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      1 // This file is part of Eigen, a lightweight C++ template library
      2 // for linear algebra.
      3 //
      4 // Copyright (C) 2009-2010 Gael Guennebaud <gael.guennebaud (at) inria.fr>
      5 //
      6 // This Source Code Form is subject to the terms of the Mozilla
      7 // Public License v. 2.0. If a copy of the MPL was not distributed
      8 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
      9 
     10 #ifndef EIGEN_PRODUCTBASE_H
     11 #define EIGEN_PRODUCTBASE_H
     12 
     13 namespace Eigen {
     14 
     15 /** \class ProductBase
     16   * \ingroup Core_Module
     17   *
     18   */
     19 
     20 namespace internal {
     21 template<typename Derived, typename _Lhs, typename _Rhs>
     22 struct traits<ProductBase<Derived,_Lhs,_Rhs> >
     23 {
     24   typedef MatrixXpr XprKind;
     25   typedef typename remove_all<_Lhs>::type Lhs;
     26   typedef typename remove_all<_Rhs>::type Rhs;
     27   typedef typename scalar_product_traits<typename Lhs::Scalar, typename Rhs::Scalar>::ReturnType Scalar;
     28   typedef typename promote_storage_type<typename traits<Lhs>::StorageKind,
     29                                            typename traits<Rhs>::StorageKind>::ret StorageKind;
     30   typedef typename promote_index_type<typename traits<Lhs>::Index,
     31                                          typename traits<Rhs>::Index>::type Index;
     32   enum {
     33     RowsAtCompileTime = traits<Lhs>::RowsAtCompileTime,
     34     ColsAtCompileTime = traits<Rhs>::ColsAtCompileTime,
     35     MaxRowsAtCompileTime = traits<Lhs>::MaxRowsAtCompileTime,
     36     MaxColsAtCompileTime = traits<Rhs>::MaxColsAtCompileTime,
     37     Flags = (MaxRowsAtCompileTime==1 ? RowMajorBit : 0)
     38           | EvalBeforeNestingBit | EvalBeforeAssigningBit | NestByRefBit,
     39                   // Note that EvalBeforeNestingBit and NestByRefBit
     40                   // are not used in practice because nested is overloaded for products
     41     CoeffReadCost = 0 // FIXME why is it needed ?
     42   };
     43 };
     44 }
     45 
     46 #define EIGEN_PRODUCT_PUBLIC_INTERFACE(Derived) \
     47   typedef ProductBase<Derived, Lhs, Rhs > Base; \
     48   EIGEN_DENSE_PUBLIC_INTERFACE(Derived) \
     49   typedef typename Base::LhsNested LhsNested; \
     50   typedef typename Base::_LhsNested _LhsNested; \
     51   typedef typename Base::LhsBlasTraits LhsBlasTraits; \
     52   typedef typename Base::ActualLhsType ActualLhsType; \
     53   typedef typename Base::_ActualLhsType _ActualLhsType; \
     54   typedef typename Base::RhsNested RhsNested; \
     55   typedef typename Base::_RhsNested _RhsNested; \
     56   typedef typename Base::RhsBlasTraits RhsBlasTraits; \
     57   typedef typename Base::ActualRhsType ActualRhsType; \
     58   typedef typename Base::_ActualRhsType _ActualRhsType; \
     59   using Base::m_lhs; \
     60   using Base::m_rhs;
     61 
     62 template<typename Derived, typename Lhs, typename Rhs>
     63 class ProductBase : public MatrixBase<Derived>
     64 {
     65   public:
     66     typedef MatrixBase<Derived> Base;
     67     EIGEN_DENSE_PUBLIC_INTERFACE(ProductBase)
     68 
     69     typedef typename Lhs::Nested LhsNested;
     70     typedef typename internal::remove_all<LhsNested>::type _LhsNested;
     71     typedef internal::blas_traits<_LhsNested> LhsBlasTraits;
     72     typedef typename LhsBlasTraits::DirectLinearAccessType ActualLhsType;
     73     typedef typename internal::remove_all<ActualLhsType>::type _ActualLhsType;
     74     typedef typename internal::traits<Lhs>::Scalar LhsScalar;
     75 
     76     typedef typename Rhs::Nested RhsNested;
     77     typedef typename internal::remove_all<RhsNested>::type _RhsNested;
     78     typedef internal::blas_traits<_RhsNested> RhsBlasTraits;
     79     typedef typename RhsBlasTraits::DirectLinearAccessType ActualRhsType;
     80     typedef typename internal::remove_all<ActualRhsType>::type _ActualRhsType;
     81     typedef typename internal::traits<Rhs>::Scalar RhsScalar;
     82 
     83     // Diagonal of a product: no need to evaluate the arguments because they are going to be evaluated only once
     84     typedef CoeffBasedProduct<LhsNested, RhsNested, 0> FullyLazyCoeffBaseProductType;
     85 
     86   public:
     87 
