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      1 // This file is part of Eigen, a lightweight C++ template library
      2 // for linear algebra.
      3 //
      4 // Copyright (C) 2006-2008 Benoit Jacob <jacob.benoit.1 (at) gmail.com>
      5 // Copyright (C) 2009-2010 Gael Guennebaud <gael.guennebaud (at) inria.fr>
      6 //
      7 // This Source Code Form is subject to the terms of the Mozilla
      8 // Public License v. 2.0. If a copy of the MPL was not distributed
      9 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
     10 
     11 #ifndef EIGEN_TRANSPOSE_H
     12 #define EIGEN_TRANSPOSE_H
     13 
     14 namespace Eigen {
     15 
     16 /** \class Transpose
     17   * \ingroup Core_Module
     18   *
     19   * \brief Expression of the transpose of a matrix
     20   *
     21   * \param MatrixType the type of the object of which we are taking the transpose
     22   *
     23   * This class represents an expression of the transpose of a matrix.
     24   * It is the return type of MatrixBase::transpose() and MatrixBase::adjoint()
     25   * and most of the time this is the only way it is used.
     26   *
     27   * \sa MatrixBase::transpose(), MatrixBase::adjoint()
     28   */
     29 
     30 namespace internal {
     31 template<typename MatrixType>
     32 struct traits<Transpose<MatrixType> > : traits<MatrixType>
     33 {
     34   typedef typename MatrixType::Scalar Scalar;
     35   typedef typename nested<MatrixType>::type MatrixTypeNested;
     36   typedef typename remove_reference<MatrixTypeNested>::type MatrixTypeNestedPlain;
     37   typedef typename traits<MatrixType>::StorageKind StorageKind;
     38   typedef typename traits<MatrixType>::XprKind XprKind;
     39   enum {
     40     RowsAtCompileTime = MatrixType::ColsAtCompileTime,
     41     ColsAtCompileTime = MatrixType::RowsAtCompileTime,
     42     MaxRowsAtCompileTime = MatrixType::MaxColsAtCompileTime,
     43     MaxColsAtCompileTime = MatrixType::MaxRowsAtCompileTime,
     44     FlagsLvalueBit = is_lvalue<MatrixType>::value ? LvalueBit : 0,
     45     Flags0 = MatrixTypeNestedPlain::Flags & ~(LvalueBit | NestByRefBit),
     46     Flags1 = Flags0 | FlagsLvalueBit,
     47     Flags = Flags1 ^ RowMajorBit,
     48     CoeffReadCost = MatrixTypeNestedPlain::CoeffReadCost,
     49     InnerStrideAtCompileTime = inner_stride_at_compile_time<MatrixType>::ret,
     50     OuterStrideAtCompileTime = outer_stride_at_compile_time<MatrixType>::ret
     51   };
     52 };
     53 }
     54 
     55 template<typename MatrixType, typename StorageKind> class TransposeImpl;
     56 
     57 template<typename MatrixType> class Transpose
     58   : public TransposeImpl<MatrixType,typename internal::traits<MatrixType>::StorageKind>
     59 {
     60   public:
     61 
     62     typedef typename TransposeImpl<MatrixType,typename internal::traits<MatrixType>::StorageKind>::Base Base;
     63     EIGEN_GENERIC_PUBLIC_INTERFACE(Transpose)
     64 
     65     inline Transpose(MatrixType& a_matrix) : m_matrix(a_matrix) {}
     66 
     67     EIGEN_INHERIT_ASSIGNMENT_OPERATORS(Transpose)
     68 
     69     inline Index rows() const { return m_matrix.cols(); }
     70     inline Index cols() const { return m_matrix.rows(); }
     71 
     72     /** \returns the nested expression */
     73     const typename internal::remove_all<typename MatrixType::Nested>::type&
     74     nestedExpression() const { return m_matrix; }
     75 
     76     /** \returns the nested expression */
     77     typename internal::remove_all<typename MatrixType::Nested>::type&
     78     nestedExpression() { return m_matrix.const_cast_derived(); }
     79 
     80   protected:
     81     typename MatrixType::Nested m_matrix;
     82 };
     83 
     84 namespace internal {
     85 
     86 template<typename MatrixType, bool HasDirectAccess = has_direct_access<MatrixType>::ret>
     87 struct TransposeImpl_base
     88 {
     89   typedef typename dense_xpr_base<Transpose<MatrixType> >::type type;
     90 };
     91 
     92 template<typename MatrixType>
     93 struct TransposeImpl_base<MatrixType, false>
     94 {
     95   typedef typename dense_xpr_base<Transpose<MatrixType> >::type type;
     96 };
     97 
     98 } // end namespace internal
     99 
    100 template<typename MatrixType> class TransposeImpl<MatrixType,Dense>
    101   : public internal::TransposeImpl_base<MatrixType>::type
    102 {
    103   public:
    104 
