Diff: src/Core/TriangularMatrix.h

Revision:

0:13a5d365ba16

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/Core/TriangularMatrix.h	Thu Oct 13 04:07:23 2016 +0000
@@ -0,0 +1,839 @@
+// This file is part of Eigen, a lightweight C++ template library
+// for linear algebra.
+//
+// Copyright (C) 2008 Benoit Jacob <jacob.benoit.1@gmail.com>
+// Copyright (C) 2008-2009 Gael Guennebaud <gael.guennebaud@inria.fr>
+//
+// 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_TRIANGULARMATRIX_H
+#define EIGEN_TRIANGULARMATRIX_H
+
+namespace Eigen { 
+
+namespace internal {
+  
+template<int Side, typename TriangularType, typename Rhs> struct triangular_solve_retval;
+  
+}
+
+/** \internal
+  *
+  * \class TriangularBase
+  * \ingroup Core_Module
+  *
+  * \brief Base class for triangular part in a matrix
+  */
+template<typename Derived> class TriangularBase : public EigenBase<Derived>
+{
+  public:
+
+    enum {
+      Mode = internal::traits<Derived>::Mode,
+      CoeffReadCost = internal::traits<Derived>::CoeffReadCost,
+      RowsAtCompileTime = internal::traits<Derived>::RowsAtCompileTime,
+      ColsAtCompileTime = internal::traits<Derived>::ColsAtCompileTime,
+      MaxRowsAtCompileTime = internal::traits<Derived>::MaxRowsAtCompileTime,
+      MaxColsAtCompileTime = internal::traits<Derived>::MaxColsAtCompileTime
+    };
+    typedef typename internal::traits<Derived>::Scalar Scalar;
+    typedef typename internal::traits<Derived>::StorageKind StorageKind;
+    typedef typename internal::traits<Derived>::Index Index;
+    typedef typename internal::traits<Derived>::DenseMatrixType DenseMatrixType;
+    typedef DenseMatrixType DenseType;
+
+    inline TriangularBase() { eigen_assert(!((Mode&UnitDiag) && (Mode&ZeroDiag))); }
+
+    inline Index rows() const { return derived().rows(); }
+    inline Index cols() const { return derived().cols(); }
+    inline Index outerStride() const { return derived().outerStride(); }
+    inline Index innerStride() const { return derived().innerStride(); }
+
+    inline Scalar coeff(Index row, Index col) const  { return derived().coeff(row,col); }
+    inline Scalar& coeffRef(Index row, Index col) { return derived().coeffRef(row,col); }
+
+    /** \see MatrixBase::copyCoeff(row,col)
+      */
+    template<typename Other>
+    EIGEN_STRONG_INLINE void copyCoeff(Index row, Index col, Other& other)
+    {
+      derived().coeffRef(row, col) = other.coeff(row, col);
+    }
+
+    inline Scalar operator()(Index row, Index col) const
+    {
+      check_coordinates(row, col);
+      return coeff(row,col);
+    }
+    inline Scalar& operator()(Index row, Index col)
+    {
+      check_coordinates(row, col);
+      return coeffRef(row,col);
+    }
+
+    #ifndef EIGEN_PARSED_BY_DOXYGEN
+    inline const Derived& derived() const { return *static_cast<const Derived*>(this); }
+    inline Derived& derived() { return *static_cast<Derived*>(this); }
+    #endif // not EIGEN_PARSED_BY_DOXYGEN
+
+    template<typename DenseDerived>
+    void evalTo(MatrixBase<DenseDerived> &other) const;
+    template<typename DenseDerived>
+    void evalToLazy(MatrixBase<DenseDerived> &other) const;
+
+    DenseMatrixType toDenseMatrix() const
+    {
+      DenseMatrixType res(rows(), cols());
+      evalToLazy(res);
+      return res;
+    }
+
+  protected:
+
+    void check_coordinates(Index row, Index col) const
+    {
+      EIGEN_ONLY_USED_FOR_DEBUG(row);
+      EIGEN_ONLY_USED_FOR_DEBUG(col);
+      eigen_assert(col>=0 && col<cols() && row>=0 && row<rows());
+      const int mode = int(Mode) & ~SelfAdjoint;
+      EIGEN_ONLY_USED_FOR_DEBUG(mode);
+      eigen_assert((mode==Upper && col>=row)
+                || (mode==Lower && col<=row)
+                || ((mode==StrictlyUpper || mode==UnitUpper) && col>row)
+                || ((mode==StrictlyLower || mode==UnitLower) && col<row));
+    }
+
+    #ifdef EIGEN_INTERNAL_DEBUGGING
+    void check_coordinates_internal(Index row, Index col) const
+    {
+      check_coordinates(row, col);
+    }
+    #else
+    void check_coordinates_internal(Index , Index ) const {}
+    #endif
+
+};
+
+/** \class TriangularView
+  * \ingroup Core_Module
+  *
+  * \brief Base class for triangular part in a matrix
+  *
+  * \param MatrixType the type of the object in which we are taking the triangular part
+  * \param Mode the kind of triangular matrix expression to construct. Can be #Upper,
+  *             #Lower, #UnitUpper, #UnitLower, #StrictlyUpper, or #StrictlyLower.
