LZ7.h
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1 //===========================================================================
2 /*!
3  *
4  *
5  * \brief Multi-objective optimization benchmark function LZ7.
6  *
7  * The function is described in
8  *
9  * H. Li and Q. Zhang.
10  * Multiobjective Optimization Problems with Complicated Pareto Sets, MOEA/D and NSGA-II,
11  * IEEE Trans on Evolutionary Computation, 2(12):284-302, April 2009.
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 #ifndef SHARK_OBJECTIVEFUNCTIONS_BENCHMARK_LZ7_H
41 #define SHARK_OBJECTIVEFUNCTIONS_BENCHMARK_LZ7_H
42 
45 
46 namespace shark {
47 /*! \brief Multi-objective optimization benchmark function LZ7.
48 *
49 * The function is described in
50 *
51 * H. Li and Q. Zhang.
52 * Multiobjective Optimization Problems with Complicated Pareto Sets, MOEA/D and NSGA-II,
53 * IEEE Trans on Evolutionary Computation, 2(12):284-302, April 2009.
54 */
55 struct LZ7 : public MultiObjectiveFunction
56 {
57  LZ7(std::size_t numVariables = 0) : m_handler(SearchPointType(numVariables,0),SearchPointType(numVariables,1) ){
58  announceConstraintHandler(&m_handler);
59  }
60 
61  /// \brief From INameable: return the class name.
62  std::string name() const
63  { return "LZ7"; }
64 
65  std::size_t numberOfObjectives()const{
66  return 2;
67  }
68 
69  std::size_t numberOfVariables()const{
70  return m_handler.dimensions();
71  }
72 
74  return true;
75  }
76 
77  /// \brief Adjusts the number of variables if the function is scalable.
78  /// \param [in] numberOfVariables The new dimension.
80  m_handler.setBounds(
81  SearchPointType(numberOfVariables,0),
82  SearchPointType(numberOfVariables,1)
83  );
84  }
85 
86  ResultType eval( const SearchPointType & x ) const {
88 
89  ResultType value( 2, 0 );
90 
91  std::size_t counter1 = 0, counter2 = 0;
92  for( std::size_t i = 1; i < x.size(); i++ ) {
93  double y = x(i) - ::pow( x(0), 0.5*(1.0 + 3*(i-1)/(x.size()-1) ) );
94  if( i % 2 == 0 ) {
95  counter2++;
96  value[1] += 4*sqr( y ) - ::cos( 8*y*M_PI) + 1.;
97  } else {
98  counter1++;
99  value[0] += 4*sqr( y ) - ::cos( 8*y*M_PI) + 1.;
100  }
101  }
102 
103  value[0] *= 2./counter1;
104  value[0] += x( 0 );
105 
106  value[1] *= 2./counter2;
107  value[1] += 1 - std::sqrt( x( 0 ) );
108 
109  return value;
110  }
111 private:
113 };
114 }
115 #endif