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) 2007-2010 Benoit Jacob <jacob.benoit.1@gmail.com>
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5 | // Copyright (C) 2008 Gael Guennebaud <gael.guennebaud@inria.fr>
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6 | //
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7 | // This Source Code Form is subject to the terms of the Mozilla
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8 | // Public License v. 2.0. If a copy of the MPL was not distributed
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9 | // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
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10 |
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11 | #ifndef EIGEN_MAP_H
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12 | #define EIGEN_MAP_H
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13 |
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14 | namespace Eigen {
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15 |
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16 | /** \class Map
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17 | * \ingroup Core_Module
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18 | *
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19 | * \brief A matrix or vector expression mapping an existing array of data.
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20 | *
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21 | * \tparam PlainObjectType the equivalent matrix type of the mapped data
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22 | * \tparam MapOptions specifies whether the pointer is \c #Aligned, or \c #Unaligned.
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23 | * The default is \c #Unaligned.
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24 | * \tparam StrideType optionally specifies strides. By default, Map assumes the memory layout
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25 | * of an ordinary, contiguous array. This can be overridden by specifying strides.
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26 | * The type passed here must be a specialization of the Stride template, see examples below.
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27 | *
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28 | * This class represents a matrix or vector expression mapping an existing array of data.
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29 | * It can be used to let Eigen interface without any overhead with non-Eigen data structures,
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30 | * such as plain C arrays or structures from other libraries. By default, it assumes that the
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31 | * data is laid out contiguously in memory. You can however override this by explicitly specifying
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32 | * inner and outer strides.
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33 | *
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34 | * Here's an example of simply mapping a contiguous array as a \ref TopicStorageOrders "column-major" matrix:
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35 | * \include Map_simple.cpp
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36 | * Output: \verbinclude Map_simple.out
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37 | *
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38 | * If you need to map non-contiguous arrays, you can do so by specifying strides:
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39 | *
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40 | * Here's an example of mapping an array as a vector, specifying an inner stride, that is, the pointer
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41 | * increment between two consecutive coefficients. Here, we're specifying the inner stride as a compile-time
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42 | * fixed value.
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43 | * \include Map_inner_stride.cpp
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44 | * Output: \verbinclude Map_inner_stride.out
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45 | *
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46 | * Here's an example of mapping an array while specifying an outer stride. Here, since we're mapping
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47 | * as a column-major matrix, 'outer stride' means the pointer increment between two consecutive columns.
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48 | * Here, we're specifying the outer stride as a runtime parameter. Note that here \c OuterStride<> is
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49 | * a short version of \c OuterStride<Dynamic> because the default template parameter of OuterStride
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50 | * is \c Dynamic
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51 | * \include Map_outer_stride.cpp
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52 | * Output: \verbinclude Map_outer_stride.out
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53 | *
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54 | * For more details and for an example of specifying both an inner and an outer stride, see class Stride.
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55 | *
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56 | * \b Tip: to change the array of data mapped by a Map object, you can use the C++
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57 | * placement new syntax:
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58 | *
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59 | * Example: \include Map_placement_new.cpp
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60 | * Output: \verbinclude Map_placement_new.out
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61 | *
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62 | * This class is the return type of PlainObjectBase::Map() but can also be used directly.
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63 | *
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64 | * \sa PlainObjectBase::Map(), \ref TopicStorageOrders
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65 | */
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66 |
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67 | namespace internal {
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68 | template<typename PlainObjectType, int MapOptions, typename StrideType>
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69 | struct traits<Map<PlainObjectType, MapOptions, StrideType> >
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70 | : public traits<PlainObjectType>
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71 | {
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72 | typedef traits<PlainObjectType> TraitsBase;
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73 | typedef typename PlainObjectType::Index Index;
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74 | typedef typename PlainObjectType::Scalar Scalar;
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75 | enum {
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76 | InnerStrideAtCompileTime = StrideType::InnerStrideAtCompileTime == 0
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77 | ? int(PlainObjectType::InnerStrideAtCompileTime)
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78 | : int(StrideType::InnerStrideAtCompileTime),
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79 | OuterStrideAtCompileTime = StrideType::OuterStrideAtCompileTime == 0
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80 | ? int(PlainObjectType::OuterStrideAtCompileTime)
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81 | : int(StrideType::OuterStrideAtCompileTime),
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82 | HasNoInnerStride = InnerStrideAtCompileTime == 1,
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83 | HasNoOuterStride = StrideType::OuterStrideAtCompileTime == 0,
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84 | HasNoStride = HasNoInnerStride && HasNoOuterStride,
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85 | IsAligned = bool(EIGEN_ALIGN) && ((int(MapOptions)&Aligned)==Aligned),
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86 | IsDynamicSize = PlainObjectType::SizeAtCompileTime==Dynamic,
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87 | KeepsPacketAccess = bool(HasNoInnerStride)
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88 | && ( bool(IsDynamicSize)
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89 | || HasNoOuterStride
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90 | || ( OuterStrideAtCompileTime!=Dynamic
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91 | && ((static_cast<int>(sizeof(Scalar))*OuterStrideAtCompileTime)%16)==0 ) ),
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92 | Flags0 = TraitsBase::Flags & (~NestByRefBit),
