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1 // This file is part of Eigen, a lightweight C++ template library
2 // for linear algebra.
3 //
4 // Copyright (C) 2008 Benoit Jacob <jacob.benoit.1@gmail.com>
5 // Copyright (C) 2008-2009 Gael Guennebaud <gael.guennebaud@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_TRIANGULARMATRIX_H
12 #define EIGEN_TRIANGULARMATRIX_H
13 
14 namespace Eigen {
15 
16 namespace internal {
17 
18 template<int Side, typename TriangularType, typename Rhs> struct triangular_solve_retval;
19 
20 }
21 
22 /** \internal
23   *
24   * \class TriangularBase
25   * \ingroup Core_Module
26   *
27   * \brief Base class for triangular part in a matrix
28   */
29 template<typename Derived> class TriangularBase : public EigenBase<Derived>
30 {
31   public:
32 
33     enum {
34       Mode = internal::traits<Derived>::Mode,
35       CoeffReadCost = internal::traits<Derived>::CoeffReadCost,
36       RowsAtCompileTime = internal::traits<Derived>::RowsAtCompileTime,
37       ColsAtCompileTime = internal::traits<Derived>::ColsAtCompileTime,
38       MaxRowsAtCompileTime = internal::traits<Derived>::MaxRowsAtCompileTime,
39       MaxColsAtCompileTime = internal::traits<Derived>::MaxColsAtCompileTime
40     };
41     typedef typename internal::traits<Derived>::Scalar Scalar;
42     typedef typename internal::traits<Derived>::StorageKind StorageKind;
43     typedef typename internal::traits<Derived>::Index Index;
44     typedef typename internal::traits<Derived>::DenseMatrixType DenseMatrixType;
45     typedef DenseMatrixType DenseType;
46 
TriangularBase()47     inline TriangularBase() { eigen_assert(!((Mode&UnitDiag) && (Mode&ZeroDiag))); }
48 
rows()49     inline Index rows() const { return derived().rows(); }
cols()50     inline Index cols() const { return derived().cols(); }
outerStride()51     inline Index outerStride() const { return derived().outerStride(); }
innerStride()52     inline Index innerStride() const { return derived().innerStride(); }
53 
coeff(Index row,Index col)54     inline Scalar coeff(Index row, Index col) const  { return derived().coeff(row,col); }
coeffRef(Index row,Index col)55     inline Scalar& coeffRef(Index row, Index col) { return derived().coeffRef(row,col); }
56 
57     /** \see MatrixBase::copyCoeff(row,col)
58       */
59     template<typename Other>
copyCoeff(Index row,Index col,Other & other)60     EIGEN_STRONG_INLINE void copyCoeff(Index row, Index col, Other& other)
61     {
62       derived().coeffRef(row, col) = other.coeff(row, col);
63     }
64 
operator()65     inline Scalar operator()(Index row, Index col) const
66     {
67       check_coordinates(row, col);
68       return coeff(row,col);
69     }
operator()70     inline Scalar& operator()(Index row, Index col)
71     {
72       check_coordinates(row, col);
73       return coeffRef(row,col);
74     }
75 
76     #ifndef EIGEN_PARSED_BY_DOXYGEN
derived()77     inline const Derived& derived() const { return *static_cast<const Derived*>(this); }
derived()78     inline Derived& derived() { return *static_cast<Derived*>(this); }
79     #endif // not EIGEN_PARSED_BY_DOXYGEN
80 
81     template<typename DenseDerived>
82     void evalTo(MatrixBase<DenseDerived> &other) const;
83     template<typename DenseDerived>
84     void evalToLazy(MatrixBase<DenseDerived> &other) const;
85 
toDenseMatrix()86     DenseMatrixType toDenseMatrix() const
87     {
88       DenseMatrixType res(rows(), cols());
89       evalToLazy(res);
90       return res;
91     }
92 
93   protected:
94 
check_coordinates(Index row,Index col)95     void check_coordinates(Index row, Index col) const
96     {
97       EIGEN_ONLY_USED_FOR_DEBUG(row);
98       EIGEN_ONLY_USED_FOR_DEBUG(col);
99       eigen_assert(col>=0 && col<cols() && row>=0 && row<rows());
100       const int mode = int(Mode) & ~SelfAdjoint;
101       EIGEN_ONLY_USED_FOR_DEBUG(mode);
102       eigen_assert((mode==Upper && col>=row)
103                 || (mode==Lower && col<=row)
104                 || ((mode==StrictlyUpper || mode==UnitUpper) && col>row)
105                 || ((mode==StrictlyLower || mode==UnitLower) && col<row));
106     }
107 
108     #ifdef EIGEN_INTERNAL_DEBUGGING
check_coordinates_internal(Index row,Index col)109     void check_coordinates_internal(Index row, Index col) const
110     {
111       check_coordinates(row, col);
112     }
113     #else
check_coordinates_internal(Index,Index)114     void check_coordinates_internal(Index , Index ) const {}
115     #endif
116 
117 };
118 
119 /** \class TriangularView
120   * \ingroup Core_Module
121   *
122   * \brief Base class for triangular part in a matrix
123   *
124   * \param MatrixType the type of the object in which we are taking the triangular part
125   * \param Mode the kind of triangular matrix expression to construct. Can be #Upper,
126   *             #Lower, #UnitUpper, #UnitLower, #StrictlyUpper, or #StrictlyLower.