+  *             This is in fact a bit field; it must have either #Upper or #Lower, 
+  *             and additionnaly it may have #UnitDiag or #ZeroDiag or neither.
+  *
+  * This class represents a triangular part of a matrix, not necessarily square. Strictly speaking, for rectangular
+  * matrices one should speak of "trapezoid" parts. This class is the return type
+  * of MatrixBase::triangularView() and most of the time this is the only way it is used.
+  *
+  * \sa MatrixBase::triangularView()
+  */
+namespace internal {
+template<typename MatrixType, unsigned int _Mode>
+struct traits<TriangularView<MatrixType, _Mode> > : traits<MatrixType>
+{
+  typedef typename nested<MatrixType>::type MatrixTypeNested;
+  typedef typename remove_reference<MatrixTypeNested>::type MatrixTypeNestedNonRef;
+  typedef typename remove_all<MatrixTypeNested>::type MatrixTypeNestedCleaned;
+  typedef MatrixType ExpressionType;
+  typedef typename MatrixType::PlainObject DenseMatrixType;
+  enum {
+    Mode = _Mode,
+    Flags = (MatrixTypeNestedCleaned::Flags & (HereditaryBits) & (~(PacketAccessBit | DirectAccessBit | LinearAccessBit))) | Mode,
+    CoeffReadCost = MatrixTypeNestedCleaned::CoeffReadCost
+  };
+};
+}
+
+template<int Mode, bool LhsIsTriangular,
+         typename Lhs, bool LhsIsVector,
+         typename Rhs, bool RhsIsVector>
+struct TriangularProduct;
+
+template<typename _MatrixType, unsigned int _Mode> class TriangularView
+  : public TriangularBase<TriangularView<_MatrixType, _Mode> >
+{
+  public:
+
+    typedef TriangularBase<TriangularView> Base;
+    typedef typename internal::traits<TriangularView>::Scalar Scalar;
+
+    typedef _MatrixType MatrixType;
+    typedef typename internal::traits<TriangularView>::DenseMatrixType DenseMatrixType;
+    typedef DenseMatrixType PlainObject;
+
+  protected:
+    typedef typename internal::traits<TriangularView>::MatrixTypeNested MatrixTypeNested;
+    typedef typename internal::traits<TriangularView>::MatrixTypeNestedNonRef MatrixTypeNestedNonRef;
+    typedef typename internal::traits<TriangularView>::MatrixTypeNestedCleaned MatrixTypeNestedCleaned;
+
+    typedef typename internal::remove_all<typename MatrixType::ConjugateReturnType>::type MatrixConjugateReturnType;
+    
+  public:
+    using Base::evalToLazy;
+  
+
+    typedef typename internal::traits<TriangularView>::StorageKind StorageKind;
+    typedef typename internal::traits<TriangularView>::Index Index;
+
+    enum {
+      Mode = _Mode,
+      TransposeMode = (Mode & Upper ? Lower : 0)
+                    | (Mode & Lower ? Upper : 0)
+                    | (Mode & (UnitDiag))
+                    | (Mode & (ZeroDiag))
+    };
+
+    inline TriangularView(const MatrixType& matrix) : m_matrix(matrix)
+    {}
+
+    inline Index rows() const { return m_matrix.rows(); }
+    inline Index cols() const { return m_matrix.cols(); }
+    inline Index outerStride() const { return m_matrix.outerStride(); }
+    inline Index innerStride() const { return m_matrix.innerStride(); }
+
+    /** \sa MatrixBase::operator+=() */
+    template<typename Other> TriangularView&  operator+=(const DenseBase<Other>& other) { return *this = m_matrix + other.derived(); }
+    /** \sa MatrixBase::operator-=() */
+    template<typename Other> TriangularView&  operator-=(const DenseBase<Other>& other) { return *this = m_matrix - other.derived(); }
+    /** \sa MatrixBase::operator*=() */
+    TriangularView&  operator*=(const typename internal::traits<MatrixType>::Scalar& other) { return *this = m_matrix * other; }
+    /** \sa MatrixBase::operator/=() */
+    TriangularView&  operator/=(const typename internal::traits<MatrixType>::Scalar& other) { return *this = m_matrix / other; }
+
+    /** \sa MatrixBase::fill() */
+    void fill(const Scalar& value) { setConstant(value); }
+    /** \sa MatrixBase::setConstant() */
