#region License Information /* HeuristicLab * Copyright (C) 2002-2015 Heuristic and Evolutionary Algorithms Laboratory (HEAL) * * This file is part of HeuristicLab. * * HeuristicLab is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * HeuristicLab is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with HeuristicLab. If not, see . */ #endregion using System; using HeuristicLab.Common; using HeuristicLab.Core; using HeuristicLab.Data; using HeuristicLab.Encodings.RealVectorEncoding; using HeuristicLab.Parameters; using HeuristicLab.Persistence.Default.CompositeSerializers.Storable; namespace HeuristicLab.Problems.TestFunctions { /// /// The sphere function is a unimodal function that has its optimum 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. /// [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.")] [StorableClass("4AD71C5D-6030-4EFC-917E-D052D3FE4724")] public class SphereEvaluator : SingleObjectiveTestFunctionProblemEvaluator { public override string FunctionName { get { return "Sphere"; } } /// /// Returns false as the Sphere function is a minimization problem. /// public override bool Maximization { get { return false; } } /// /// Gets the optimum function value (0). /// public override double BestKnownQuality { get { return 0; } } /// /// Gets the lower and upper bound of the function. /// public override DoubleMatrix Bounds { get { return new DoubleMatrix(new double[,] { { -5.12, 5.12 } }); } } /// /// Gets the minimum problem size (1). /// public override int MinimumProblemSize { get { return 1; } } /// /// Gets the (theoretical) maximum problem size (2^31 - 1). /// public override int MaximumProblemSize { get { return int.MaxValue; } } public override IDeepCloneable Clone(Cloner cloner) { return new SphereEvaluator(this, cloner); } public override RealVector GetBestKnownSolution(int dimension) { return new RealVector(dimension); } /// /// The parameter C modifies the steepness of the objective function y = C * ||X||^Alpha. Default is C = 1. /// public ValueParameter CParameter { get { return (ValueParameter)Parameters["C"]; } } /// /// The parameter Alpha modifies the steepness of the objective function y = C * ||X||^Alpha. Default is Alpha = 2. /// public ValueParameter AlphaParameter { get { return (ValueParameter)Parameters["Alpha"]; } } /// /// The parameter C modifies the steepness of the objective function y = C * ||X||^Alpha. Default is C = 1. /// public DoubleValue C { get { return CParameter.Value; } set { if (value != null) CParameter.Value = value; } } /// /// The parameter Alpha modifies the steepness of the objective function y = C * ||X||^Alpha. Default is Alpha = 2. /// public DoubleValue Alpha { get { return AlphaParameter.Value; } set { if (value != null) AlphaParameter.Value = value; } } [StorableConstructor] protected SphereEvaluator(bool deserializing) : base(deserializing) { } protected SphereEvaluator(SphereEvaluator original, Cloner cloner) : base(original, cloner) { } /// /// Initializes a new instance of the SphereEvaluator with two parameters (C and Alpha). /// public SphereEvaluator() : base() { Parameters.Add(new ValueParameter("C", "The parameter C modifies the steepness of the objective function y = C * ||X||^Alpha. Default is C = 1.", new DoubleValue(1))); Parameters.Add(new ValueParameter("Alpha", "The parameter Alpha modifies the steepness of the objective function y = C * ||X||^Alpha. Default is Alpha = 2.", new DoubleValue(2))); } /// /// Evaluates the test function for a specific . /// /// N-dimensional point for which the test function should be evaluated. /// The result value of the Sphere function at the given point. public static double Apply(RealVector point, double c, double alpha) { double result = 0; for (int i = 0; i < point.Length; i++) result += point[i] * point[i]; if (alpha != 2) result = Math.Pow(Math.Sqrt(result), alpha); return c * result; } /// /// Evaluates the test function for a specific . /// /// Calls . /// N-dimensional point for which the test function should be evaluated. /// The result value of the Sphere function at the given point. public override double Evaluate(RealVector point) { return Apply(point, C.Value, Alpha.Value); } } }