127   *             This is in fact a bit field; it must have either #Upper or #Lower,
128   *             and additionnaly it may have #UnitDiag or #ZeroDiag or neither.
129   *
130   * This class represents a triangular part of a matrix, not necessarily square. Strictly speaking, for rectangular
131   * matrices one should speak of "trapezoid" parts. This class is the return type
132   * of MatrixBase::triangularView() and most of the time this is the only way it is used.
133   *
134   * \sa MatrixBase::triangularView()
135   */
136 namespace internal {
137 template<typename MatrixType, unsigned int _Mode>
138 struct traits<TriangularView<MatrixType, _Mode> > : traits<MatrixType>
139 {
140   typedef typename nested<MatrixType>::type MatrixTypeNested;
141   typedef typename remove_reference<MatrixTypeNested>::type MatrixTypeNestedNonRef;
142   typedef typename remove_all<MatrixTypeNested>::type MatrixTypeNestedCleaned;
143   typedef MatrixType ExpressionType;
144   typedef typename MatrixType::PlainObject DenseMatrixType;
145   enum {
146     Mode = _Mode,
147     Flags = (MatrixTypeNestedCleaned::Flags & (HereditaryBits) & (~(PacketAccessBit | DirectAccessBit | LinearAccessBit))) | Mode,
148     CoeffReadCost = MatrixTypeNestedCleaned::CoeffReadCost
149   };
150 };
151 }
152 
153 template<int Mode, bool LhsIsTriangular,
154          typename Lhs, bool LhsIsVector,
155          typename Rhs, bool RhsIsVector>
156 struct TriangularProduct;
157 
158 template<typename _MatrixType, unsigned int _Mode> class TriangularView
159   : public TriangularBase<TriangularView<_MatrixType, _Mode> >
160 {
161   public:
162 
163     typedef TriangularBase<TriangularView> Base;
164     typedef typename internal::traits<TriangularView>::Scalar Scalar;
165 
166     typedef _MatrixType MatrixType;
167     typedef typename internal::traits<TriangularView>::DenseMatrixType DenseMatrixType;
168     typedef DenseMatrixType PlainObject;
169 
170   protected:
171     typedef typename internal::traits<TriangularView>::MatrixTypeNested MatrixTypeNested;
172     typedef typename internal::traits<TriangularView>::MatrixTypeNestedNonRef MatrixTypeNestedNonRef;
173     typedef typename internal::traits<TriangularView>::MatrixTypeNestedCleaned MatrixTypeNestedCleaned;
174 
175     typedef typename internal::remove_all<typename MatrixType::ConjugateReturnType>::type MatrixConjugateReturnType;
176 
177   public:
178     using Base::evalToLazy;
179 
180 
181     typedef typename internal::traits<TriangularView>::StorageKind StorageKind;
182     typedef typename internal::traits<TriangularView>::Index Index;
183 
184     enum {
185       Mode = _Mode,
186       TransposeMode = (Mode & Upper ? Lower : 0)
187                     | (Mode & Lower ? Upper : 0)
188                     | (Mode & (UnitDiag))
189                     | (Mode & (ZeroDiag))
190     };
191 
192     inline TriangularView(const MatrixType& matrix) : m_matrix(matrix)
193     {}
194 
195     inline Index rows() const { return m_matrix.rows(); }
196     inline Index cols() const { return m_matrix.cols(); }
197     inline Index outerStride() const { return m_matrix.outerStride(); }
198     inline Index innerStride() const { return m_matrix.innerStride(); }
199 
200     /** \sa MatrixBase::operator+=() */
201     template<typename Other> TriangularView&  operator+=(const DenseBase<Other>& other) { return *this = m_matrix + other.derived(); }
202     /** \sa MatrixBase::operator-=() */
203     template<typename Other> TriangularView&  operator-=(const DenseBase<Other>& other) { return *this = m_matrix - other.derived(); }
204     /** \sa MatrixBase::operator*=() */
205     TriangularView&  operator*=(const typename internal::traits<MatrixType>::Scalar& other) { return *this = m_matrix * other; }
206     /** \sa MatrixBase::operator/=() */
207     TriangularView&  operator/=(const typename internal::traits<MatrixType>::Scalar& other) { return *this = m_matrix / other; }
208 
209     /** \sa MatrixBase::fill() */
210     void fill(const Scalar& value) { setConstant(value); }