+    TriangularView& setConstant(const Scalar& value)
+    { return *this = MatrixType::Constant(rows(), cols(), value); }
+    /** \sa MatrixBase::setZero() */
+    TriangularView& setZero() { return setConstant(Scalar(0)); }
+    /** \sa MatrixBase::setOnes() */
+    TriangularView& setOnes() { return setConstant(Scalar(1)); }
+
+    /** \sa MatrixBase::coeff()
+      * \warning the coordinates must fit into the referenced triangular part
+      */
+    inline Scalar coeff(Index row, Index col) const
+    {
+      Base::check_coordinates_internal(row, col);
+      return m_matrix.coeff(row, col);
+    }
+
+    /** \sa MatrixBase::coeffRef()
+      * \warning the coordinates must fit into the referenced triangular part
+      */
+    inline Scalar& coeffRef(Index row, Index col)
+    {
+      Base::check_coordinates_internal(row, col);
+      return m_matrix.const_cast_derived().coeffRef(row, col);
+    }
+
+    const MatrixTypeNestedCleaned& nestedExpression() const { return m_matrix; }
+    MatrixTypeNestedCleaned& nestedExpression() { return *const_cast<MatrixTypeNestedCleaned*>(&m_matrix); }
+
+    /** Assigns a triangular matrix to a triangular part of a dense matrix */
+    template<typename OtherDerived>
+    TriangularView& operator=(const TriangularBase<OtherDerived>& other);
+
+    template<typename OtherDerived>
+    TriangularView& operator=(const MatrixBase<OtherDerived>& other);
+
+    TriangularView& operator=(const TriangularView& other)
+    { return *this = other.nestedExpression(); }
+
+    template<typename OtherDerived>
+    void lazyAssign(const TriangularBase<OtherDerived>& other);
+
+    template<typename OtherDerived>
+    void lazyAssign(const MatrixBase<OtherDerived>& other);
+
+    /** \sa MatrixBase::conjugate() */
+    inline TriangularView<MatrixConjugateReturnType,Mode> conjugate()
+    { return m_matrix.conjugate(); }
+    /** \sa MatrixBase::conjugate() const */
+    inline const TriangularView<MatrixConjugateReturnType,Mode> conjugate() const
+    { return m_matrix.conjugate(); }
+
+    /** \sa MatrixBase::adjoint() const */
+    inline const TriangularView<const typename MatrixType::AdjointReturnType,TransposeMode> adjoint() const
+    { return m_matrix.adjoint(); }
+
+    /** \sa MatrixBase::transpose() */
+    inline TriangularView<Transpose<MatrixType>,TransposeMode> transpose()
+    {
+      EIGEN_STATIC_ASSERT_LVALUE(MatrixType)
+      return m_matrix.const_cast_derived().transpose();
+    }
+    /** \sa MatrixBase::transpose() const */
+    inline const TriangularView<Transpose<MatrixType>,TransposeMode> transpose() const
+    {
+      return m_matrix.transpose();
+    }
+
+    /** Efficient triangular matrix times vector/matrix product */
+    template<typename OtherDerived>
+    TriangularProduct<Mode, true, MatrixType, false, OtherDerived, OtherDerived::ColsAtCompileTime==1>
+    operator*(const MatrixBase<OtherDerived>& rhs) const
+    {
+      return TriangularProduct
+              <Mode, true, MatrixType, false, OtherDerived, OtherDerived::ColsAtCompileTime==1>
+              (m_matrix, rhs.derived());
+    }
+
+    /** Efficient vector/matrix times triangular matrix product */
+    template<typename OtherDerived> friend
+    TriangularProduct<Mode, false, OtherDerived, OtherDerived::RowsAtCompileTime==1, MatrixType, false>
+    operator*(const MatrixBase<OtherDerived>& lhs, const TriangularView& rhs)
+    {
+      return TriangularProduct
+              <Mode, false, OtherDerived, OtherDerived::RowsAtCompileTime==1, MatrixType, false>
+              (lhs.derived(),rhs.m_matrix);
+    }
+
+    #ifdef EIGEN2_SUPPORT
+    template<typename OtherDerived>
+    struct eigen2_product_return_type
+    {
+      typedef typename TriangularView<MatrixType,Mode>::DenseMatrixType DenseMatrixType;
+      typedef typename OtherDerived::PlainObject::DenseType OtherPlainObject;
