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source: stable/HeuristicLab.Problems.TestFunctions/3.3/Evaluators/SphereEvaluator.cs @ 9990

Last change on this file since 9990 was 9990, checked in by abeham, 9 years ago

#1909: merged into stable branch

File size: 6.0 KB
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1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2013 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
22using System;
23using HeuristicLab.Common;
24using HeuristicLab.Core;
25using HeuristicLab.Data;
26using HeuristicLab.Encodings.RealVectorEncoding;
27using HeuristicLab.Parameters;
28using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
29
30namespace HeuristicLab.Problems.TestFunctions {
31  /// <summary>
32  /// The sphere function is a unimodal function that has its optimum at the origin.
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.
34  /// </summary>
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.")]
36  [StorableClass]
37  public class SphereEvaluator : SingleObjectiveTestFunctionProblemEvaluator {
38    public override string FunctionName { get { return "Sphere"; } }
39    /// <summary>
40    /// Returns false as the Sphere function is a minimization problem.
41    /// </summary>
42    public override bool Maximization {
43      get { return false; }
44    }
45    /// <summary>
46    /// Gets the optimum function value (0).
47    /// </summary>
48    public override double BestKnownQuality {
49      get { return 0; }
50    }
51    /// <summary>
52    /// Gets the lower and upper bound of the function.
53    /// </summary>
54    public override DoubleMatrix Bounds {
55      get { return new DoubleMatrix(new double[,] { { -5.12, 5.12 } }); }
56    }
57    /// <summary>
58    /// Gets the minimum problem size (1).
59    /// </summary>
60    public override int MinimumProblemSize {
61      get { return 1; }
62    }
63    /// <summary>
64    /// Gets the (theoretical) maximum problem size (2^31 - 1).
65    /// </summary>
66    public override int MaximumProblemSize {
67      get { return int.MaxValue; }
68    }
69
70    public override IDeepCloneable Clone(Cloner cloner) {
71      return new SphereEvaluator(this, cloner);
72    }
73
74    public override RealVector GetBestKnownSolution(int dimension) {
75      return new RealVector(dimension);
76    }
77
78    /// <summary>
79    /// The parameter C modifies the steepness of the objective function y = C * ||X||^Alpha. Default is C = 1.
80    /// </summary>
81    public ValueParameter<DoubleValue> CParameter {
82      get { return (ValueParameter<DoubleValue>)Parameters["C"]; }
83    }
84    /// <summary>
85    /// The parameter Alpha modifies the steepness of the objective function y = C * ||X||^Alpha. Default is Alpha = 2.
86    /// </summary>
87    public ValueParameter<DoubleValue> AlphaParameter {
88      get { return (ValueParameter<DoubleValue>)Parameters["Alpha"]; }
89    }
90    /// <summary>
91    /// The parameter C modifies the steepness of the objective function y = C * ||X||^Alpha. Default is C = 1.
92    /// </summary>
93    public DoubleValue C {
94      get { return CParameter.Value; }
95      set { if (value != null) CParameter.Value = value; }
96    }
97    /// <summary>
98    /// The parameter Alpha modifies the steepness of the objective function y = C * ||X||^Alpha. Default is Alpha = 2.
99    /// </summary>
100    public DoubleValue Alpha {
101      get { return AlphaParameter.Value; }
102      set { if (value != null) AlphaParameter.Value = value; }
103    }
104
105    [StorableConstructor]
106    protected SphereEvaluator(bool deserializing) : base(deserializing) { }
107    protected SphereEvaluator(SphereEvaluator original, Cloner cloner) : base(original, cloner) { }
108    /// <summary>
109    /// Initializes a new instance of the SphereEvaluator with two parameters (<c>C</c> and <c>Alpha</c>).
110    /// </summary>
111    public SphereEvaluator()
112      : base() {
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)));
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)));
115    }
116    /// <summary>
117    /// Evaluates the test function for a specific <paramref name="point"/>.
118    /// </summary>
119    /// <param name="point">N-dimensional point for which the test function should be evaluated.</param>
120    /// <returns>The result value of the Sphere function at the given point.</returns>
121    public static double Apply(RealVector point, double c, double alpha) {
122      double result = 0;
123      for (int i = 0; i < point.Length; i++)
124        result += point[i] * point[i];
125      if (alpha != 2) result = Math.Pow(Math.Sqrt(result), alpha);
126      return c * result;
127    }
128
129    /// <summary>
130    /// Evaluates the test function for a specific <paramref name="point"/>.
131    /// </summary>
132    /// <remarks>Calls <see cref="Apply"/>.</remarks>
133    /// <param name="point">N-dimensional point for which the test function should be evaluated.</param>
134    /// <returns>The result value of the Sphere function at the given point.</returns>
135    public override double Evaluate(RealVector point) {
136      return Apply(point, C.Value, Alpha.Value);
137    }
138  }
139}
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