1  #region License Information


2  /* HeuristicLab


3  * Copyright (C) 20022013 Heuristic and Evolutionary Algorithms Laboratory (HEAL)


4  *


5  * This file is part of HeuristicLab.


6  *


7  * HeuristicLab is free software: you can redistribute it and/or modify


8  * it under the terms of the GNU General Public License as published by


9  * the Free Software Foundation, either version 3 of the License, or


10  * (at your option) any later version.


11  *


12  * HeuristicLab is distributed in the hope that it will be useful,


13  * but WITHOUT ANY WARRANTY; without even the implied warranty of


14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the


15  * GNU General Public License for more details.


16  *


17  * You should have received a copy of the GNU General Public License


18  * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.


19  */


20  #endregion


21 


22  using System;


23  using HeuristicLab.Common;


24  using HeuristicLab.Core;


25  using HeuristicLab.Data;


26  using HeuristicLab.Encodings.RealVectorEncoding;


27  using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;


28 


29  namespace HeuristicLab.Problems.TestFunctions {


30  /// <summary>


31  /// The Levy function is implemented as described on http://wwwoptima.amp.i.kyotou.ac.jp/member/student/hedar/Hedar_files/TestGO_files/Page2056.htm, last accessed April 12th, 2010.


32  /// </summary>


33  [Item("LevyEvaluator", "Evaluates the Levy function on a given point. The optimum of this function is 0 at (1,1,...,1). It is implemented as described on http://wwwoptima.amp.i.kyotou.ac.jp/member/student/hedar/Hedar_files/TestGO_files/Page2056.htm, last accessed April 12th, 2010.")]


34  [StorableClass]


35  public class LevyEvaluator : SingleObjectiveTestFunctionProblemEvaluator {


36  public override string FunctionName { get { return "Levy"; } }


37  /// <summary>


38  /// Returns false as the Levy function is a minimization problem.


39  /// </summary>


40  public override bool Maximization {


41  get { return false; }


42  }


43  /// <summary>


44  /// Gets the optimum function value (0).


45  /// </summary>


46  public override double BestKnownQuality {


47  get { return 0; }


48  }


49  /// <summary>


50  /// Gets the lower and upper bound of the function.


51  /// </summary>


52  public override DoubleMatrix Bounds {


53  get { return new DoubleMatrix(new double[,] { { 10, 10 } }); }


54  }


55  /// <summary>


56  /// Gets the minimum problem size (2).


57  /// </summary>


58  public override int MinimumProblemSize {


59  get { return 2; }


60  }


61  /// <summary>


62  /// Gets the (theoretical) maximum problem size (2^31  1).


63  /// </summary>


64  public override int MaximumProblemSize {


65  get { return int.MaxValue; }


66  }


67 


68  [StorableConstructor]


69  protected LevyEvaluator(bool deserializing) : base(deserializing) { }


70  protected LevyEvaluator(LevyEvaluator original, Cloner cloner) : base(original, cloner) { }


71  public LevyEvaluator() : base() { }


72 


73  public override IDeepCloneable Clone(Cloner cloner) {


74  return new LevyEvaluator(this, cloner);


75  }


76 


77  public override RealVector GetBestKnownSolution(int dimension) {


78  if (dimension < 2) throw new ArgumentException(Name + ": This function is not defined for 1 dimension.");


79  RealVector result = new RealVector(dimension);


80  for (int i = 0; i < dimension; i++) result[i] = 1;


81  return result;


82  }


83  /// <summary>


84  /// Evaluates the test function for a specific <paramref name="point"/>.


85  /// </summary>


86  /// <param name="point">Ndimensional point for which the test function should be evaluated.</param>


87  /// <returns>The result value of the Levy function at the given point.</returns>


88  public static double Apply(RealVector point) {


89  int length = point.Length;


90  double[] z = new double[length];


91  double s;


92 


93  for (int i = 0; i < length; i++) {


94  z[i] = 1 + (point[i]  1) / 4;


95  }


96 


97  s = Math.Sin(Math.PI * z[0]);


98  if (Math.Abs(s) < 1e15) s = 0; // Math.Sin(Math.PI) == 0.00000000000000012246063538223773


99  s *= s;


100 


101  for (int i = 0; i < length  1; i++) {


102  s += (z[i]  1) * (z[i]  1) * (1 + 10 * Math.Pow(Math.Sin(Math.PI * z[i] + 1), 2));


103  }


104 


105  return s + Math.Pow(z[length  1]  1, 2) * (1 + Math.Pow(Math.Sin(2 * Math.PI * z[length  1]), 2));


106  }


107 


108  /// <summary>


109  /// Evaluates the test function for a specific <paramref name="point"/>.


110  /// </summary>


111  /// <remarks>Calls <see cref="Apply"/>.</remarks>


112  /// <param name="point">Ndimensional point for which the test function should be evaluated.</param>


113  /// <returns>The result value of the Levy function at the given point.</returns>


114  public override double Evaluate(RealVector point) {


115  return Apply(point);


116  }


117  }


118  }