+      typedef typename ProductReturnType<DenseMatrixType, OtherPlainObject>::Type ProdRetType;
+      typedef typename ProdRetType::PlainObject type;
+    };
+    template<typename OtherDerived>
+    const typename eigen2_product_return_type<OtherDerived>::type
+    operator*(const EigenBase<OtherDerived>& rhs) const
+    {
+      typename OtherDerived::PlainObject::DenseType rhsPlainObject;
+      rhs.evalTo(rhsPlainObject);
+      return this->toDenseMatrix() * rhsPlainObject;
+    }
+    template<typename OtherMatrixType>
+    bool isApprox(const TriangularView<OtherMatrixType, Mode>& other, typename NumTraits<Scalar>::Real precision = NumTraits<Scalar>::dummy_precision()) const
+    {
+      return this->toDenseMatrix().isApprox(other.toDenseMatrix(), precision);
+    }
+    template<typename OtherDerived>
+    bool isApprox(const MatrixBase<OtherDerived>& other, typename NumTraits<Scalar>::Real precision = NumTraits<Scalar>::dummy_precision()) const
+    {
+      return this->toDenseMatrix().isApprox(other, precision);
+    }
+    #endif // EIGEN2_SUPPORT
+
+    template<int Side, typename Other>
+    inline const internal::triangular_solve_retval<Side,TriangularView, Other>
+    solve(const MatrixBase<Other>& other) const;
+
+    template<int Side, typename OtherDerived>
+    void solveInPlace(const MatrixBase<OtherDerived>& other) const;
+
+    template<typename Other>
+    inline const internal::triangular_solve_retval<OnTheLeft,TriangularView, Other> 
+    solve(const MatrixBase<Other>& other) const
+    { return solve<OnTheLeft>(other); }
+
+    template<typename OtherDerived>
+    void solveInPlace(const MatrixBase<OtherDerived>& other) const
+    { return solveInPlace<OnTheLeft>(other); }
+
+    const SelfAdjointView<MatrixTypeNestedNonRef,Mode> selfadjointView() const
+    {
+      EIGEN_STATIC_ASSERT((Mode&UnitDiag)==0,PROGRAMMING_ERROR);
+      return SelfAdjointView<MatrixTypeNestedNonRef,Mode>(m_matrix);
+    }
+    SelfAdjointView<MatrixTypeNestedNonRef,Mode> selfadjointView()
+    {
+      EIGEN_STATIC_ASSERT((Mode&UnitDiag)==0,PROGRAMMING_ERROR);
+      return SelfAdjointView<MatrixTypeNestedNonRef,Mode>(m_matrix);
+    }
+
+    template<typename OtherDerived>
+    void swap(TriangularBase<OtherDerived> const & other)
+    {
+      TriangularView<SwapWrapper<MatrixType>,Mode>(const_cast<MatrixType&>(m_matrix)).lazyAssign(other.derived());
+    }
+
+    template<typename OtherDerived>
+    void swap(MatrixBase<OtherDerived> const & other)
+    {
+      SwapWrapper<MatrixType> swaper(const_cast<MatrixType&>(m_matrix));
+      TriangularView<SwapWrapper<MatrixType>,Mode>(swaper).lazyAssign(other.derived());
+    }
+
+    Scalar determinant() const
+    {
+      if (Mode & UnitDiag)
+        return 1;
+      else if (Mode & ZeroDiag)
+        return 0;
+      else
+        return m_matrix.diagonal().prod();
+    }
+    
+    // TODO simplify the following:
+    template<typename ProductDerived, typename Lhs, typename Rhs>
+    EIGEN_STRONG_INLINE TriangularView& operator=(const ProductBase<ProductDerived, Lhs,Rhs>& other)
+    {
+      setZero();
+      return assignProduct(other.derived(),1);
+    }
+    
+    template<typename ProductDerived, typename Lhs, typename Rhs>
+    EIGEN_STRONG_INLINE TriangularView& operator+=(const ProductBase<ProductDerived, Lhs,Rhs>& other)
+    {
+      return assignProduct(other.derived(),1);
+    }
+    
+    template<typename ProductDerived, typename Lhs, typename Rhs>
+    EIGEN_STRONG_INLINE TriangularView& operator-=(const ProductBase<ProductDerived, Lhs,Rhs>& other)
+    {
+      return assignProduct(other.derived(),-1);
+    }
+    
+    
+    template<typename ProductDerived>
+    EIGEN_STRONG_INLINE TriangularView& operator=(const ScaledProduct<ProductDerived>& other)
+    {
+      setZero();
+      return assignProduct(other.derived(),other.alpha());
+    }
+    