211     /** \sa MatrixBase::setConstant() */
212     TriangularView& setConstant(const Scalar& value)
213     { return *this = MatrixType::Constant(rows(), cols(), value); }
214     /** \sa MatrixBase::setZero() */
215     TriangularView& setZero() { return setConstant(Scalar(0)); }
216     /** \sa MatrixBase::setOnes() */
217     TriangularView& setOnes() { return setConstant(Scalar(1)); }
218 
219     /** \sa MatrixBase::coeff()
220       * \warning the coordinates must fit into the referenced triangular part
221       */
222     inline Scalar coeff(Index row, Index col) const
223     {
224       Base::check_coordinates_internal(row, col);
225       return m_matrix.coeff(row, col);
226     }
227 
228     /** \sa MatrixBase::coeffRef()
229       * \warning the coordinates must fit into the referenced triangular part
230       */
231     inline Scalar& coeffRef(Index row, Index col)
232     {
233       Base::check_coordinates_internal(row, col);
234       return m_matrix.const_cast_derived().coeffRef(row, col);
235     }
236 
237     const MatrixTypeNestedCleaned& nestedExpression() const { return m_matrix; }
238     MatrixTypeNestedCleaned& nestedExpression() { return *const_cast<MatrixTypeNestedCleaned*>(&m_matrix); }
239 
240     /** Assigns a triangular matrix to a triangular part of a dense matrix */
241     template<typename OtherDerived>
242     TriangularView& operator=(const TriangularBase<OtherDerived>& other);
243 
244     template<typename OtherDerived>
245     TriangularView& operator=(const MatrixBase<OtherDerived>& other);
246 
247     TriangularView& operator=(const TriangularView& other)
248     { return *this = other.nestedExpression(); }
249 
250     template<typename OtherDerived>
251     void lazyAssign(const TriangularBase<OtherDerived>& other);
252 
253     template<typename OtherDerived>
254     void lazyAssign(const MatrixBase<OtherDerived>& other);
255 
256     /** \sa MatrixBase::conjugate() */
257     inline TriangularView<MatrixConjugateReturnType,Mode> conjugate()
258     { return m_matrix.conjugate(); }
259     /** \sa MatrixBase::conjugate() const */
260     inline const TriangularView<MatrixConjugateReturnType,Mode> conjugate() const
261     { return m_matrix.conjugate(); }
262 
263     /** \sa MatrixBase::adjoint() const */
264     inline const TriangularView<const typename MatrixType::AdjointReturnType,TransposeMode> adjoint() const
265     { return m_matrix.adjoint(); }
266 
267     /** \sa MatrixBase::transpose() */
268     inline TriangularView<Transpose<MatrixType>,TransposeMode> transpose()
269     {
270       EIGEN_STATIC_ASSERT_LVALUE(MatrixType)
271       return m_matrix.const_cast_derived().transpose();
272     }
273     /** \sa MatrixBase::transpose() const */
274     inline const TriangularView<Transpose<MatrixType>,TransposeMode> transpose() const
275     {
276       return m_matrix.transpose();
277     }
278 
279     /** Efficient triangular matrix times vector/matrix product */
280     template<typename OtherDerived>
281     TriangularProduct<Mode,true,MatrixType,false,OtherDerived, OtherDerived::IsVectorAtCompileTime>
282     operator*(const MatrixBase<OtherDerived>& rhs) const
283     {
284       return TriangularProduct
285               <Mode,true,MatrixType,false,OtherDerived,OtherDerived::IsVectorAtCompileTime>
286               (m_matrix, rhs.derived());
287     }
288 
289     /** Efficient vector/matrix times triangular matrix product */
290     template<typename OtherDerived> friend
291     TriangularProduct<Mode,false,OtherDerived,OtherDerived::IsVectorAtCompileTime,MatrixType,false>
292     operator*(const MatrixBase<OtherDerived>& lhs, const TriangularView& rhs)
293     {
294       return TriangularProduct
295               <Mode,false,OtherDerived,OtherDerived::IsVectorAtCompileTime,MatrixType,false>
296               (lhs.derived(),rhs.m_matrix);
297     }
298 
299     #ifdef EIGEN2_SUPPORT
300     template<typename OtherDerived>
301     struct eigen2_product_return_type
302     {
303       typedef typename TriangularView<MatrixType,Mode>::DenseMatrixType DenseMatrixType;
