DTLZ1.h
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1 //===========================================================================
2 /*!
3  *
4  *
5  * \brief Objective function DTLZ1
6  *
7  *
8  *
9  * \author T.Voss, T. Glasmachers, O.Krause
10  * \date 2010-2011
11  *
12  *
13  * \par Copyright 1995-2017 Shark Development Team
14  *
15  * <BR><HR>
16  * This file is part of Shark.
17  * <http://shark-ml.org/>
18  *
19  * Shark is free software: you can redistribute it and/or modify
20  * it under the terms of the GNU Lesser General Public License as published
21  * by the Free Software Foundation, either version 3 of the License, or
22  * (at your option) any later version.
23  *
24  * Shark is distributed in the hope that it will be useful,
25  * but WITHOUT ANY WARRANTY; without even the implied warranty of
26  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
27  * GNU Lesser General Public License for more details.
28  *
29  * You should have received a copy of the GNU Lesser General Public License
30  * along with Shark. If not, see <http://www.gnu.org/licenses/>.
31  *
32  */
33 //===========================================================================
34 #ifndef SHARK_OBJECTIVEFUNCTIONS_BENCHMARK_DTLZ1_H
35 #define SHARK_OBJECTIVEFUNCTIONS_BENCHMARK_DTLZ1_H
36 
37 #include <shark/ObjectiveFunctions/AbstractObjectiveFunction.h>
38 #include <shark/ObjectiveFunctions/BoxConstraintHandler.h>
39 
40 namespace shark {
41 
42 /**
43 * \brief Implements the benchmark function DTLZ1.
44 *
45 * See: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.18.7531&rep=rep1&type=pdf
46 * The benchmark function exposes the following features:
47 * - Scalable w.r.t. the searchspace and w.r.t. the objective space.
48 * - Highly multi-modal.
49 */
50 struct DTLZ1 : public MultiObjectiveFunction
51 {
52  DTLZ1(std::size_t numVariables = 0) : m_objectives(2), m_handler(numVariables,0,1 ){
53  announceConstraintHandler(&m_handler);
54  }
55 
56  /// \brief From INameable: return the class name.
57  std::string name() const
58  { return "DTLZ1"; }
59 
60  std::size_t numberOfObjectives()const{
61  return m_objectives;
62  }
63  bool hasScalableObjectives()const{
64  return true;
65  }
66 
67  void setNumberOfObjectives( std::size_t numberOfObjectives ){
68  m_objectives = numberOfObjectives;
69  }
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  void setNumberOfVariables( std::size_t numberOfVariables ){
81  m_handler.setBounds(
82  SearchPointType(numberOfVariables,0),
83  SearchPointType(numberOfVariables,1)
84  );
85  }
86 
87  ResultType eval( const SearchPointType & x ) const {
88  m_evaluationCounter++;
89 
90  ResultType value( numberOfObjectives() );
91 
92  std::size_t k = numberOfVariables() - numberOfObjectives()+1;
93  double g = (double)k;
94  for( std::size_t i = numberOfVariables() - k; i < numberOfVariables(); i++ )
95  g += sqr( x( i ) - 0.5 ) - std::cos( 20.0 * M_PI * ( x( i ) - 0.5) );
96  g *= 100;
97 
98  for (std::size_t i = 0; i < numberOfObjectives(); i++) {
99  value[i] = 0.5*(1.0 + g);
100  for( std::size_t j = 0; j < numberOfObjectives() - i -1; ++j)
101  value[i] *= x( j );
102 
103  if (i > 0)
104  value[i] *= 1 - x( numberOfObjectives() - i -1);
105  }
106 
107  return value;
108  }
109 private:
110  std::size_t m_objectives;
111  BoxConstraintHandler<SearchPointType> m_handler;
112 
113 };
114 
115 }
116 
117 #endif