+    template<typename ProductDerived>
+    EIGEN_STRONG_INLINE TriangularView& operator+=(const ScaledProduct<ProductDerived>& other)
+    {
+      return assignProduct(other.derived(),other.alpha());
+    }
+    
+    template<typename ProductDerived>
+    EIGEN_STRONG_INLINE TriangularView& operator-=(const ScaledProduct<ProductDerived>& other)
+    {
+      return assignProduct(other.derived(),-other.alpha());
+    }
+    
+  protected:
+    
+    template<typename ProductDerived, typename Lhs, typename Rhs>
+    EIGEN_STRONG_INLINE TriangularView& assignProduct(const ProductBase<ProductDerived, Lhs,Rhs>& prod, const Scalar& alpha);
+    
+    template<int Mode, bool LhsIsTriangular,
+         typename Lhs, bool LhsIsVector,
+         typename Rhs, bool RhsIsVector>
+    EIGEN_STRONG_INLINE TriangularView& assignProduct(const TriangularProduct<Mode, LhsIsTriangular, Lhs, LhsIsVector, Rhs, RhsIsVector>& prod, const Scalar& alpha)
+    {
+      lazyAssign(alpha*prod.eval());
+      return *this;
+    }
+
+    MatrixTypeNested m_matrix;
+};
+
+/***************************************************************************
+* Implementation of triangular evaluation/assignment
+***************************************************************************/
+
+namespace internal {
+
+template<typename Derived1, typename Derived2, unsigned int Mode, int UnrollCount, bool ClearOpposite>
+struct triangular_assignment_selector
+{
+  enum {
+    col = (UnrollCount-1) / Derived1::RowsAtCompileTime,
+    row = (UnrollCount-1) % Derived1::RowsAtCompileTime
+  };
+  
+  typedef typename Derived1::Scalar Scalar;
+
+  static inline void run(Derived1 &dst, const Derived2 &src)
+  {
+    triangular_assignment_selector<Derived1, Derived2, Mode, UnrollCount-1, ClearOpposite>::run(dst, src);
+
+    eigen_assert( Mode == Upper || Mode == Lower
+            || Mode == StrictlyUpper || Mode == StrictlyLower
+            || Mode == UnitUpper || Mode == UnitLower);
+    if((Mode == Upper && row <= col)
+    || (Mode == Lower && row >= col)
+    || (Mode == StrictlyUpper && row < col)
+    || (Mode == StrictlyLower && row > col)
+    || (Mode == UnitUpper && row < col)
+    || (Mode == UnitLower && row > col))
+      dst.copyCoeff(row, col, src);
+    else if(ClearOpposite)
+    {
+      if (Mode&UnitDiag && row==col)
+        dst.coeffRef(row, col) = Scalar(1);
+      else
+        dst.coeffRef(row, col) = Scalar(0);
+    }
+  }
+};
+
+// prevent buggy user code from causing an infinite recursion
+template<typename Derived1, typename Derived2, unsigned int Mode, bool ClearOpposite>
+struct triangular_assignment_selector<Derived1, Derived2, Mode, 0, ClearOpposite>
+{
+  static inline void run(Derived1 &, const Derived2 &) {}
+};
+
+template<typename Derived1, typename Derived2, bool ClearOpposite>
+struct triangular_assignment_selector<Derived1, Derived2, Upper, Dynamic, ClearOpposite>
+{
+  typedef typename Derived1::Index Index;
+  typedef typename Derived1::Scalar Scalar;
+  static inline void run(Derived1 &dst, const Derived2 &src)
+  {
+    for(Index j = 0; j < dst.cols(); ++j)
+    {
+      Index maxi = (std::min)(j, dst.rows()-1);
+      for(Index i = 0; i <= maxi; ++i)
+        dst.copyCoeff(i, j, src);
+      if (ClearOpposite)
+        for(Index i = maxi+1; i < dst.rows(); ++i)
+          dst.coeffRef(i, j) = Scalar(0);
+    }
+  }
+};
+
+template<typename Derived1, typename Derived2, bool ClearOpposite>
+struct triangular_assignment_selector<Derived1, Derived2, Lower, Dynamic, ClearOpposite>
+{
+  typedef typename Derived1::Index Index;
+  static inline void run(Derived1 &dst, const Derived2 &src)
+  {
+    for(Index j = 0; j < dst.cols(); ++j)
+    {
+      for(Index i = j; i < dst.rows(); ++i)
+        dst.copyCoeff(i, j, src);
+      Index maxi = (std::min)(j, dst.rows());
+      if (ClearOpposite)
+        for(Index i = 0; i < maxi; ++i)