304       typedef typename OtherDerived::PlainObject::DenseType OtherPlainObject;
305       typedef typename ProductReturnType<DenseMatrixType, OtherPlainObject>::Type ProdRetType;
306       typedef typename ProdRetType::PlainObject type;
307     };
308     template<typename OtherDerived>
309     const typename eigen2_product_return_type<OtherDerived>::type
310     operator*(const EigenBase<OtherDerived>& rhs) const
311     {
312       typename OtherDerived::PlainObject::DenseType rhsPlainObject;
313       rhs.evalTo(rhsPlainObject);
314       return this->toDenseMatrix() * rhsPlainObject;
315     }
316     template<typename OtherMatrixType>
317     bool isApprox(const TriangularView<OtherMatrixType, Mode>& other, typename NumTraits<Scalar>::Real precision = NumTraits<Scalar>::dummy_precision()) const
318     {
319       return this->toDenseMatrix().isApprox(other.toDenseMatrix(), precision);
320     }
321     template<typename OtherDerived>
322     bool isApprox(const MatrixBase<OtherDerived>& other, typename NumTraits<Scalar>::Real precision = NumTraits<Scalar>::dummy_precision()) const
323     {
324       return this->toDenseMatrix().isApprox(other, precision);
325     }
326     #endif // EIGEN2_SUPPORT
327 
328     template<int Side, typename Other>
329     inline const internal::triangular_solve_retval<Side,TriangularView, Other>
330     solve(const MatrixBase<Other>& other) const;
331 
332     template<int Side, typename OtherDerived>
333     void solveInPlace(const MatrixBase<OtherDerived>& other) const;
334 
335     template<typename Other>
336     inline const internal::triangular_solve_retval<OnTheLeft,TriangularView, Other>
337     solve(const MatrixBase<Other>& other) const
338     { return solve<OnTheLeft>(other); }
339 
340     template<typename OtherDerived>
341     void solveInPlace(const MatrixBase<OtherDerived>& other) const
342     { return solveInPlace<OnTheLeft>(other); }
343 
344     const SelfAdjointView<MatrixTypeNestedNonRef,Mode> selfadjointView() const
345     {
346       EIGEN_STATIC_ASSERT((Mode&UnitDiag)==0,PROGRAMMING_ERROR);
347       return SelfAdjointView<MatrixTypeNestedNonRef,Mode>(m_matrix);
348     }
349     SelfAdjointView<MatrixTypeNestedNonRef,Mode> selfadjointView()
350     {
351       EIGEN_STATIC_ASSERT((Mode&UnitDiag)==0,PROGRAMMING_ERROR);
352       return SelfAdjointView<MatrixTypeNestedNonRef,Mode>(m_matrix);
353     }
354 
355     template<typename OtherDerived>
356     void swap(TriangularBase<OtherDerived> const & other)
357     {
358       TriangularView<SwapWrapper<MatrixType>,Mode>(const_cast<MatrixType&>(m_matrix)).lazyAssign(other.derived());
359     }
360 
361     template<typename OtherDerived>
362     void swap(MatrixBase<OtherDerived> const & other)
363     {
364       SwapWrapper<MatrixType> swaper(const_cast<MatrixType&>(m_matrix));
365       TriangularView<SwapWrapper<MatrixType>,Mode>(swaper).lazyAssign(other.derived());
366     }
367 
368     Scalar determinant() const
369     {
370       if (Mode & UnitDiag)
371         return 1;
372       else if (Mode & ZeroDiag)
373         return 0;
374       else
375         return m_matrix.diagonal().prod();
376     }
377 
378     // TODO simplify the following:
379     template<typename ProductDerived, typename Lhs, typename Rhs>
380     EIGEN_STRONG_INLINE TriangularView& operator=(const ProductBase<ProductDerived, Lhs,Rhs>& other)
381     {
382       setZero();
383       return assignProduct(other,1);
384     }
385 
386     template<typename ProductDerived, typename Lhs, typename Rhs>
387     EIGEN_STRONG_INLINE TriangularView& operator+=(const ProductBase<ProductDerived, Lhs,Rhs>& other)
388     {
389       return assignProduct(other,1);
390     }
391 
392     template<typename ProductDerived, typename Lhs, typename Rhs>
393     EIGEN_STRONG_INLINE TriangularView& operator-=(const ProductBase<ProductDerived, Lhs,Rhs>& other)
394     {
395       return assignProduct(other,-1);
396     }
397 
398 
399     template<typename ProductDerived>
400     EIGEN_STRONG_INLINE TriangularView& operator=(const ScaledProduct<ProductDerived>& other)