     88     typedef typename Base::PlainObject PlainObject;
     89 
     90     ProductBase(const Lhs& lhs, const Rhs& rhs)
     91       : m_lhs(lhs), m_rhs(rhs)
     92     {
     93       eigen_assert(lhs.cols() == rhs.rows()
     94         && "invalid matrix product"
     95         && "if you wanted a coeff-wise or a dot product use the respective explicit functions");
     96     }
     97 
     98     inline Index rows() const { return m_lhs.rows(); }
     99     inline Index cols() const { return m_rhs.cols(); }
    100 
    101     template<typename Dest>
    102     inline void evalTo(Dest& dst) const { dst.setZero(); scaleAndAddTo(dst,Scalar(1)); }
    103 
    104     template<typename Dest>
    105     inline void addTo(Dest& dst) const { scaleAndAddTo(dst,Scalar(1)); }
    106 
    107     template<typename Dest>
    108     inline void subTo(Dest& dst) const { scaleAndAddTo(dst,Scalar(-1)); }
    109 
    110     template<typename Dest>
    111     inline void scaleAndAddTo(Dest& dst,Scalar alpha) const { derived().scaleAndAddTo(dst,alpha); }
    112 
    113     const _LhsNested& lhs() const { return m_lhs; }
    114     const _RhsNested& rhs() const { return m_rhs; }
    115 
    116     // Implicit conversion to the nested type (trigger the evaluation of the product)
    117     operator const PlainObject& () const
    118     {
    119       m_result.resize(m_lhs.rows(), m_rhs.cols());
    120       derived().evalTo(m_result);
    121       return m_result;
    122     }
    123 
    124     const Diagonal<const FullyLazyCoeffBaseProductType,0> diagonal() const
    125     { return FullyLazyCoeffBaseProductType(m_lhs, m_rhs); }
    126 
    127     template<int Index>
    128     const Diagonal<FullyLazyCoeffBaseProductType,Index> diagonal() const
    129     { return FullyLazyCoeffBaseProductType(m_lhs, m_rhs); }
    130 
    131     const Diagonal<FullyLazyCoeffBaseProductType,Dynamic> diagonal(Index index) const
    132     { return FullyLazyCoeffBaseProductType(m_lhs, m_rhs).diagonal(index); }
    133 
    134     // restrict coeff accessors to 1x1 expressions. No need to care about mutators here since this isnt a Lvalue expression
    135     typename Base::CoeffReturnType coeff(Index row, Index col) const
    136     {
    137 #ifdef EIGEN2_SUPPORT
    138       return lhs().row(row).cwiseProduct(rhs().col(col).transpose()).sum();
    139 #else
    140       EIGEN_STATIC_ASSERT_SIZE_1x1(Derived)
    141       eigen_assert(this->rows() == 1 && this->cols() == 1);
    142       Matrix<Scalar,1,1> result = *this;
    143       return result.coeff(row,col);
    144 #endif
    145     }
    146 
    147     typename Base::CoeffReturnType coeff(Index i) const
    148     {
    149       EIGEN_STATIC_ASSERT_SIZE_1x1(Derived)
    150       eigen_assert(this->rows() == 1 && this->cols() == 1);
    151       Matrix<Scalar,1,1> result = *this;
    152       return result.coeff(i);
    153     }
    154 
    155     const Scalar& coeffRef(Index row, Index col) const
    156     {
    157       EIGEN_STATIC_ASSERT_SIZE_1x1(Derived)
    158       eigen_assert(this->rows() == 1 && this->cols() == 1);
    159       return derived().coeffRef(row,col);
    160     }
    161 
    162     const Scalar& coeffRef(Index i) const
    163     {
    164       EIGEN_STATIC_ASSERT_SIZE_1x1(Derived)
    165       eigen_assert(this->rows() == 1 && this->cols() == 1);
    166       return derived().coeffRef(i);
    167     }
    168 
    169   protected:
    170 
    171     LhsNested m_lhs;
    172     RhsNested m_rhs;
    173 
    174     mutable PlainObject m_result;
    175 };
    176 
    177 // here we need to overload the nested rule for products
    178 // such that the nested type is a const reference to a plain matrix
    179 namespace internal {
    180 template<typename Lhs, typename Rhs, int Mode, int N, typename PlainObject>
    181 struct nested<GeneralProduct<Lhs,Rhs,Mode>, N, PlainObject>
    182 {
    183   typedef PlainObject const& type;
    184 };
    185 }
    186 
    187 template<typename NestedProduct>
    188 class ScaledProduct;
    189 
    190 // Note that these two operator* functions are not defined as member
    191 // functions of ProductBase, because, otherwise we would have to
    192 // define all overloads defined in MatrixBase. Furthermore, Using
    193 // "using Base::operator*" would not work with MSVC.