+          dst.coeffRef(i, j) = static_cast<typename Derived1::Scalar>(0);
+    }
+  }
+};
+
+template<typename Derived1, typename Derived2, bool ClearOpposite>
+struct triangular_assignment_selector<Derived1, Derived2, StrictlyUpper, Dynamic, ClearOpposite>
+{
+  typedef typename Derived1::Index Index;
+  typedef typename Derived1::Scalar Scalar;
+  static inline void run(Derived1 &dst, const Derived2 &src)
+  {
+    for(Index j = 0; j < dst.cols(); ++j)
+    {
+      Index maxi = (std::min)(j, dst.rows());
+      for(Index i = 0; i < maxi; ++i)
+        dst.copyCoeff(i, j, src);
+      if (ClearOpposite)
+        for(Index i = maxi; i < dst.rows(); ++i)
+          dst.coeffRef(i, j) = Scalar(0);
+    }
+  }
+};
+
+template<typename Derived1, typename Derived2, bool ClearOpposite>
+struct triangular_assignment_selector<Derived1, Derived2, StrictlyLower, Dynamic, ClearOpposite>
+{
+  typedef typename Derived1::Index Index;
+  static inline void run(Derived1 &dst, const Derived2 &src)
+  {
+    for(Index j = 0; j < dst.cols(); ++j)
+    {
+      for(Index i = j+1; i < dst.rows(); ++i)
+        dst.copyCoeff(i, j, src);
+      Index maxi = (std::min)(j, dst.rows()-1);
+      if (ClearOpposite)
+        for(Index i = 0; i <= maxi; ++i)
+          dst.coeffRef(i, j) = static_cast<typename Derived1::Scalar>(0);
+    }
+  }
+};
+
+template<typename Derived1, typename Derived2, bool ClearOpposite>
+struct triangular_assignment_selector<Derived1, Derived2, UnitUpper, Dynamic, ClearOpposite>
+{
+  typedef typename Derived1::Index Index;
+  static inline void run(Derived1 &dst, const Derived2 &src)
+  {
+    for(Index j = 0; j < dst.cols(); ++j)
+    {
+      Index maxi = (std::min)(j, dst.rows());
+      for(Index i = 0; i < maxi; ++i)
+        dst.copyCoeff(i, j, src);
+      if (ClearOpposite)
+      {
+        for(Index i = maxi+1; i < dst.rows(); ++i)
+          dst.coeffRef(i, j) = 0;
+      }
+    }
+    dst.diagonal().setOnes();
+  }
+};
+template<typename Derived1, typename Derived2, bool ClearOpposite>
+struct triangular_assignment_selector<Derived1, Derived2, UnitLower, Dynamic, ClearOpposite>
+{
+  typedef typename Derived1::Index Index;
+  static inline void run(Derived1 &dst, const Derived2 &src)
+  {
+    for(Index j = 0; j < dst.cols(); ++j)
+    {
+      Index maxi = (std::min)(j, dst.rows());
+      for(Index i = maxi+1; i < dst.rows(); ++i)
+        dst.copyCoeff(i, j, src);
+      if (ClearOpposite)
+      {
+        for(Index i = 0; i < maxi; ++i)
+          dst.coeffRef(i, j) = 0;
+      }
+    }
+    dst.diagonal().setOnes();
+  }
+};
+
+} // end namespace internal
+
+// FIXME should we keep that possibility
+template<typename MatrixType, unsigned int Mode>
+template<typename OtherDerived>
+inline TriangularView<MatrixType, Mode>&
+TriangularView<MatrixType, Mode>::operator=(const MatrixBase<OtherDerived>& other)
+{
+  if(OtherDerived::Flags & EvalBeforeAssigningBit)
+  {
+    typename internal::plain_matrix_type<OtherDerived>::type other_evaluated(other.rows(), other.cols());
+    other_evaluated.template triangularView<Mode>().lazyAssign(other.derived());
+    lazyAssign(other_evaluated);
+  }
+  else
+    lazyAssign(other.derived());
+  return *this;
+}
+
+// FIXME should we keep that possibility
+template<typename MatrixType, unsigned int Mode>
+template<typename OtherDerived>
+void TriangularView<MatrixType, Mode>::lazyAssign(const MatrixBase<OtherDerived>& other)
+{
+  enum {
+    unroll = MatrixType::SizeAtCompileTime != Dynamic
+          && internal::traits<OtherDerived>::CoeffReadCost != Dynamic
+          && MatrixType::SizeAtCompileTime*internal::traits<OtherDerived>::CoeffReadCost/2 <= EIGEN_UNROLLING_LIMIT
+  };
+  eigen_assert(m_matrix.rows() == other.rows() && m_matrix.cols() == other.cols());
+
+  internal::triangular_assignment_selector
+    <MatrixType, OtherDerived, int(Mode),