401     {
402       setZero();
403       return assignProduct(other,other.alpha());
404     }
405 
406     template<typename ProductDerived>
407     EIGEN_STRONG_INLINE TriangularView& operator+=(const ScaledProduct<ProductDerived>& other)
408     {
409       return assignProduct(other,other.alpha());
410     }
411 
412     template<typename ProductDerived>
413     EIGEN_STRONG_INLINE TriangularView& operator-=(const ScaledProduct<ProductDerived>& other)
414     {
415       return assignProduct(other,-other.alpha());
416     }
417 
418   protected:
419 
420     template<typename ProductDerived, typename Lhs, typename Rhs>
421     EIGEN_STRONG_INLINE TriangularView& assignProduct(const ProductBase<ProductDerived, Lhs,Rhs>& prod, const Scalar& alpha);
422 
423     MatrixTypeNested m_matrix;
424 };
425 
426 /***************************************************************************
427 * Implementation of triangular evaluation/assignment
428 ***************************************************************************/
429 
430 namespace internal {
431 
432 template<typename Derived1, typename Derived2, unsigned int Mode, int UnrollCount, bool ClearOpposite>
433 struct triangular_assignment_selector
434 {
435   enum {
436     col = (UnrollCount-1) / Derived1::RowsAtCompileTime,
437     row = (UnrollCount-1) % Derived1::RowsAtCompileTime
438   };
439 
440   typedef typename Derived1::Scalar Scalar;
441 
442   static inline void run(Derived1 &dst, const Derived2 &src)
443   {
444     triangular_assignment_selector<Derived1, Derived2, Mode, UnrollCount-1, ClearOpposite>::run(dst, src);
445 
446     eigen_assert( Mode == Upper || Mode == Lower
447             || Mode == StrictlyUpper || Mode == StrictlyLower
448             || Mode == UnitUpper || Mode == UnitLower);
449     if((Mode == Upper && row <= col)
450     || (Mode == Lower && row >= col)
451     || (Mode == StrictlyUpper && row < col)
452     || (Mode == StrictlyLower && row > col)
453     || (Mode == UnitUpper && row < col)
454     || (Mode == UnitLower && row > col))
455       dst.copyCoeff(row, col, src);
456     else if(ClearOpposite)
457     {
458       if (Mode&UnitDiag && row==col)
459         dst.coeffRef(row, col) = Scalar(1);
460       else
461         dst.coeffRef(row, col) = Scalar(0);
462     }
463   }
464 };
465 
466 // prevent buggy user code from causing an infinite recursion
467 template<typename Derived1, typename Derived2, unsigned int Mode, bool ClearOpposite>
468 struct triangular_assignment_selector<Derived1, Derived2, Mode, 0, ClearOpposite>
469 {
470   static inline void run(Derived1 &, const Derived2 &) {}
471 };
472 
473 template<typename Derived1, typename Derived2, bool ClearOpposite>
474 struct triangular_assignment_selector<Derived1, Derived2, Upper, Dynamic, ClearOpposite>
475 {
476   typedef typename Derived1::Index Index;
477   typedef typename Derived1::Scalar Scalar;
478   static inline void run(Derived1 &dst, const Derived2 &src)
479   {
480     for(Index j = 0; j < dst.cols(); ++j)
481     {
482       Index maxi = (std::min)(j, dst.rows()-1);
483       for(Index i = 0; i <= maxi; ++i)
484         dst.copyCoeff(i, j, src);
485       if (ClearOpposite)
486         for(Index i = maxi+1; i < dst.rows(); ++i)
487           dst.coeffRef(i, j) = Scalar(0);
488     }
489   }
490 };
491 
492 template<typename Derived1, typename Derived2, bool ClearOpposite>
493 struct triangular_assignment_selector<Derived1, Derived2, Lower, Dynamic, ClearOpposite>
494 {
495   typedef typename Derived1::Index Index;
496   static inline void run(Derived1 &dst, const Derived2 &src)
497   {
498     for(Index j = 0; j < dst.cols(); ++j)
499     {
500       for(Index i = j; i < dst.rows(); ++i)
501         dst.copyCoeff(i, j, src);
502       Index maxi = (std::min)(j, dst.rows());
503       if (ClearOpposite)
504         for(Index i = 0; i < maxi; ++i)
505           dst.coeffRef(i, j) = static_cast<typename Derived1::Scalar>(0);
506     }
507   }
508 };
509 
510 template<typename Derived1, typename Derived2, bool ClearOpposite>
