Line data Source code
1 : // The libMesh Finite Element Library.
2 : // Copyright (C) 2002-2025 Benjamin S. Kirk, John W. Peterson, Roy H. Stogner
3 :
4 : // This library is free software; you can redistribute it and/or
5 : // modify it under the terms of the GNU Lesser General Public
6 : // License as published by the Free Software Foundation; either
7 : // version 2.1 of the License, or (at your option) any later version.
8 :
9 : // This library is distributed in the hope that it will be useful,
10 : // but WITHOUT ANY WARRANTY; without even the implied warranty of
11 : // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 : // Lesser General Public License for more details.
13 :
14 : // You should have received a copy of the GNU Lesser General Public
15 : // License along with this library; if not, write to the Free Software
16 : // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
17 :
18 :
19 :
20 : #ifndef LIBMESH_FEM_FUNCTION_BASE_H
21 : #define LIBMESH_FEM_FUNCTION_BASE_H
22 :
23 : // Local Includes
24 : #include "libmesh/libmesh_common.h"
25 : #include "libmesh/dense_vector.h" // required to instantiate a DenseVector<> below
26 : #include "libmesh/fem_context.h"
27 :
28 : // C++ includes
29 : #include <memory>
30 :
31 : namespace libMesh
32 : {
33 :
34 : // Forward Declarations
35 : class Point;
36 :
37 : /**
38 : * FEMFunctionBase is a base class from which users can derive in
39 : * order to define "function-like" objects that can be used within
40 : * FEMSystem.
41 : *
42 : * \author Roy Stogner
43 : * \date 2012
44 : */
45 : template <typename Output=Number>
46 : class FEMFunctionBase
47 : {
48 : protected:
49 :
50 : /**
51 : * Constructor.
52 : */
53 12818 : FEMFunctionBase () = default;
54 :
55 : public:
56 :
57 : /**
58 : * The 5 special functions can be defaulted for this class.
59 : */
60 : FEMFunctionBase (FEMFunctionBase &&) = default;
61 : FEMFunctionBase (const FEMFunctionBase &) = default;
62 : FEMFunctionBase & operator= (const FEMFunctionBase &) = default;
63 : FEMFunctionBase & operator= (FEMFunctionBase &&) = default;
64 12818 : virtual ~FEMFunctionBase () = default;
65 :
66 : /**
67 : * Any post-construction initialization
68 : */
69 0 : virtual void init () {}
70 :
71 : /**
72 : * Prepares a context object for use.
73 : *
74 : * Most problems will want to reimplement this for efficiency, in
75 : * order to call FE::get_*() as their particular function requires.
76 : */
77 14008 : virtual void init_context (const FEMContext &) {}
78 :
79 : /**
80 : * \returns A new copy of the function.
81 : *
82 : * The new copy should be as "deep" as necessary to allow
83 : * independent destruction and simultaneous evaluations of the
84 : * copies in different threads.
85 : */
86 : virtual std::unique_ptr<FEMFunctionBase<Output>> clone () const = 0;
87 :
88 : /**
89 : * \returns The scalar function value at coordinate \p p and time \p
90 : * time, which defaults to zero.
91 : *
92 : * Pure virtual, so you have to override it.
93 : */
94 : virtual Output operator() (const FEMContext &,
95 : const Point & p,
96 : const Real time = 0.) = 0;
97 :
98 : /**
99 : * Evaluation function for time-independent vector-valued functions.
100 : * Sets output values in the passed-in \p output DenseVector.
101 : */
102 : void operator() (const FEMContext &,
103 : const Point & p,
104 : DenseVector<Output> & output);
105 :
106 : /**
107 : * Evaluation function for time-dependent vector-valued functions.
108 : * Sets output values in the passed-in \p output DenseVector.
109 : *
110 : * Pure virtual, so you have to override it.
111 : */
112 : virtual void operator() (const FEMContext &,
113 : const Point & p,
114 : const Real time,
115 : DenseVector<Output> & output) = 0;
116 :
117 : /**
118 : * \returns The vector component \p i at coordinate \p p and time \p
119 : * time.
120 : *
121 : * \note Subclasses aren't required to override this, since the default
122 : * implementation is based on the full vector evaluation, which is
123 : * often correct.
124 : *
125 : * \note Subclasses are recommended to override this, since the default
126 : * implementation is based on a vector evaluation, which is usually
127 : * unnecessarily inefficient.
128 : */
129 : virtual Output component(const FEMContext &,
130 : unsigned int i,
131 : const Point & p,
132 : Real time=0.);
133 : };
134 :
135 : template <typename Output>
136 : inline
137 0 : Output FEMFunctionBase<Output>::component (const FEMContext & context,
138 : unsigned int i,
139 : const Point & p,
140 : Real time)
141 : {
142 0 : DenseVector<Output> outvec(i+1);
143 0 : (*this)(context, p, time, outvec);
144 0 : return outvec(i);
145 : }
146 :
147 : template <typename Output>
148 : inline
149 : void FEMFunctionBase<Output>::operator() (const FEMContext & context,
150 : const Point & p,
151 : DenseVector<Output> & output)
152 : {
153 : // Call the time-dependent function with t=0.
154 : this->operator()(context, p, 0., output);
155 : }
156 :
157 : } // namespace libMesh
158 :
159 : #endif // LIBMESH_FEM_FUNCTION_BASE_H
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