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93 | Flags1 = IsAligned ? (int(Flags0) | AlignedBit) : (int(Flags0) & ~AlignedBit),
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94 | Flags2 = (bool(HasNoStride) || bool(PlainObjectType::IsVectorAtCompileTime))
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95 | ? int(Flags1) : int(Flags1 & ~LinearAccessBit),
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96 | Flags3 = is_lvalue<PlainObjectType>::value ? int(Flags2) : (int(Flags2) & ~LvalueBit),
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97 | Flags = KeepsPacketAccess ? int(Flags3) : (int(Flags3) & ~PacketAccessBit)
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98 | };
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99 | private:
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100 | enum { Options }; // Expressions don't have Options
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101 | };
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102 | }
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103 |
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104 | template<typename PlainObjectType, int MapOptions, typename StrideType> class Map
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105 | : public MapBase<Map<PlainObjectType, MapOptions, StrideType> >
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106 | {
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107 | public:
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108 |
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109 | typedef MapBase<Map> Base;
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110 | EIGEN_DENSE_PUBLIC_INTERFACE(Map)
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111 |
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112 | typedef typename Base::PointerType PointerType;
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113 | #if EIGEN2_SUPPORT_STAGE <= STAGE30_FULL_EIGEN3_API
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114 | typedef const Scalar* PointerArgType;
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115 | inline PointerType cast_to_pointer_type(PointerArgType ptr) { return const_cast<PointerType>(ptr); }
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116 | #else
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117 | typedef PointerType PointerArgType;
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118 | inline PointerType cast_to_pointer_type(PointerArgType ptr) { return ptr; }
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119 | #endif
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120 |
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121 | inline Index innerStride() const
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122 | {
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123 | return StrideType::InnerStrideAtCompileTime != 0 ? m_stride.inner() : 1;
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124 | }
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125 |
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126 | inline Index outerStride() const
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127 | {
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128 | return StrideType::OuterStrideAtCompileTime != 0 ? m_stride.outer()
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129 | : IsVectorAtCompileTime ? this->size()
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130 | : int(Flags)&RowMajorBit ? this->cols()
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131 | : this->rows();
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132 | }
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133 |
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134 | /** Constructor in the fixed-size case.
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135 | *
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136 | * \param dataPtr pointer to the array to map
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137 | * \param a_stride optional Stride object, passing the strides.
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138 | */
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139 | inline Map(PointerArgType dataPtr, const StrideType& a_stride = StrideType())
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140 | : Base(cast_to_pointer_type(dataPtr)), m_stride(a_stride)
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141 | {
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142 | PlainObjectType::Base::_check_template_params();
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143 | }
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144 |
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145 | /** Constructor in the dynamic-size vector case.
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146 | *
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147 | * \param dataPtr pointer to the array to map
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148 | * \param a_size the size of the vector expression
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149 | * \param a_stride optional Stride object, passing the strides.
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150 | */
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151 | inline Map(PointerArgType dataPtr, Index a_size, const StrideType& a_stride = StrideType())
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152 | : Base(cast_to_pointer_type(dataPtr), a_size), m_stride(a_stride)
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153 | {
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154 | PlainObjectType::Base::_check_template_params();
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155 | }
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156 |
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157 | /** Constructor in the dynamic-size matrix case.
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158 | *
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159 | * \param dataPtr pointer to the array to map
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160 | * \param nbRows the number of rows of the matrix expression
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161 | * \param nbCols the number of columns of the matrix expression
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162 | * \param a_stride optional Stride object, passing the strides.
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163 | */
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164 | inline Map(PointerArgType dataPtr, Index nbRows, Index nbCols, const StrideType& a_stride = StrideType())
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165 | : Base(cast_to_pointer_type(dataPtr), nbRows, nbCols), m_stride(a_stride)
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166 | {
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167 | PlainObjectType::Base::_check_template_params();
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168 | }
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169 |
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170 | EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Map)
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171 |
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172 | protected:
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173 | StrideType m_stride;
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174 | };
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175 |
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176 | template<typename _Scalar, int _Rows, int _Cols, int _Options, int _MaxRows, int _MaxCols>
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177 | inline Array<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>
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178 | ::Array(const Scalar *data)
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179 | {
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180 | this->_set_noalias(Eigen::Map<const Array>(data));
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181 | }
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182 |
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183 | template<typename _Scalar, int _Rows, int _Cols, int _Options, int _MaxRows, int _MaxCols>
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184 | inline Matrix<_Scalar, _Rows, _Cols, _Options, _MaxRows, _MaxCols>
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185 | ::Matrix(const Scalar *data)
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186 | {
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187 | this->_set_noalias(Eigen::Map<const Matrix>(data));
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188 | }
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189 |
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190 | } // end namespace Eigen
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191 |
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192 | #endif // EIGEN_MAP_H
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