    105     typedef typename internal::TransposeImpl_base<MatrixType>::type Base;
    106     EIGEN_DENSE_PUBLIC_INTERFACE(Transpose<MatrixType>)
    107     EIGEN_INHERIT_ASSIGNMENT_OPERATORS(TransposeImpl)
    108 
    109     inline Index innerStride() const { return derived().nestedExpression().innerStride(); }
    110     inline Index outerStride() const { return derived().nestedExpression().outerStride(); }
    111 
    112     typedef typename internal::conditional<
    113                        internal::is_lvalue<MatrixType>::value,
    114                        Scalar,
    115                        const Scalar
    116                      >::type ScalarWithConstIfNotLvalue;
    117 
    118     inline ScalarWithConstIfNotLvalue* data() { return derived().nestedExpression().data(); }
    119     inline const Scalar* data() const { return derived().nestedExpression().data(); }
    120 
    121     inline ScalarWithConstIfNotLvalue& coeffRef(Index rowId, Index colId)
    122     {
    123       EIGEN_STATIC_ASSERT_LVALUE(MatrixType)
    124       return derived().nestedExpression().const_cast_derived().coeffRef(colId, rowId);
    125     }
    126 
    127     inline ScalarWithConstIfNotLvalue& coeffRef(Index index)
    128     {
    129       EIGEN_STATIC_ASSERT_LVALUE(MatrixType)
    130       return derived().nestedExpression().const_cast_derived().coeffRef(index);
    131     }
    132 
    133     inline const Scalar& coeffRef(Index rowId, Index colId) const
    134     {
    135       return derived().nestedExpression().coeffRef(colId, rowId);
    136     }
    137 
    138     inline const Scalar& coeffRef(Index index) const
    139     {
    140       return derived().nestedExpression().coeffRef(index);
    141     }
    142 
    143     inline CoeffReturnType coeff(Index rowId, Index colId) const
    144     {
    145       return derived().nestedExpression().coeff(colId, rowId);
    146     }
    147 
    148     inline CoeffReturnType coeff(Index index) const
    149     {
    150       return derived().nestedExpression().coeff(index);
    151     }
    152 
    153     template<int LoadMode>
    154     inline const PacketScalar packet(Index rowId, Index colId) const
    155     {
    156       return derived().nestedExpression().template packet<LoadMode>(colId, rowId);
    157     }
    158 
    159     template<int LoadMode>
    160     inline void writePacket(Index rowId, Index colId, const PacketScalar& x)
    161     {
    162       derived().nestedExpression().const_cast_derived().template writePacket<LoadMode>(colId, rowId, x);
    163     }
    164 
    165     template<int LoadMode>
    166     inline const PacketScalar packet(Index index) const
    167     {
    168       return derived().nestedExpression().template packet<LoadMode>(index);
    169     }
    170 
    171     template<int LoadMode>
    172     inline void writePacket(Index index, const PacketScalar& x)
    173     {
    174       derived().nestedExpression().const_cast_derived().template writePacket<LoadMode>(index, x);
    175     }
    176 };
    177 
    178 /** \returns an expression of the transpose of *this.
    179   *
    180   * Example: \include MatrixBase_transpose.cpp
    181   * Output: \verbinclude MatrixBase_transpose.out
    182   *
    183   * \warning If you want to replace a matrix by its own transpose, do \b NOT do this:
    184   * \code
    185   * m = m.transpose(); // bug!!! caused by aliasing effect
    186   * \endcode
    187   * Instead, use the transposeInPlace() method:
    188   * \code
    189   * m.transposeInPlace();
    190   * \endcode
    191   * which gives Eigen good opportunities for optimization, or alternatively you can also do:
    192   * \code
    193   * m = m.transpose().eval();
    194   * \endcode
    195   *
    196   * \sa transposeInPlace(), adjoint() */
    197 template<typename Derived>
    198 inline Transpose<Derived>
    199 DenseBase<Derived>::transpose()
    200 {
    201   return derived();
    202 }
    203 
    204 /** This is the const version of transpose().
    205   *
    206   * Make sure you read the warning for transpose() !
    207   *
    208   * \sa transposeInPlace(), adjoint() */
    209 template<typename Derived>
    210 inline typename DenseBase<Derived>::ConstTransposeReturnType
    211 DenseBase<Derived>::transpose() const
    212 {
    213   return ConstTransposeReturnType(derived());
    214 }
    215 
    216 /** \returns an expression of the adjoint (i.e. conjugate transpose) of *this.
