrix with the permutation applied to the rows.
 */
template <typename PermutationDerived, typename MatrixDerived>
EIGEN_DEVICE_FUNC const Product<PermutationDerived, MatrixDerived, AliasFreeProduct> operator*(
    const PermutationBase<PermutationDerived>& permutation, const MatrixBase<MatrixDerived>& matrix) { … }

InverseImpl<PermutationType, PermutationStorage>;

template <typename Derived>
const PermutationWrapper<const Derived> MatrixBase<Derived>::asPermutation() const { … }

namespace internal {

template <>
struct AssignmentKind<DenseShape, PermutationShape> { … };

}  // end namespace internal

}  // end namespace Eigen

#endif  // EIGEN_PERMUTATIONMATRIX_H