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source: trunk/sources/HeuristicLab.Problems.TestFunctions/3.3/Evaluators/SphereEvaluator.cs @ 5182

Last change on this file since 5182 was 4722, checked in by swagner, 14 years ago

Merged cloning refactoring branch back into trunk (#922)

File size: 5.9 KB
Line 
1#region License Information
2/* HeuristicLab
3 * Copyright (C) 2002-2010 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    /// <summary>
39    /// Returns false as the Sphere function is a minimization problem.
40    /// </summary>
41    public override bool Maximization {
42      get { return false; }
43    }
44    /// <summary>
45    /// Gets the optimum function value (0).
46    /// </summary>
47    public override double BestKnownQuality {
48      get { return 0; }
49    }
50    /// <summary>
51    /// Gets the lower and upper bound of the function.
52    /// </summary>
53    public override DoubleMatrix Bounds {
54      get { return new DoubleMatrix(new double[,] { { -5.12, 5.12 } }); }
55    }
56    /// <summary>
57    /// Gets the minimum problem size (1).
58    /// </summary>
59    public override int MinimumProblemSize {
60      get { return 1; }
61    }
62    /// <summary>
63    /// Gets the (theoretical) maximum problem size (2^31 - 1).
64    /// </summary>
65    public override int MaximumProblemSize {
66      get { return int.MaxValue; }
67    }
68
69    public override IDeepCloneable Clone(Cloner cloner) {
70      return new SphereEvaluator(this, cloner);
71    }
72
73    public override RealVector GetBestKnownSolution(int dimension) {
74      return new RealVector(dimension);
75    }
76
77    /// <summary>
78    /// The parameter C modifies the steepness of the objective function y = C * ||X||^Alpha. Default is C = 1.
79    /// </summary>
80    public ValueParameter<DoubleValue> CParameter {
81      get { return (ValueParameter<DoubleValue>)Parameters["C"]; }
82    }
83    /// <summary>
84    /// The parameter Alpha modifies the steepness of the objective function y = C * ||X||^Alpha. Default is Alpha = 2.
85    /// </summary>
86    public ValueParameter<DoubleValue> AlphaParameter {
87      get { return (ValueParameter<DoubleValue>)Parameters["Alpha"]; }
88    }
89    /// <summary>
90    /// The parameter C modifies the steepness of the objective function y = C * ||X||^Alpha. Default is C = 1.
91    /// </summary>
92    public DoubleValue C {
93      get { return CParameter.Value; }
94      set { if (value != null) CParameter.Value = value; }
95    }
96    /// <summary>
97    /// The parameter Alpha modifies the steepness of the objective function y = C * ||X||^Alpha. Default is Alpha = 2.
98    /// </summary>
99    public DoubleValue Alpha {
100      get { return AlphaParameter.Value; }
101      set { if (value != null) AlphaParameter.Value = value; }
102    }
103
104    [StorableConstructor]
105    protected SphereEvaluator(bool deserializing) : base(deserializing) { }
106    protected SphereEvaluator(SphereEvaluator original, Cloner cloner) : base(original, cloner) { }
107    /// <summary>
108    /// Initializes a new instance of the SphereEvaluator with two parameters (<c>C</c> and <c>Alpha</c>).
109    /// </summary>
110    public SphereEvaluator()
111      : base() {
112      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)));
113      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)));
114    }
115    /// <summary>
116    /// Evaluates the test function for a specific <paramref name="point"/>.
117    /// </summary>
118    /// <param name="point">N-dimensional point for which the test function should be evaluated.</param>
119    /// <returns>The result value of the Sphere function at the given point.</returns>
120    public static double Apply(RealVector point, double c, double alpha) {
121      double result = 0;
122      for (int i = 0; i < point.Length; i++)
123        result += point[i] * point[i];
124      if (alpha != 2) result = Math.Pow(Math.Sqrt(result), alpha);
125      return c * result;
126    }
127
128    /// <summary>
129    /// Evaluates the test function for a specific <paramref name="point"/>.
130    /// </summary>
131    /// <remarks>Calls <see cref="Apply"/>.</remarks>
132    /// <param name="point">N-dimensional point for which the test function should be evaluated.</param>
133    /// <returns>The result value of the Sphere function at the given point.</returns>
134    protected override double EvaluateFunction(RealVector point) {
135      return Apply(point, C.Value, Alpha.Value);
136    }
137  }
138}
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