1 | #region License Information
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2 | /* HeuristicLab
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3 | * Copyright (C) 2002-2010 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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4 | *
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5 | * This file is part of HeuristicLab.
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6 | *
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7 | * HeuristicLab is free software: you can redistribute it and/or modify
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8 | * it under the terms of the GNU General Public License as published by
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9 | * the Free Software Foundation, either version 3 of the License, or
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10 | * (at your option) any later version.
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11 | *
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12 | * HeuristicLab is distributed in the hope that it will be useful,
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13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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15 | * GNU General Public License for more details.
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16 | *
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17 | * You should have received a copy of the GNU General Public License
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18 | * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
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19 | */
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20 | #endregion
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21 |
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22 | using System;
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23 | using HeuristicLab.Core;
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24 | using HeuristicLab.Data;
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25 | using HeuristicLab.Encodings.RealVectorEncoding;
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26 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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27 |
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28 | namespace HeuristicLab.Problems.TestFunctions {
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29 | /// <summary>
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30 | /// The Schwefel function (sine root) is implemented as described in Affenzeller, M. and Wagner, S. 2005. Offspring Selection: A New Self-Adaptive Selection Scheme for Genetic Algorithms. Ribeiro, B., Albrecht, R. F., Dobnikar, A., Pearson, D. W., and Steele, N. C. (eds.). Adaptive and Natural Computing Algorithms, pp. 218-221, Springer.
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31 | /// </summary>
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32 | [Item("SchwefelEvaluator", "Evaluates the Schwefel function (sine root) on a given point. In the given bounds [-500;500] the optimum of this function is close to 0 at (420.968746453712,420.968746453712,...,420.968746453712). It is implemented as described in Affenzeller, M. and Wagner, S. 2005. Offspring Selection: A New Self-Adaptive Selection Scheme for Genetic Algorithms. Ribeiro, B., Albrecht, R. F., Dobnikar, A., Pearson, D. W., and Steele, N. C. (eds.). Adaptive and Natural Computing Algorithms, pp. 218-221, Springer.")]
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33 | [StorableClass]
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34 | public class SchwefelEvaluator : SingleObjectiveTestFunctionProblemEvaluator {
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35 | /// <summary>
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36 | /// Returns false as the Schwefel (sine root) function is a minimization problem.
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37 | /// </summary>
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38 | public override bool Maximization {
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39 | get { return false; }
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40 | }
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41 | /// <summary>
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42 | /// Gets the optimum function value (0).
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43 | /// </summary>
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44 | public override double BestKnownQuality {
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45 | get { return 0; }
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46 | }
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47 | /// <summary>
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48 | /// Gets the lower and upper bound of the function.
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49 | /// </summary>
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50 | public override DoubleMatrix Bounds {
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51 | get { return new DoubleMatrix(new double[,] { { -500, 500 } }); }
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52 | }
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53 | /// <summary>
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54 | /// Gets the minimum problem size (1).
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55 | /// </summary>
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56 | public override int MinimumProblemSize {
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57 | get { return 1; }
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58 | }
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59 | /// <summary>
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60 | /// Gets the (theoretical) maximum problem size (2^31 - 1).
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61 | /// </summary>
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62 | public override int MaximumProblemSize {
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63 | get { return int.MaxValue; }
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64 | }
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65 |
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66 | public override RealVector GetBestKnownSolution(int dimension) {
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67 | return null;
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68 | }
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69 |
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70 | /// <summary>
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71 | /// Evaluates the test function for a specific <paramref name="point"/>.
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72 | /// </summary>
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73 | /// <param name="point">N-dimensional point for which the test function should be evaluated.</param>
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74 | /// <returns>The result value of the Schwefel function at the given point.</returns>
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75 | public static double Apply(RealVector point) {
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76 | double result = 418.982887272433 * point.Length;
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77 | for (int i = 0; i < point.Length; i++)
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78 | result -= point[i] * Math.Sin(Math.Sqrt(Math.Abs(point[i])));
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79 | return (result);
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80 | }
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81 |
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82 | /// <summary>
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83 | /// Evaluates the test function for a specific <paramref name="point"/>.
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84 | /// </summary>
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85 | /// <remarks>Calls <see cref="Apply"/>.</remarks>
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86 | /// <param name="point">N-dimensional point for which the test function should be evaluated.</param>
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87 | /// <returns>The result value of the Schwefel function at the given point.</returns>
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88 | protected override double EvaluateFunction(RealVector point) {
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89 | return Apply(point);
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90 | }
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91 | }
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92 | }
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