1 | // This file is part of Eigen, a lightweight C++ template library
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2 | // for linear algebra.
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3 | //
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4 | // Copyright (C) 2006-2008 Benoit Jacob <jacob.benoit.1@gmail.com>
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5 | // Copyright (C) 2009 Ricard Marxer <email@ricardmarxer.com>
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6 | // Copyright (C) 2009-2010 Gael Guennebaud <gael.guennebaud@inria.fr>
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7 | //
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8 | // This Source Code Form is subject to the terms of the Mozilla
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9 | // Public License v. 2.0. If a copy of the MPL was not distributed
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10 | // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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11 |
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12 | #ifndef EIGEN_REVERSE_H
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13 | #define EIGEN_REVERSE_H
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14 |
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15 | namespace Eigen {
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16 |
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17 | /** \class Reverse
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18 | * \ingroup Core_Module
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19 | *
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20 | * \brief Expression of the reverse of a vector or matrix
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21 | *
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22 | * \param MatrixType the type of the object of which we are taking the reverse
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23 | *
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24 | * This class represents an expression of the reverse of a vector.
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25 | * It is the return type of MatrixBase::reverse() and VectorwiseOp::reverse()
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26 | * and most of the time this is the only way it is used.
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27 | *
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28 | * \sa MatrixBase::reverse(), VectorwiseOp::reverse()
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29 | */
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30 |
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31 | namespace internal {
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32 |
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33 | template<typename MatrixType, int Direction>
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34 | struct traits<Reverse<MatrixType, Direction> >
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35 | : traits<MatrixType>
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36 | {
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37 | typedef typename MatrixType::Scalar Scalar;
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38 | typedef typename traits<MatrixType>::StorageKind StorageKind;
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39 | typedef typename traits<MatrixType>::XprKind XprKind;
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40 | typedef typename nested<MatrixType>::type MatrixTypeNested;
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41 | typedef typename remove_reference<MatrixTypeNested>::type _MatrixTypeNested;
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42 | enum {
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43 | RowsAtCompileTime = MatrixType::RowsAtCompileTime,
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44 | ColsAtCompileTime = MatrixType::ColsAtCompileTime,
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45 | MaxRowsAtCompileTime = MatrixType::MaxRowsAtCompileTime,
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46 | MaxColsAtCompileTime = MatrixType::MaxColsAtCompileTime,
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47 |
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48 | // let's enable LinearAccess only with vectorization because of the product overhead
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49 | LinearAccess = ( (Direction==BothDirections) && (int(_MatrixTypeNested::Flags)&PacketAccessBit) )
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50 | ? LinearAccessBit : 0,
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51 |
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52 | Flags = int(_MatrixTypeNested::Flags) & (HereditaryBits | LvalueBit | PacketAccessBit | LinearAccess),
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53 |
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54 | CoeffReadCost = _MatrixTypeNested::CoeffReadCost
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55 | };
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56 | };
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57 |
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58 | template<typename PacketScalar, bool ReversePacket> struct reverse_packet_cond
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59 | {
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60 | static inline PacketScalar run(const PacketScalar& x) { return preverse(x); }
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61 | };
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62 |
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63 | template<typename PacketScalar> struct reverse_packet_cond<PacketScalar,false>
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64 | {
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65 | static inline PacketScalar run(const PacketScalar& x) { return x; }
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66 | };
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67 |
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68 | } // end namespace internal
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69 |
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70 | template<typename MatrixType, int Direction> class Reverse
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71 | : public internal::dense_xpr_base< Reverse<MatrixType, Direction> >::type
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72 | {
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73 | public:
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74 |
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75 | typedef typename internal::dense_xpr_base<Reverse>::type Base;
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76 | EIGEN_DENSE_PUBLIC_INTERFACE(Reverse)
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77 | using Base::IsRowMajor;
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78 |
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79 | // next line is necessary because otherwise const version of operator()
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80 | // is hidden by non-const version defined in this file
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81 | using Base::operator();
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82 |
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83 | protected:
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84 | enum {
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85 | PacketSize = internal::packet_traits<Scalar>::size,
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86 | IsColMajor = !IsRowMajor,
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87 | ReverseRow = (Direction == Vertical) || (Direction == BothDirections),
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88 | ReverseCol = (Direction == Horizontal) || (Direction == BothDirections),
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89 | OffsetRow = ReverseRow && IsColMajor ? PacketSize : 1,
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90 | OffsetCol = ReverseCol && IsRowMajor ? PacketSize : 1,
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91 | ReversePacket = (Direction == BothDirections)
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92 | || ((Direction == Vertical) && IsColMajor)
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93 | || ((Direction == Horizontal) && IsRowMajor)
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94 | };
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95 | typedef internal::reverse_packet_cond<PacketScalar,ReversePacket> reverse_packet;
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96 | public:
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97 |
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98 | inline Reverse(const MatrixType& matrix) : m_matrix(matrix) { }
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99 |
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100 | EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Reverse)
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101 |
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102 | inline Index rows() const { return m_matrix.rows(); }
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103 | inline Index cols() const { return m_matrix.cols(); }
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104 |
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105 | inline Index innerStride() const
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106 | {
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107 | return -m_matrix.innerStride();
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108 | }
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109 |
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110 | inline Scalar& operator()(Index row, Index col)
