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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>
/// Penalized1 benchmark problem.
/// </summary>
public class Penalized1 : 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 Penalized1(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 "Penalized1"; }
}
/// <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 = GetSinY(x[0]);
int i;
for (i = 0; i < Dimensionality - 1; i++)
{
double elmY = GetY(x[i]);
double elmYMinusOne = elmY - 1;
value += (elmYMinusOne * elmYMinusOne) * (1 + GetSinY(x[i + 1]));
}
// Add last y-term.
{
double elmY = GetY(x[Dimensionality - 1]);
double elmYMinusOne = elmY - 1;
value += elmYMinusOne * elmYMinusOne;
}
// Compute penalty.
double penalty = 0;
for (i = 0; i < Dimensionality; i++)
{
double elm = x[i];
penalty += U(elm, 10.0, 100.0, 4.0);
}
return System.Math.PI * value / Dimensionality + penalty;
}
#endregion
#region Helper methods.
/// <summary>
/// Helper-method used in Fitness method.
/// </summary>
protected double GetY(double x)
{
return 1 + 0.25 * (x + 1);
}
/// <summary>
/// Helper-method used in Fitness method.
/// </summary>
protected double GetSinY(double x)
{
double elmY = GetY(x);
double elmSinY = System.Math.Sin(System.Math.PI * elmY);
return 10 * elmSinY * elmSinY;
}
#endregion
}
}
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