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Sacado_ELRFad_Expression.hpp
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1// @HEADER
2// ***********************************************************************
3//
4// Sacado Package
5// Copyright (2006) Sandia Corporation
6//
7// Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
8// the U.S. Government retains certain rights in this software.
9//
10// This library is free software; you can redistribute it and/or modify
11// it under the terms of the GNU Lesser General Public License as
12// published by the Free Software Foundation; either version 2.1 of the
13// License, or (at your option) any later version.
14//
15// This library is distributed in the hope that it will be useful, but
16// WITHOUT ANY WARRANTY; without even the implied warranty of
17// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18// Lesser General Public License for more details.
19//
20// You should have received a copy of the GNU Lesser General Public
21// License along with this library; if not, write to the Free Software
22// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
23// USA
24// Questions? Contact David M. Gay (dmgay@sandia.gov) or Eric T. Phipps
25// (etphipp@sandia.gov).
26//
27// ***********************************************************************
28//
29// The forward-mode AD classes in Sacado are a derivative work of the
30// expression template classes in the Fad package by Nicolas Di Cesare.
31// The following banner is included in the original Fad source code:
32//
33// ************ DO NOT REMOVE THIS BANNER ****************
34//
35// Nicolas Di Cesare <Nicolas.Dicesare@ann.jussieu.fr>
36// http://www.ann.jussieu.fr/~dicesare
37//
38// CEMRACS 98 : C++ courses,
39// templates : new C++ techniques
40// for scientific computing
41//
42//********************************************************
43//
44// A short implementation ( not all operators and
45// functions are overloaded ) of 1st order Automatic
46// Differentiation in forward mode (FAD) using
47// EXPRESSION TEMPLATES.
48//
49//********************************************************
50// @HEADER
51
52#ifndef SACADO_ELRFAD_EXPRESSION_HPP
53#define SACADO_ELRFAD_EXPRESSION_HPP
54
55#include "Sacado_Traits.hpp"
56
57namespace Sacado {
58
59 namespace ELRFad {
60
62
69 template <typename> struct BaseExpr {};
70
72
76 template <typename ExprT>
77 class Expr {};
78
80
85 template <typename T>
86 struct ExprLevel {
87 static const unsigned value = 0;
88 };
89
90 template <typename T>
91 struct ExprLevel< Expr<T> > {
92 static const unsigned value =
94 };
95
97 template <typename T>
98 struct IsFadExpr {
99 static const bool value = false;
100 };
101
102 template <typename T>
103 struct IsFadExpr< Expr<T> > {
104 static const bool value = true;
105 };
106
108
111 template <typename ConstT>
112 class ConstExpr {
113
114 public:
115
117 typedef ConstT value_type;
118
121
123 typedef ConstT base_expr_type;
124
126 static const int num_args = 0;
127
130 ConstExpr(const ConstT& constant) : constant_(constant) {}
131
134 int size() const { return 0; }
135
138 bool updateValue() const { return true; }
139
142 value_type val() const { return constant_; }
143
147 value_type partials[]) const {}
148
151 void getTangents(int i, value_type dots[]) const {}
152
154 template <int Arg>
156 value_type getTangent(int i) const { return 0.0; }
157
159 template <int Arg>
161 bool isActive() const { return false; }
162
165 bool isLinear() const { return true; }
166
167 protected:
168
170 const ConstT& constant_;
171
172 }; // class ConstExpr
173
174 template <typename T> struct ExprConstRef {
175 typedef const T& type;
176 };
177 template <typename T> struct ExprConstRef< ConstExpr<T> > {
178 typedef const ConstExpr<T> type;
179 };
180
181 } // namespace ELRFad
182
183 template <typename T>
184 struct IsExpr< ELRFad::Expr<T> > {
185 static const bool value = true;
186 };
187
188 template <typename T>
189 struct BaseExprType< ELRFad::Expr<T> > {
191 };
192
193} // namespace Sacado
194
196
197#endif // SACADO_ELRFAD_EXPRESSION_HPP
#define SACADO_INLINE_FUNCTION
Constant expression template.
const ConstT & constant_
The constant.
SACADO_INLINE_FUNCTION bool isActive() const
Return whether argument is active.
SACADO_INLINE_FUNCTION void computePartials(const value_type &bar, value_type partials[]) const
Return partials w.r.t. arguments.
SACADO_INLINE_FUNCTION void getTangents(int i, value_type dots[]) const
Rturn tangent component i of arguments.
SACADO_INLINE_FUNCTION value_type val() const
Return value of operation.
ConstT value_type
Typename of argument values.
SACADO_INLINE_FUNCTION value_type getTangent(int i) const
Return tangent component i of argument Arg.
ConstT base_expr_type
Typename of base-expressions.
SACADO_INLINE_FUNCTION bool isLinear() const
Return whether expression is linear.
SACADO_INLINE_FUNCTION ConstExpr(const ConstT &constant)
Constructor.
ScalarType< value_type >::type scalar_type
Typename of scalar's (which may be different from ConstT)
static const int num_args
Number of arguments.
SACADO_INLINE_FUNCTION int size() const
Return size of the derivative array of the operation.
SACADO_INLINE_FUNCTION bool updateValue() const
Return whether value should be updated.
Wrapper for a generic expression template.
Get the base Fad type from a view/expression.
Meta-function for determining concrete base expression.
Meta-function for determining nesting with an expression.
Determine whether a given type is an expression.
Is a type an expression.
static const bool value