    217   *
    218   * Example: \include MatrixBase_adjoint.cpp
    219   * Output: \verbinclude MatrixBase_adjoint.out
    220   *
    221   * \warning If you want to replace a matrix by its own adjoint, do \b NOT do this:
    222   * \code
    223   * m = m.adjoint(); // bug!!! caused by aliasing effect
    224   * \endcode
    225   * Instead, use the adjointInPlace() method:
    226   * \code
    227   * m.adjointInPlace();
    228   * \endcode
    229   * which gives Eigen good opportunities for optimization, or alternatively you can also do:
    230   * \code
    231   * m = m.adjoint().eval();
    232   * \endcode
    233   *
    234   * \sa adjointInPlace(), transpose(), conjugate(), class Transpose, class internal::scalar_conjugate_op */
    235 template<typename Derived>
    236 inline const typename MatrixBase<Derived>::AdjointReturnType
    237 MatrixBase<Derived>::adjoint() const
    238 {
    239   return this->transpose(); // in the complex case, the .conjugate() is be implicit here
    240                             // due to implicit conversion to return type
    241 }
    242 
    243 /***************************************************************************
    244 * "in place" transpose implementation
    245 ***************************************************************************/
    246 
    247 namespace internal {
    248 
    249 template<typename MatrixType,
    250   bool IsSquare = (MatrixType::RowsAtCompileTime == MatrixType::ColsAtCompileTime) && MatrixType::RowsAtCompileTime!=Dynamic>
    251 struct inplace_transpose_selector;
    252 
    253 template<typename MatrixType>
    254 struct inplace_transpose_selector<MatrixType,true> { // square matrix
    255   static void run(MatrixType& m) {
    256     m.matrix().template triangularView<StrictlyUpper>().swap(m.matrix().transpose());
    257   }
    258 };
    259 
    260 template<typename MatrixType>
    261 struct inplace_transpose_selector<MatrixType,false> { // non square matrix
    262   static void run(MatrixType& m) {
    263     if (m.rows()==m.cols())
    264       m.matrix().template triangularView<StrictlyUpper>().swap(m.matrix().transpose());
    265     else
    266       m = m.transpose().eval();
    267   }
    268 };
    269 
    270 } // end namespace internal
    271 
    272 /** This is the "in place" version of transpose(): it replaces \c *this by its own transpose.
    273   * Thus, doing
    274   * \code
    275   * m.transposeInPlace();
    276   * \endcode
    277   * has the same effect on m as doing
    278   * \code
    279   * m = m.transpose().eval();
    280   * \endcode
    281   * and is faster and also safer because in the latter line of code, forgetting the eval() results
    282   * in a bug caused by \ref TopicAliasing "aliasing".
    283   *
    284   * Notice however that this method is only useful if you want to replace a matrix by its own transpose.
    285   * If you just need the transpose of a matrix, use transpose().
    286   *
    287   * \note if the matrix is not square, then \c *this must be a resizable matrix.
    288   * This excludes (non-square) fixed-size matrices, block-expressions and maps.
    289   *
    290   * \sa transpose(), adjoint(), adjointInPlace() */
    291 template<typename Derived>
    292 inline void DenseBase<Derived>::transposeInPlace()
    293 {
    294   eigen_assert((rows() == cols() || (RowsAtCompileTime == Dynamic && ColsAtCompileTime == Dynamic))
    295                && "transposeInPlace() called on a non-square non-resizable matrix");
    296   internal::inplace_transpose_selector<Derived>::run(derived());
    297 }
    298 
    299 /***************************************************************************
    300 * "in place" adjoint implementation
    301 ***************************************************************************/
    302 
    303 /** This is the "in place" version of adjoint(): it replaces \c *this by its own transpose.
    304   * Thus, doing
    305   * \code
    306   * m.adjointInPlace();
    307   * \endcode
    308   * has the same effect on m as doing
    309   * \code
    310   * m = m.adjoint().eval();
    311   * \endcode
    312   * and is faster and also safer because in the latter line of code, forgetting the eval() results
    313   * in a bug caused by aliasing.
    314   *
    315   * Notice however that this method is only useful if you want to replace a matrix by its own adjoint.
    316   * If you just need the adjoint of a matrix, use adjoint().
    317   *
    318   * \note if the matrix is not square, then \c *this must be a resizable matrix.
    319   * This excludes (non-square) fixed-size matrices, block-expressions and maps.
