Inverse.h revision 2b8756b6f1de65d3f8bffab45be6c44ceb7411fc 
1// This file is part of Eigen, a lightweight C++ template library
2// for linear algebra.
3//
4// Copyright (C) 2014 Gael Guennebaud <gael.guennebaud@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_INVERSE_H
11#define EIGEN_INVERSE_H
12
13namespace Eigen {
14
15template<typename XprType,typename StorageKind> class InverseImpl;
16
17namespace internal {
18
19template<typename XprType>
20struct traits<Inverse<XprType> >
21  : traits<typename XprType::PlainObject>
22{
23  typedef typename XprType::PlainObject PlainObject;
24  typedef traits<PlainObject> BaseTraits;
25  enum {
26    Flags = BaseTraits::Flags & RowMajorBit
27  };
28};
29
30} // end namespace internal
31
32/** \class Inverse
33  *
34  * \brief Expression of the inverse of another expression
35  *
36  * \tparam XprType the type of the expression we are taking the inverse
37  *
38  * This class represents an abstract expression of A.inverse()
39  * and most of the time this is the only way it is used.
40  *
41  */
42template<typename XprType>
43class Inverse : public InverseImpl<XprType,typename internal::traits<XprType>::StorageKind>
44{
45public:
46  typedef typename XprType::StorageIndex StorageIndex;
47  typedef typename XprType::PlainObject                       PlainObject;
48  typedef typename XprType::Scalar                            Scalar;
49  typedef typename internal::ref_selector<XprType>::type      XprTypeNested;
50  typedef typename internal::remove_all<XprTypeNested>::type  XprTypeNestedCleaned;
51  typedef typename internal::ref_selector<Inverse>::type Nested;
52  typedef typename internal::remove_all<XprType>::type NestedExpression;
53
54  explicit EIGEN_DEVICE_FUNC Inverse(const XprType &xpr)
55    : m_xpr(xpr)
56  {}
57
58  EIGEN_DEVICE_FUNC Index rows() const { return m_xpr.rows(); }
59  EIGEN_DEVICE_FUNC Index cols() const { return m_xpr.cols(); }
60
61  EIGEN_DEVICE_FUNC const XprTypeNestedCleaned& nestedExpression() const { return m_xpr; }
62
63protected:
64  XprTypeNested m_xpr;
65};
66
67// Generic API dispatcher
68template<typename XprType, typename StorageKind>
69class InverseImpl
70  : public internal::generic_xpr_base<Inverse<XprType> >::type
71{
72public:
73  typedef typename internal::generic_xpr_base<Inverse<XprType> >::type Base;
74  typedef typename XprType::Scalar Scalar;
75private:
76
77  Scalar coeff(Index row, Index col) const;
78  Scalar coeff(Index i) const;
79};
80
81namespace internal {
82
83/** \internal
84  * \brief Default evaluator for Inverse expression.
85  *
86  * This default evaluator for Inverse expression simply evaluate the inverse into a temporary
87  * by a call to internal::call_assignment_no_alias.
88  * Therefore, inverse implementers only have to specialize Assignment<Dst,Inverse<...>, ...> for
89  * there own nested expression.
90  *
91  * \sa class Inverse
92  */
93template<typename ArgType>
94struct unary_evaluator<Inverse<ArgType> >
95  : public evaluator<typename Inverse<ArgType>::PlainObject>
96{
97  typedef Inverse<ArgType> InverseType;
98  typedef typename InverseType::PlainObject PlainObject;
99  typedef evaluator<PlainObject> Base;
100
101  enum { Flags = Base::Flags | EvalBeforeNestingBit };
102
103  unary_evaluator(const InverseType& inv_xpr)
104    : m_result(inv_xpr.rows(), inv_xpr.cols())
105  {
106    ::new (static_cast<Base*>(this)) Base(m_result);
107    internal::call_assignment_no_alias(m_result, inv_xpr);
108  }
109
110protected:
111  PlainObject m_result;
112};
113
114} // end namespace internal
115
116} // end namespace Eigen
117
118#endif // EIGEN_INVERSE_H
119