+    unroll ? int(MatrixType::SizeAtCompileTime) : Dynamic,
+    false // do not change the opposite triangular part
+    >::run(m_matrix.const_cast_derived(), other.derived());
+}
+
+
+
+template<typename MatrixType, unsigned int Mode>
+template<typename OtherDerived>
+inline TriangularView<MatrixType, Mode>&
+TriangularView<MatrixType, Mode>::operator=(const TriangularBase<OtherDerived>& other)
+{
+  eigen_assert(Mode == int(OtherDerived::Mode));
+  if(internal::traits<OtherDerived>::Flags & EvalBeforeAssigningBit)
+  {
+    typename OtherDerived::DenseMatrixType other_evaluated(other.rows(), other.cols());
+    other_evaluated.template triangularView<Mode>().lazyAssign(other.derived().nestedExpression());
+    lazyAssign(other_evaluated);
+  }
+  else
+    lazyAssign(other.derived().nestedExpression());
+  return *this;
+}
+
+template<typename MatrixType, unsigned int Mode>
+template<typename OtherDerived>
+void TriangularView<MatrixType, Mode>::lazyAssign(const TriangularBase<OtherDerived>& other)
+{
+  enum {
+    unroll = MatrixType::SizeAtCompileTime != Dynamic
+                   && internal::traits<OtherDerived>::CoeffReadCost != Dynamic
+                   && MatrixType::SizeAtCompileTime * internal::traits<OtherDerived>::CoeffReadCost / 2
+                        <= EIGEN_UNROLLING_LIMIT
+  };
+  eigen_assert(m_matrix.rows() == other.rows() && m_matrix.cols() == other.cols());
+
+  internal::triangular_assignment_selector
+    <MatrixType, OtherDerived, int(Mode),
+    unroll ? int(MatrixType::SizeAtCompileTime) : Dynamic,
+    false // preserve the opposite triangular part
+    >::run(m_matrix.const_cast_derived(), other.derived().nestedExpression());
+}
+
+/***************************************************************************
+* Implementation of TriangularBase methods
+***************************************************************************/
+
+/** Assigns a triangular or selfadjoint matrix to a dense matrix.
+  * If the matrix is triangular, the opposite part is set to zero. */
+template<typename Derived>
+template<typename DenseDerived>
+void TriangularBase<Derived>::evalTo(MatrixBase<DenseDerived> &other) const
+{
+  if(internal::traits<Derived>::Flags & EvalBeforeAssigningBit)
+  {
+    typename internal::plain_matrix_type<Derived>::type other_evaluated(rows(), cols());
+    evalToLazy(other_evaluated);
+    other.derived().swap(other_evaluated);
+  }
+  else
+    evalToLazy(other.derived());
+}
+
+/** Assigns a triangular or selfadjoint matrix to a dense matrix.
+  * If the matrix is triangular, the opposite part is set to zero. */
+template<typename Derived>
+template<typename DenseDerived>
+void TriangularBase<Derived>::evalToLazy(MatrixBase<DenseDerived> &other) const
+{
+  enum {
+    unroll = DenseDerived::SizeAtCompileTime != Dynamic
+                   && internal::traits<Derived>::CoeffReadCost != Dynamic
+                   && DenseDerived::SizeAtCompileTime * internal::traits<Derived>::CoeffReadCost / 2
+                        <= EIGEN_UNROLLING_LIMIT
+  };
+  other.derived().resize(this->rows(), this->cols());
+
+  internal::triangular_assignment_selector
+    <DenseDerived, typename internal::traits<Derived>::MatrixTypeNestedCleaned, Derived::Mode,
+    unroll ? int(DenseDerived::SizeAtCompileTime) : Dynamic,
+    true // clear the opposite triangular part
+    >::run(other.derived(), derived().nestedExpression());
+}
+
+/***************************************************************************
+* Implementation of TriangularView methods
+***************************************************************************/
+
+/***************************************************************************
+* Implementation of MatrixBase methods
+***************************************************************************/
+
+#ifdef EIGEN2_SUPPORT
+
+// implementation of part<>(), including the SelfAdjoint case.