    320   *
    321   * \sa transpose(), adjoint(), transposeInPlace() */
    322 template<typename Derived>
    323 inline void MatrixBase<Derived>::adjointInPlace()
    324 {
    325   derived() = adjoint().eval();
    326 }
    327 
    328 #ifndef EIGEN_NO_DEBUG
    329 
    330 // The following is to detect aliasing problems in most common cases.
    331 
    332 namespace internal {
    333 
    334 template<typename BinOp,typename NestedXpr,typename Rhs>
    335 struct blas_traits<SelfCwiseBinaryOp<BinOp,NestedXpr,Rhs> >
    336  : blas_traits<NestedXpr>
    337 {
    338   typedef SelfCwiseBinaryOp<BinOp,NestedXpr,Rhs> XprType;
    339   static inline const XprType extract(const XprType& x) { return x; }
    340 };
    341 
    342 template<bool DestIsTransposed, typename OtherDerived>
    343 struct check_transpose_aliasing_compile_time_selector
    344 {
    345   enum { ret = bool(blas_traits<OtherDerived>::IsTransposed) != DestIsTransposed };
    346 };
    347 
    348 template<bool DestIsTransposed, typename BinOp, typename DerivedA, typename DerivedB>
    349 struct check_transpose_aliasing_compile_time_selector<DestIsTransposed,CwiseBinaryOp<BinOp,DerivedA,DerivedB> >
    350 {
    351   enum { ret =    bool(blas_traits<DerivedA>::IsTransposed) != DestIsTransposed
    352                || bool(blas_traits<DerivedB>::IsTransposed) != DestIsTransposed
    353   };
    354 };
    355 
    356 template<typename Scalar, bool DestIsTransposed, typename OtherDerived>
    357 struct check_transpose_aliasing_run_time_selector
    358 {
    359   static bool run(const Scalar* dest, const OtherDerived& src)
    360   {
    361     return (bool(blas_traits<OtherDerived>::IsTransposed) != DestIsTransposed) && (dest!=0 && dest==(const Scalar*)extract_data(src));
    362   }
    363 };
    364 
    365 template<typename Scalar, bool DestIsTransposed, typename BinOp, typename DerivedA, typename DerivedB>
    366 struct check_transpose_aliasing_run_time_selector<Scalar,DestIsTransposed,CwiseBinaryOp<BinOp,DerivedA,DerivedB> >
    367 {
    368   static bool run(const Scalar* dest, const CwiseBinaryOp<BinOp,DerivedA,DerivedB>& src)
    369   {
    370     return ((blas_traits<DerivedA>::IsTransposed != DestIsTransposed) && (dest!=0 && dest==(const Scalar*)extract_data(src.lhs())))
    371         || ((blas_traits<DerivedB>::IsTransposed != DestIsTransposed) && (dest!=0 && dest==(const Scalar*)extract_data(src.rhs())));
    372   }
    373 };
    374 
    375 // the following selector, checkTransposeAliasing_impl, based on MightHaveTransposeAliasing,
    376 // is because when the condition controlling the assert is known at compile time, ICC emits a warning.
    377 // This is actually a good warning: in expressions that don't have any transposing, the condition is
    378 // known at compile time to be false, and using that, we can avoid generating the code of the assert again
    379 // and again for all these expressions that don't need it.
    380 
    381 template<typename Derived, typename OtherDerived,
    382          bool MightHaveTransposeAliasing
    383                  = check_transpose_aliasing_compile_time_selector
    384                      <blas_traits<Derived>::IsTransposed,OtherDerived>::ret
    385         >
    386 struct checkTransposeAliasing_impl
    387 {
    388     static void run(const Derived& dst, const OtherDerived& other)
    389     {
    390         eigen_assert((!check_transpose_aliasing_run_time_selector
    391                       <typename Derived::Scalar,blas_traits<Derived>::IsTransposed,OtherDerived>
    392                       ::run(extract_data(dst), other))
    393           && "aliasing detected during transposition, use transposeInPlace() "
    394              "or evaluate the rhs into a temporary using .eval()");
    395 
    396     }
    397 };
    398 
    399 template<typename Derived, typename OtherDerived>
    400 struct checkTransposeAliasing_impl<Derived, OtherDerived, false>
    401 {
    402     static void run(const Derived&, const OtherDerived&)
    403     {
    404     }
    405 };
    406 
    407 } // end namespace internal
    408 
    409 template<typename Derived>
    410 template<typename OtherDerived>
    411 void DenseBase<Derived>::checkTransposeAliasing(const OtherDerived& other) const
    412 {
    413     internal::checkTransposeAliasing_impl<Derived, OtherDerived>::run(derived(), other);
    414 }
    415 #endif
    416 
    417 } // end namespace Eigen
    418 
    419 #endif // EIGEN_TRANSPOSE_H
    420