[3150] | 1 | #region License Information
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| 2 | /* HeuristicLab
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[11171] | 3 | * Copyright (C) 2002-2014 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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[3150] | 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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[4722] | 23 | using HeuristicLab.Common;
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[3150] | 24 | using HeuristicLab.Core;
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| 25 | using HeuristicLab.Data;
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[3154] | 26 | using HeuristicLab.Encodings.RealVectorEncoding;
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[4068] | 27 | using HeuristicLab.Parameters;
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[3154] | 28 | using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
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[3150] | 29 |
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[3170] | 30 | namespace HeuristicLab.Problems.TestFunctions {
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[3150] | 31 | /// <summary>
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[3315] | 32 | /// The sphere function is a unimodal function that has its optimum at the origin.
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| 33 | /// It is implemented as described in Beyer, H.-G. and Schwefel, H.-P. 2002. Evolution Strategies - A Comprehensive Introduction Natural Computing, 1, pp. 3-52.
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[3150] | 34 | /// </summary>
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[3315] | 35 | [Item("SphereEvaluator", "Evaluates the Sphere function y = C * ||X||^Alpha on a given point. The optimum of this function is 0 at the origin. It is implemented as described in Beyer, H.-G. and Schwefel, H.-P. 2002. Evolution Strategies - A Comprehensive Introduction Natural Computing, 1, pp. 3-52.")]
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[3154] | 36 | [StorableClass]
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[3170] | 37 | public class SphereEvaluator : SingleObjectiveTestFunctionProblemEvaluator {
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[9980] | 38 | public override string FunctionName { get { return "Sphere"; } }
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[3154] | 39 | /// <summary>
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[3315] | 40 | /// Returns false as the Sphere function is a minimization problem.
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[3154] | 41 | /// </summary>
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| 42 | public override bool Maximization {
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| 43 | get { return false; }
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[3150] | 44 | }
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[3154] | 45 | /// <summary>
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| 46 | /// Gets the optimum function value (0).
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| 47 | /// </summary>
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| 48 | public override double BestKnownQuality {
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| 49 | get { return 0; }
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| 50 | }
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| 51 | /// <summary>
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| 52 | /// Gets the lower and upper bound of the function.
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| 53 | /// </summary>
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| 54 | public override DoubleMatrix Bounds {
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| 55 | get { return new DoubleMatrix(new double[,] { { -5.12, 5.12 } }); }
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| 56 | }
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| 57 | /// <summary>
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| 58 | /// Gets the minimum problem size (1).
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| 59 | /// </summary>
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| 60 | public override int MinimumProblemSize {
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| 61 | get { return 1; }
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| 62 | }
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| 63 | /// <summary>
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| 64 | /// Gets the (theoretical) maximum problem size (2^31 - 1).
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| 65 | /// </summary>
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| 66 | public override int MaximumProblemSize {
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| 67 | get { return int.MaxValue; }
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| 68 | }
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[3781] | 69 |
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[4722] | 70 | public override IDeepCloneable Clone(Cloner cloner) {
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| 71 | return new SphereEvaluator(this, cloner);
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| 72 | }
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| 73 |
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[3781] | 74 | public override RealVector GetBestKnownSolution(int dimension) {
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| 75 | return new RealVector(dimension);
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| 76 | }
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| 77 |
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[3315] | 78 | /// <summary>
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| 79 | /// The parameter C modifies the steepness of the objective function y = C * ||X||^Alpha. Default is C = 1.
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| 80 | /// </summary>
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| 81 | public ValueParameter<DoubleValue> CParameter {
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| 82 | get { return (ValueParameter<DoubleValue>)Parameters["C"]; }
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| 83 | }
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| 84 | /// <summary>
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| 85 | /// The parameter Alpha modifies the steepness of the objective function y = C * ||X||^Alpha. Default is Alpha = 2.
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| 86 | /// </summary>
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| 87 | public ValueParameter<DoubleValue> AlphaParameter {
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| 88 | get { return (ValueParameter<DoubleValue>)Parameters["Alpha"]; }
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| 89 | }
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| 90 | /// <summary>
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| 91 | /// The parameter C modifies the steepness of the objective function y = C * ||X||^Alpha. Default is C = 1.
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| 92 | /// </summary>
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| 93 | public DoubleValue C {
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| 94 | get { return CParameter.Value; }
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| 95 | set { if (value != null) CParameter.Value = value; }
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| 96 | }
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| 97 | /// <summary>
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| 98 | /// The parameter Alpha modifies the steepness of the objective function y = C * ||X||^Alpha. Default is Alpha = 2.
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| 99 | /// </summary>
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| 100 | public DoubleValue Alpha {
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| 101 | get { return AlphaParameter.Value; }
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| 102 | set { if (value != null) AlphaParameter.Value = value; }
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| 103 | }
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[3150] | 104 |
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[4722] | 105 | [StorableConstructor]
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| 106 | protected SphereEvaluator(bool deserializing) : base(deserializing) { }
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| 107 | protected SphereEvaluator(SphereEvaluator original, Cloner cloner) : base(original, cloner) { }
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[3150] | 108 | /// <summary>
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[3315] | 109 | /// Initializes a new instance of the SphereEvaluator with two parameters (<c>C</c> and <c>Alpha</c>).
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| 110 | /// </summary>
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| 111 | public SphereEvaluator()
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| 112 | : base() {
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| 113 | Parameters.Add(new ValueParameter<DoubleValue>("C", "The parameter C modifies the steepness of the objective function y = C * ||X||^Alpha. Default is C = 1.", new DoubleValue(1)));
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| 114 | Parameters.Add(new ValueParameter<DoubleValue>("Alpha", "The parameter Alpha modifies the steepness of the objective function y = C * ||X||^Alpha. Default is Alpha = 2.", new DoubleValue(2)));
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| 115 | }
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| 116 | /// <summary>
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[3150] | 117 | /// Evaluates the test function for a specific <paramref name="point"/>.
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| 118 | /// </summary>
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| 119 | /// <param name="point">N-dimensional point for which the test function should be evaluated.</param>
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| 120 | /// <returns>The result value of the Sphere function at the given point.</returns>
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[3315] | 121 | public static double Apply(RealVector point, double c, double alpha) {
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[3150] | 122 | double result = 0;
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| 123 | for (int i = 0; i < point.Length; i++)
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| 124 | result += point[i] * point[i];
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[3315] | 125 | if (alpha != 2) result = Math.Pow(Math.Sqrt(result), alpha);
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| 126 | return c * result;
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[3150] | 127 | }
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| 128 |
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| 129 | /// <summary>
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| 130 | /// Evaluates the test function for a specific <paramref name="point"/>.
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| 131 | /// </summary>
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| 132 | /// <remarks>Calls <see cref="Apply"/>.</remarks>
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| 133 | /// <param name="point">N-dimensional point for which the test function should be evaluated.</param>
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| 134 | /// <returns>The result value of the Sphere function at the given point.</returns>
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[9407] | 135 | public override double Evaluate(RealVector point) {
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[3315] | 136 | return Apply(point, C.Value, Alpha.Value);
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[3150] | 137 | }
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| 138 | }
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| 139 | }
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