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111 | {
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112 | eigen_assert(row >= 0 && row < rows() && col >= 0 && col < cols());
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113 | return coeffRef(row, col);
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114 | }
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115 |
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116 | inline Scalar& coeffRef(Index row, Index col)
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117 | {
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118 | return m_matrix.const_cast_derived().coeffRef(ReverseRow ? m_matrix.rows() - row - 1 : row,
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119 | ReverseCol ? m_matrix.cols() - col - 1 : col);
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120 | }
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121 |
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122 | inline CoeffReturnType coeff(Index row, Index col) const
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123 | {
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124 | return m_matrix.coeff(ReverseRow ? m_matrix.rows() - row - 1 : row,
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125 | ReverseCol ? m_matrix.cols() - col - 1 : col);
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126 | }
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127 |
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128 | inline CoeffReturnType coeff(Index index) const
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129 | {
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130 | return m_matrix.coeff(m_matrix.size() - index - 1);
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131 | }
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132 |
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133 | inline Scalar& coeffRef(Index index)
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134 | {
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135 | return m_matrix.const_cast_derived().coeffRef(m_matrix.size() - index - 1);
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136 | }
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137 |
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138 | inline Scalar& operator()(Index index)
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139 | {
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140 | eigen_assert(index >= 0 && index < m_matrix.size());
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141 | return coeffRef(index);
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142 | }
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143 |
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144 | template<int LoadMode>
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145 | inline const PacketScalar packet(Index row, Index col) const
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146 | {
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147 | return reverse_packet::run(m_matrix.template packet<LoadMode>(
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148 | ReverseRow ? m_matrix.rows() - row - OffsetRow : row,
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149 | ReverseCol ? m_matrix.cols() - col - OffsetCol : col));
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150 | }
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151 |
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152 | template<int LoadMode>
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153 | inline void writePacket(Index row, Index col, const PacketScalar& x)
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154 | {
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155 | m_matrix.const_cast_derived().template writePacket<LoadMode>(
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156 | ReverseRow ? m_matrix.rows() - row - OffsetRow : row,
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157 | ReverseCol ? m_matrix.cols() - col - OffsetCol : col,
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158 | reverse_packet::run(x));
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159 | }
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160 |
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161 | template<int LoadMode>
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162 | inline const PacketScalar packet(Index index) const
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163 | {
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164 | return internal::preverse(m_matrix.template packet<LoadMode>( m_matrix.size() - index - PacketSize ));
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165 | }
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166 |
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167 | template<int LoadMode>
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168 | inline void writePacket(Index index, const PacketScalar& x)
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169 | {
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170 | m_matrix.const_cast_derived().template writePacket<LoadMode>(m_matrix.size() - index - PacketSize, internal::preverse(x));
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171 | }
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172 |
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173 | const typename internal::remove_all<typename MatrixType::Nested>::type&
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174 | nestedExpression() const
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175 | {
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176 | return m_matrix;
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177 | }
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178 |
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179 | protected:
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180 | typename MatrixType::Nested m_matrix;
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181 | };
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182 |
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183 | /** \returns an expression of the reverse of *this.
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184 | *
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185 | * Example: \include MatrixBase_reverse.cpp
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186 | * Output: \verbinclude MatrixBase_reverse.out
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187 | *
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188 | */
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189 | template<typename Derived>
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190 | inline typename DenseBase<Derived>::ReverseReturnType
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191 | DenseBase<Derived>::reverse()
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192 | {
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193 | return derived();
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194 | }
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195 |
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196 | /** This is the const version of reverse(). */
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197 | template<typename Derived>
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198 | inline const typename DenseBase<Derived>::ConstReverseReturnType
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199 | DenseBase<Derived>::reverse() const
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200 | {
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201 | return derived();
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202 | }
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203 |
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204 | /** This is the "in place" version of reverse: it reverses \c *this.
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205 | *
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206 | * In most cases it is probably better to simply use the reversed expression
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207 | * of a matrix. However, when reversing the matrix data itself is really needed,
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208 | * then this "in-place" version is probably the right choice because it provides
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209 | * the following additional features:
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210 | * - less error prone: doing the same operation with .reverse() requires special care:
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211 | * \code m = m.reverse().eval(); \endcode
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212 | * - this API allows to avoid creating a temporary (the current implementation creates a temporary, but that could be avoided using swap)
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213 | * - it allows future optimizations (cache friendliness, etc.)
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214 | *
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215 | * \sa reverse() */
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216 | template<typename Derived>
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217 | inline void DenseBase<Derived>::reverseInPlace()
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218 | {
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219 | derived() = derived().reverse().eval();
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220 | }
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221 |
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222 | } // end namespace Eigen
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223 |
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224 | #endif // EIGEN_REVERSE_H
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