    194 //
    195 // Also note that here we accept any compatible scalar types
    196 template<typename Derived,typename Lhs,typename Rhs>
    197 const ScaledProduct<Derived>
    198 operator*(const ProductBase<Derived,Lhs,Rhs>& prod, typename Derived::Scalar x)
    199 { return ScaledProduct<Derived>(prod.derived(), x); }
    200 
    201 template<typename Derived,typename Lhs,typename Rhs>
    202 typename internal::enable_if<!internal::is_same<typename Derived::Scalar,typename Derived::RealScalar>::value,
    203                       const ScaledProduct<Derived> >::type
    204 operator*(const ProductBase<Derived,Lhs,Rhs>& prod, typename Derived::RealScalar x)
    205 { return ScaledProduct<Derived>(prod.derived(), x); }
    206 
    207 
    208 template<typename Derived,typename Lhs,typename Rhs>
    209 const ScaledProduct<Derived>
    210 operator*(typename Derived::Scalar x,const ProductBase<Derived,Lhs,Rhs>& prod)
    211 { return ScaledProduct<Derived>(prod.derived(), x); }
    212 
    213 template<typename Derived,typename Lhs,typename Rhs>
    214 typename internal::enable_if<!internal::is_same<typename Derived::Scalar,typename Derived::RealScalar>::value,
    215                       const ScaledProduct<Derived> >::type
    216 operator*(typename Derived::RealScalar x,const ProductBase<Derived,Lhs,Rhs>& prod)
    217 { return ScaledProduct<Derived>(prod.derived(), x); }
    218 
    219 namespace internal {
    220 template<typename NestedProduct>
    221 struct traits<ScaledProduct<NestedProduct> >
    222  : traits<ProductBase<ScaledProduct<NestedProduct>,
    223                          typename NestedProduct::_LhsNested,
    224                          typename NestedProduct::_RhsNested> >
    225 {
    226   typedef typename traits<NestedProduct>::StorageKind StorageKind;
    227 };
    228 }
    229 
    230 template<typename NestedProduct>
    231 class ScaledProduct
    232   : public ProductBase<ScaledProduct<NestedProduct>,
    233                        typename NestedProduct::_LhsNested,
    234                        typename NestedProduct::_RhsNested>
    235 {
    236   public:
    237     typedef ProductBase<ScaledProduct<NestedProduct>,
    238                        typename NestedProduct::_LhsNested,
    239                        typename NestedProduct::_RhsNested> Base;
    240     typedef typename Base::Scalar Scalar;
    241     typedef typename Base::PlainObject PlainObject;
    242 //     EIGEN_PRODUCT_PUBLIC_INTERFACE(ScaledProduct)
    243 
    244     ScaledProduct(const NestedProduct& prod, Scalar x)
    245     : Base(prod.lhs(),prod.rhs()), m_prod(prod), m_alpha(x) {}
    246 
    247     template<typename Dest>
    248     inline void evalTo(Dest& dst) const { dst.setZero(); scaleAndAddTo(dst, Scalar(1)); }
    249 
    250     template<typename Dest>
    251     inline void addTo(Dest& dst) const { scaleAndAddTo(dst, Scalar(1)); }
    252 
    253     template<typename Dest>
    254     inline void subTo(Dest& dst) const { scaleAndAddTo(dst, Scalar(-1)); }
    255 
    256     template<typename Dest>
    257     inline void scaleAndAddTo(Dest& dst,Scalar alpha) const { m_prod.derived().scaleAndAddTo(dst,alpha * m_alpha); }
    258 
    259     const Scalar& alpha() const { return m_alpha; }
    260 
    261   protected:
    262     const NestedProduct& m_prod;
    263     Scalar m_alpha;
    264 };
    265 
    266 /** \internal
    267   * Overloaded to perform an efficient C = (A*B).lazy() */
    268 template<typename Derived>
    269 template<typename ProductDerived, typename Lhs, typename Rhs>
    270 Derived& MatrixBase<Derived>::lazyAssign(const ProductBase<ProductDerived, Lhs,Rhs>& other)
    271 {
    272   other.derived().evalTo(derived());
    273   return derived();
    274 }
    275 
    276 } // end namespace Eigen
    277 
    278 #endif // EIGEN_PRODUCTBASE_H
    279