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/// SwarmOps - Numeric and heuristic optimization for C#
/// Copyright (C) 2003-2011 Magnus Erik Hvass Pedersen.
/// Please see the file license.txt for license details.
/// SwarmOps on the internet: http://www.Hvass-Labs.org/
/// ------------------------------------------------------
using System.Diagnostics;
namespace SwarmOps.Problems
{
/// <summary>
/// Penalized2 benchmark problem.
/// </summary>
public class Penalized2 : Penalized
{
#region Constructors.
/// <summary>
/// Construct the object.
/// </summary>
/// <param name="dimensionality">Dimensionality of the problem (e.g. 20)</param>
/// <param name="maxIterations">Max optimization iterations to perform.</param>
public Penalized2(int dimensionality, int maxIterations)
: base(dimensionality, -50, 50, -5, 50, maxIterations)
{
}
#endregion
#region Base-class overrides.
/// <summary>
/// Name of the optimization problem.
/// </summary>
public override string Name
{
get { return "Penalized2"; }
}
/// <summary>
/// Minimum possible fitness.
/// </summary>
public override double MinFitness
{
get { return 0; }
}
/// <summary>
/// Compute and return fitness for the given parameters.
/// </summary>
/// <param name="x">Candidate solution.</param>
public override double Fitness(double[] x)
{
Debug.Assert(x != null && x.Length == Dimensionality);
// Compute main fitness value ...
double value = GetSinX(x[0], 3.0);
int i;
for (i = 0; i < Dimensionality - 1; i++)
{
double elm = x[i];
double elmMinusOne = elm - 1;
double elmSin = GetSinX(x[i + 1], 3.0);
value += (elmMinusOne * elmMinusOne) * (1 + elmSin);
}
// Add last term.
{
double elm = x[Dimensionality - 1];
double elmMinusOne = elm - 1;
double elmSin = GetSinX(elm, 2.0);
value += elmMinusOne * elmMinusOne * (1 + elmSin);
}
// Compute penalty.
double penalty = 0;
for (i = 0; i < Dimensionality; i++)
{
double elm = x[i];
penalty += U(elm, 5.0, 100.0, 4.0);
}
return 0.1 * value + penalty;
}
#endregion
#region Helper methods.
/// <summary>
/// Helper-method used in Fitness method.
/// </summary>
protected double GetSinX(double x, double factor)
{
double elmSin = System.Math.Sin(factor * System.Math.PI * x);
return elmSin * elmSin;
}
#endregion
}
}
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