ZDT1.h
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1 //===========================================================================
2 /*!
3  *
4  *
5  * \brief Multi-objective optimization benchmark function ZDT1
6  *
7  * The function is described in
8  *
9  * Eckart Zitzler, Kalyanmoy Deb, and Lothar Thiele. Comparison of
10  * Multiobjective Evolutionary Algorithms: Empirical
11  * Results. Evolutionary Computation 8(2):173-195, 2000
12  *
13  *
14  *
15  * \author -
16  * \date -
17  *
18  *
19  * \par Copyright 1995-2017 Shark Development Team
20  *
21  * <BR><HR>
22  * This file is part of Shark.
23  * <http://shark-ml.org/>
24  *
25  * Shark is free software: you can redistribute it and/or modify
26  * it under the terms of the GNU Lesser General Public License as published
27  * by the Free Software Foundation, either version 3 of the License, or
28  * (at your option) any later version.
29  *
30  * Shark is distributed in the hope that it will be useful,
31  * but WITHOUT ANY WARRANTY; without even the implied warranty of
32  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
33  * GNU Lesser General Public License for more details.
34  *
35  * You should have received a copy of the GNU Lesser General Public License
36  * along with Shark. If not, see <http://www.gnu.org/licenses/>.
37  *
38  */
39 //===========================================================================
40 
41 
42 #ifndef SHARK_OBJECTIVEFUNCTIONS_BENCHMARK_ZDT1_H
43 #define SHARK_OBJECTIVEFUNCTIONS_BENCHMARK_ZDT1_H
44 
45 #include <shark/ObjectiveFunctions/AbstractObjectiveFunction.h>
46 #include <shark/ObjectiveFunctions/BoxConstraintHandler.h>
47 
48 namespace shark {
49 /*! \brief Multi-objective optimization benchmark function ZDT1
50 *
51 * The function is described in
52 *
53 * Eckart Zitzler, Kalyanmoy Deb, and Lothar Thiele. Comparison of
54 * Multiobjective Evolutionary Algorithms: Empirical
55 * Results. Evolutionary Computation 8(2):173-195, 2000
56 */
57 struct ZDT1 : public MultiObjectiveFunction
58 {
59 
60  ZDT1(std::size_t numVariables = 0) : m_handler(numVariables,0,1) {
61  announceConstraintHandler(&m_handler);
62  }
63 
64  /// \brief From INameable: return the class name.
65  std::string name() const
66  { return "ZDT1"; }
67 
68  std::size_t numberOfObjectives()const{
69  return 2;
70  }
71 
72  std::size_t numberOfVariables()const{
73  return m_handler.dimensions();
74  }
75 
76  bool hasScalableDimensionality()const{
77  return true;
78  }
79 
80  /// \brief Adjusts the number of variables if the function is scalable.
81  /// \param [in] numberOfVariables The new dimension.
82  void setNumberOfVariables( std::size_t numberOfVariables ){
83  m_handler.setBounds(numberOfVariables,0,1);
84  }
85 
86  ResultType eval( const SearchPointType & x ) const {
87  m_evaluationCounter++;
88 
89  ResultType value( 2 );
90 
91  value[0] = x( 0 );
92 
93  double g = 1.0 + 9.0 *(sum(x)-x(0))/(numberOfVariables() - 1.0);
94  double h = 1.0 - std::sqrt(x( 0 ) / g);
95 
96  value[1] = g * h;
97 
98  return value;
99  }
100 
101 private:
102  BoxConstraintHandler<SearchPointType> m_handler;
103 };
104 
105 }
106 #endif