511 struct triangular_assignment_selector<Derived1, Derived2, StrictlyUpper, Dynamic, ClearOpposite>
512 {
513   typedef typename Derived1::Index Index;
514   static inline void run(Derived1 &dst, const Derived2 &src)
515   {
516     for(Index j = 0; j < dst.cols(); ++j)
517     {
518       Index maxi = (std::min)(j, dst.rows());
519       for(Index i = 0; i < maxi; ++i)
520         dst.copyCoeff(i, j, src);
521       if (ClearOpposite)
522         for(Index i = maxi; i < dst.rows(); ++i)
523           dst.coeffRef(i, j) = 0;
524     }
525   }
526 };
527 
528 template<typename Derived1, typename Derived2, bool ClearOpposite>
529 struct triangular_assignment_selector<Derived1, Derived2, StrictlyLower, Dynamic, ClearOpposite>
530 {
531   typedef typename Derived1::Index Index;
532   static inline void run(Derived1 &dst, const Derived2 &src)
533   {
534     for(Index j = 0; j < dst.cols(); ++j)
535     {
536       for(Index i = j+1; i < dst.rows(); ++i)
537         dst.copyCoeff(i, j, src);
538       Index maxi = (std::min)(j, dst.rows()-1);
539       if (ClearOpposite)
540         for(Index i = 0; i <= maxi; ++i)
541           dst.coeffRef(i, j) = static_cast<typename Derived1::Scalar>(0);
542     }
543   }
544 };
545 
546 template<typename Derived1, typename Derived2, bool ClearOpposite>
547 struct triangular_assignment_selector<Derived1, Derived2, UnitUpper, Dynamic, ClearOpposite>
548 {
549   typedef typename Derived1::Index Index;
550   static inline void run(Derived1 &dst, const Derived2 &src)
551   {
552     for(Index j = 0; j < dst.cols(); ++j)
553     {
554       Index maxi = (std::min)(j, dst.rows());
555       for(Index i = 0; i < maxi; ++i)
556         dst.copyCoeff(i, j, src);
557       if (ClearOpposite)
558       {
559         for(Index i = maxi+1; i < dst.rows(); ++i)
560           dst.coeffRef(i, j) = 0;
561       }
562     }
563     dst.diagonal().setOnes();
564   }
565 };
566 template<typename Derived1, typename Derived2, bool ClearOpposite>
567 struct triangular_assignment_selector<Derived1, Derived2, UnitLower, Dynamic, ClearOpposite>
568 {
569   typedef typename Derived1::Index Index;
570   static inline void run(Derived1 &dst, const Derived2 &src)
571   {
572     for(Index j = 0; j < dst.cols(); ++j)
573     {
574       Index maxi = (std::min)(j, dst.rows());
575       for(Index i = maxi+1; i < dst.rows(); ++i)
576         dst.copyCoeff(i, j, src);
577       if (ClearOpposite)
578       {
579         for(Index i = 0; i < maxi; ++i)
580           dst.coeffRef(i, j) = 0;
581       }
582     }
583     dst.diagonal().setOnes();
584   }
585 };
586 
587 } // end namespace internal
588 
589 // FIXME should we keep that possibility
590 template<typename MatrixType, unsigned int Mode>
591 template<typename OtherDerived>
592 inline TriangularView<MatrixType, Mode>&
593 TriangularView<MatrixType, Mode>::operator=(const MatrixBase<OtherDerived>& other)
594 {
595   if(OtherDerived::Flags & EvalBeforeAssigningBit)
596   {
597     typename internal::plain_matrix_type<OtherDerived>::type other_evaluated(other.rows(), other.cols());
598     other_evaluated.template triangularView<Mode>().lazyAssign(other.derived());
599     lazyAssign(other_evaluated);
600   }
601   else
602     lazyAssign(other.derived());
603   return *this;
604 }
605 
606 // FIXME should we keep that possibility
607 template<typename MatrixType, unsigned int Mode>
608 template<typename OtherDerived>
609 void TriangularView<MatrixType, Mode>::lazyAssign(const MatrixBase<OtherDerived>& other)
610 {
611   enum {
612     unroll = MatrixType::SizeAtCompileTime != Dynamic
613           && internal::traits<OtherDerived>::CoeffReadCost != Dynamic
614           && MatrixType::SizeAtCompileTime*internal::traits<OtherDerived>::CoeffReadCost/2 <= EIGEN_UNROLLING_LIMIT
615   };
616   eigen_assert(m_matrix.rows() == other.rows() && m_matrix.cols() == other.cols());
617 
618   internal::triangular_assignment_selector
619     <MatrixType, OtherDerived, int(Mode),
620     unroll ? int(MatrixType::SizeAtCompileTime) : Dynamic,
621     false // do not change the opposite triangular part
