Schwefel.h
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1 /*!
2  *
3  *
4  * \brief Convex benchmark function.
5  *
6  *
7  * \author T. Voss
8  * \date 2010-2011
9  *
10  *
11  * \par Copyright 1995-2017 Shark Development Team
12  *
13  * <BR><HR>
14  * This file is part of Shark.
15  * <http://shark-ml.org/>
16  *
17  * Shark is free software: you can redistribute it and/or modify
18  * it under the terms of the GNU Lesser General Public License as published
19  * by the Free Software Foundation, either version 3 of the License, or
20  * (at your option) any later version.
21  *
22  * Shark is distributed in the hope that it will be useful,
23  * but WITHOUT ANY WARRANTY; without even the implied warranty of
24  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
25  * GNU Lesser General Public License for more details.
26  *
27  * You should have received a copy of the GNU Lesser General Public License
28  * along with Shark. If not, see <http://www.gnu.org/licenses/>.
29  *
30  */
31 #ifndef SHARK_OBJECTIVEFUNCTIONS_BENCHMARK_SCHWEFEL_H
32 #define SHARK_OBJECTIVEFUNCTIONS_BENCHMARK_SCHWEFEL_H
33 
35 #include <shark/Core/Random.h>
36 
37 namespace shark {
38 /**
39  * \brief Convex benchmark function.
40  */
42 
43  Schwefel(std::size_t numberOfVariables = 5):m_numberOfVariables(numberOfVariables) {
45  }
46 
47  /// \brief From INameable: return the class name.
48  std::string name() const
49  { return "Schwefel"; }
50 
51  std::size_t numberOfVariables()const{
52  return m_numberOfVariables;
53  }
54 
56  return true;
57  }
58 
60  m_numberOfVariables = numberOfVariables;
61  }
62 
64  RealVector x(numberOfVariables());
65 
66  for (std::size_t i = 0; i < x.size(); i++) {
67  x(i) = random::gauss(*mep_rng, 0,1);
68  }
69  return x;
70  }
71 
72  double eval(const SearchPointType &p) const {
74  double value = 0;
75  double sum= 0;
76  for(std::size_t i = 0; i != m_numberOfVariables; ++i){
77  sum+= p(i);
78  value+=sqr(sum);
79  }
80  return value;
81  }
82 private:
83  std::size_t m_numberOfVariables;
84 };
85 
86 }
87 
88 #endif