+
+namespace internal {
+template<typename MatrixType, unsigned int Mode>
+struct eigen2_part_return_type
+{
+  typedef TriangularView<MatrixType, Mode> type;
+};
+
+template<typename MatrixType>
+struct eigen2_part_return_type<MatrixType, SelfAdjoint>
+{
+  typedef SelfAdjointView<MatrixType, Upper> type;
+};
+}
+
+/** \deprecated use MatrixBase::triangularView() */
+template<typename Derived>
+template<unsigned int Mode>
+const typename internal::eigen2_part_return_type<Derived, Mode>::type MatrixBase<Derived>::part() const
+{
+  return derived();
+}
+
+/** \deprecated use MatrixBase::triangularView() */
+template<typename Derived>
+template<unsigned int Mode>
+typename internal::eigen2_part_return_type<Derived, Mode>::type MatrixBase<Derived>::part()
+{
+  return derived();
+}
+#endif
+
+/**
+  * \returns an expression of a triangular view extracted from the current matrix
+  *
+  * The parameter \a Mode can have the following values: \c #Upper, \c #StrictlyUpper, \c #UnitUpper,
+  * \c #Lower, \c #StrictlyLower, \c #UnitLower.
+  *
+  * Example: \include MatrixBase_extract.cpp
+  * Output: \verbinclude MatrixBase_extract.out
+  *
+  * \sa class TriangularView
+  */
+template<typename Derived>
+template<unsigned int Mode>
+typename MatrixBase<Derived>::template TriangularViewReturnType<Mode>::Type
+MatrixBase<Derived>::triangularView()
+{
+  return derived();
+}
+
+/** This is the const version of MatrixBase::triangularView() */
+template<typename Derived>
+template<unsigned int Mode>
+typename MatrixBase<Derived>::template ConstTriangularViewReturnType<Mode>::Type
+MatrixBase<Derived>::triangularView() const
+{
+  return derived();
+}
+
+/** \returns true if *this is approximately equal to an upper triangular matrix,
+  *          within the precision given by \a prec.
+  *
+  * \sa isLowerTriangular()
+  */
+template<typename Derived>
+bool MatrixBase<Derived>::isUpperTriangular(const RealScalar& prec) const
+{
+  using std::abs;
+  RealScalar maxAbsOnUpperPart = static_cast<RealScalar>(-1);
+  for(Index j = 0; j < cols(); ++j)
+  {
+    Index maxi = (std::min)(j, rows()-1);
+    for(Index i = 0; i <= maxi; ++i)
+    {
+      RealScalar absValue = abs(coeff(i,j));
+      if(absValue > maxAbsOnUpperPart) maxAbsOnUpperPart = absValue;
+    }
+  }
+  RealScalar threshold = maxAbsOnUpperPart * prec;
+  for(Index j = 0; j < cols(); ++j)
+    for(Index i = j+1; i < rows(); ++i)
+      if(abs(coeff(i, j)) > threshold) return false;
+  return true;
+}
+
+/** \returns true if *this is approximately equal to a lower triangular matrix,
+  *          within the precision given by \a prec.
+  *
+  * \sa isUpperTriangular()
+  */
+template<typename Derived>
+bool MatrixBase<Derived>::isLowerTriangular(const RealScalar& prec) const
+{
+  using std::abs;
+  RealScalar maxAbsOnLowerPart = static_cast<RealScalar>(-1);
+  for(Index j = 0; j < cols(); ++j)
+    for(Index i = j; i < rows(); ++i)
+    {
+      RealScalar absValue = abs(coeff(i,j));
+      if(absValue > maxAbsOnLowerPart) maxAbsOnLowerPart = absValue;
+    }
+  RealScalar threshold = maxAbsOnLowerPart * prec;
+  for(Index j = 1; j < cols(); ++j)
+  {
+    Index maxi = (std::min)(j, rows()-1);
+    for(Index i = 0; i < maxi; ++i)
+      if(abs(coeff(i, j)) > threshold) return false;
+  }
+  return true;
+}
+
+} // end namespace Eigen
+
+#endif // EIGEN_TRIANGULARMATRIX_H
\ No newline at end of file