622     >::run(m_matrix.const_cast_derived(), other.derived());
623 }
624 
625 
626 
627 template<typename MatrixType, unsigned int Mode>
628 template<typename OtherDerived>
629 inline TriangularView<MatrixType, Mode>&
630 TriangularView<MatrixType, Mode>::operator=(const TriangularBase<OtherDerived>& other)
631 {
632   eigen_assert(Mode == int(OtherDerived::Mode));
633   if(internal::traits<OtherDerived>::Flags & EvalBeforeAssigningBit)
634   {
635     typename OtherDerived::DenseMatrixType other_evaluated(other.rows(), other.cols());
636     other_evaluated.template triangularView<Mode>().lazyAssign(other.derived().nestedExpression());
637     lazyAssign(other_evaluated);
638   }
639   else
640     lazyAssign(other.derived().nestedExpression());
641   return *this;
642 }
643 
644 template<typename MatrixType, unsigned int Mode>
645 template<typename OtherDerived>
646 void TriangularView<MatrixType, Mode>::lazyAssign(const TriangularBase<OtherDerived>& other)
647 {
648   enum {
649     unroll = MatrixType::SizeAtCompileTime != Dynamic
650                    && internal::traits<OtherDerived>::CoeffReadCost != Dynamic
651                    && MatrixType::SizeAtCompileTime * internal::traits<OtherDerived>::CoeffReadCost / 2
652                         <= EIGEN_UNROLLING_LIMIT
653   };
654   eigen_assert(m_matrix.rows() == other.rows() && m_matrix.cols() == other.cols());
655 
656   internal::triangular_assignment_selector
657     <MatrixType, OtherDerived, int(Mode),
658     unroll ? int(MatrixType::SizeAtCompileTime) : Dynamic,
659     false // preserve the opposite triangular part
660     >::run(m_matrix.const_cast_derived(), other.derived().nestedExpression());
661 }
662 
663 /***************************************************************************
664 * Implementation of TriangularBase methods
665 ***************************************************************************/
666 
667 /** Assigns a triangular or selfadjoint matrix to a dense matrix.
668   * If the matrix is triangular, the opposite part is set to zero. */
669 template<typename Derived>
670 template<typename DenseDerived>
671 void TriangularBase<Derived>::evalTo(MatrixBase<DenseDerived> &other) const
672 {
673   if(internal::traits<Derived>::Flags & EvalBeforeAssigningBit)
674   {
675     typename internal::plain_matrix_type<Derived>::type other_evaluated(rows(), cols());
676     evalToLazy(other_evaluated);
677     other.derived().swap(other_evaluated);
678   }
679   else
680     evalToLazy(other.derived());
681 }
682 
683 /** Assigns a triangular or selfadjoint matrix to a dense matrix.
684   * If the matrix is triangular, the opposite part is set to zero. */
685 template<typename Derived>
686 template<typename DenseDerived>
687 void TriangularBase<Derived>::evalToLazy(MatrixBase<DenseDerived> &other) const
688 {
689   enum {
690     unroll = DenseDerived::SizeAtCompileTime != Dynamic
691                    && internal::traits<Derived>::CoeffReadCost != Dynamic
692                    && DenseDerived::SizeAtCompileTime * internal::traits<Derived>::CoeffReadCost / 2
693                         <= EIGEN_UNROLLING_LIMIT
694   };
695   other.derived().resize(this->rows(), this->cols());
696 
697   internal::triangular_assignment_selector
698     <DenseDerived, typename internal::traits<Derived>::MatrixTypeNestedCleaned, Derived::Mode,
699     unroll ? int(DenseDerived::SizeAtCompileTime) : Dynamic,
700     true // clear the opposite triangular part
701     >::run(other.derived(), derived().nestedExpression());
702 }
703 
704 /***************************************************************************
705 * Implementation of TriangularView methods
706 ***************************************************************************/
707 
708 /***************************************************************************
709 * Implementation of MatrixBase methods
710 ***************************************************************************/
711 
712 #ifdef EIGEN2_SUPPORT
713 
714 // implementation of part<>(), including the SelfAdjoint case.
715 
716 namespace internal {
717 template<typename MatrixType, unsigned int Mode>
718 struct eigen2_part_return_type
719 {
720   typedef TriangularView<MatrixType, Mode> type;
721 };
722 
723 template<typename MatrixType>
724 struct eigen2_part_return_type<MatrixType, SelfAdjoint>
725 {
726   typedef SelfAdjointView<MatrixType, Upper> type;
727 };
728 }
729 
730 /** \deprecated use MatrixBase::triangularView() */
731 template<typename Derived>
732 template<unsigned int Mode>
733 const typename internal::eigen2_part_return_type<Derived, Mode>::type MatrixBase<Derived>::part() const
734 {
735   return derived();
736 }
737 
738 /** \deprecated use MatrixBase::triangularView() */
739 template<typename Derived>
740 template<unsigned int Mode>
741 typename internal::eigen2_part_return_type<Derived, Mode>::type MatrixBase<Derived>::part()
742 {
743   return derived();
744 }
745 #endif
746 
747 /**
748   * \returns an expression of a triangular view extracted from the current matrix
749   *
750   * The parameter \a Mode can have the following values: \c #Upper, \c #StrictlyUpper, \c #UnitUpper,
751   * \c #Lower, \c #StrictlyLower, \c #UnitLower.
752   *
753   * Example: \include MatrixBase_extract.cpp
754   * Output: \verbinclude MatrixBase_extract.out
755   *
756   * \sa class TriangularView
757   */
758 template<typename Derived>
759 template<unsigned int Mode>
760 typename MatrixBase<Derived>::template TriangularViewReturnType<Mode>::Type
761 MatrixBase<Derived>::triangularView()
762 {
763   return derived();
764 }
765 
766 /** This is the const version of MatrixBase::triangularView() */
767 template<typename Derived>
768 template<unsigned int Mode>
769 typename MatrixBase<Derived>::template ConstTriangularViewReturnType<Mode>::Type
770 MatrixBase<Derived>::triangularView() const
771 {
772   return derived();
773 }
774 
775 /** \returns true if *this is approximately equal to an upper triangular matrix,
776   *          within the precision given by \a prec.
777   *
778   * \sa isLowerTriangular()
779   */
780 template<typename Derived>
781 bool MatrixBase<Derived>::isUpperTriangular(RealScalar prec) const
782 {
783   RealScalar maxAbsOnUpperPart = static_cast<RealScalar>(-1);
784   for(Index j = 0; j < cols(); ++j)
785   {
786     Index maxi = (std::min)(j, rows()-1);
787     for(Index i = 0; i <= maxi; ++i)
788     {
789       RealScalar absValue = internal::abs(coeff(i,j));
790       if(absValue > maxAbsOnUpperPart) maxAbsOnUpperPart = absValue;
791     }
792   }
793   RealScalar threshold = maxAbsOnUpperPart * prec;
794   for(Index j = 0; j < cols(); ++j)
795     for(Index i = j+1; i < rows(); ++i)
796       if(internal::abs(coeff(i, j)) > threshold) return false;
797   return true;
798 }
799 
800 /** \returns true if *this is approximately equal to a lower triangular matrix,
801   *          within the precision given by \a prec.
802   *
803   * \sa isUpperTriangular()
804   */
805 template<typename Derived>
806 bool MatrixBase<Derived>::isLowerTriangular(RealScalar prec) const
807 {
808   RealScalar maxAbsOnLowerPart = static_cast<RealScalar>(-1);
809   for(Index j = 0; j < cols(); ++j)
810     for(Index i = j; i < rows(); ++i)
811     {
812       RealScalar absValue = internal::abs(coeff(i,j));
813       if(absValue > maxAbsOnLowerPart) maxAbsOnLowerPart = absValue;
814     }
815   RealScalar threshold = maxAbsOnLowerPart * prec;
816   for(Index j = 1; j < cols(); ++j)
817   {
818     Index maxi = (std::min)(j, rows()-1);
819     for(Index i = 0; i < maxi; ++i)
820       if(internal::abs(coeff(i, j)) > threshold) return false;
821   }
822   return true;
823 }
824 
825 } // end namespace Eigen
826 
827 #endif // EIGEN_TRIANGULARMATRIX_H
828