F12Schwefel.java

//
// Special Session on Real-Parameter Optimization at CEC-05
// Edinburgh, UK, 2-5 Sept. 2005
//
// Organizers:
//	Prof. Kalyanmoy Deb
//		deb@iitk.ac.in
//		http://www.iitk.ac.in/kangal/deb.htm
//	A/Prof. P. N. Suganthan
//		epnsugan@ntu.edu.sg
//		http://www.ntu.edu.sg/home/EPNSugan
//
// Java version of the org.uma.test functions
//
// Matlab reference code
//	http://www.ntu.edu.sg/home/EPNSugan
//
// Java version developer:
//	Assistant Prof. Ying-ping Chen
//		Department of Computer Science
//		National Chiao Tung University
//		HsinChu City, Taiwan
//		ypchen@csie.nctu.edu.tw
//		http://www.csie.nctu.edu.tw/~ypchen/
//
// Typical use of the org.uma.test functions in the Benchmark:
//
//		// Create a Benchmark object
// 		Benchmark theBenchmark = new Benchmark();
//		// Use the factory function call to create a org.uma.test function object
//		//		org.uma.test function 3 with 50 dimension
//		//		the object class is "TestFunc"
//		TestFunc aTestFunc = theBenchmark.testFunctionFactory(3, 50);
//		// Invoke the function with x
//		double experimentoutput = aTestFunc.f(x);
//
// Version 0.90
//		Currently, this version cannot handle any numbers of dimensions.
//		It cannot generate the shifted global optima and rotation matrices
//		that are not provided with the Matlab reference code.
//		It can handle all cases whose data files are provided with
//		the Matlab reference code.
// Version 0.91
//		Revised according to the Matlab reference code and the PDF document
//		dated March 8, 2005.
//
package org.uma.jmetal.problem.singleobjective.cec2005competitioncode;

import org.uma.jmetal.util.JMetalException;

public class F12Schwefel extends TestFunc {

  // Fixed (class) parameters
  static final public String FUNCTION_NAME = "Schwefel's Problem 2.13";
  static final public String DEFAULT_FILE_DATA = Benchmark.CEC2005SUPPORTDATADIRECTORY + "/supportData/schwefel_213_data.txt";

  // Shifted global optimum
  private final double[] m_o;
  private final double[][] m_a;
  private final double[][] m_b;

  // In order to avoid excessive memory allocation,
  // a fixed memory buffer is allocated for each function object.
  private double[] m_A;
  private double[] m_B;

  // Constructors
  public F12Schwefel(int dimension, double bias) throws JMetalException {
    this(dimension, bias, DEFAULT_FILE_DATA);
  }

  public F12Schwefel(int dimension, double bias, String file_data) throws JMetalException {
    super(dimension, bias, FUNCTION_NAME);

    // Note: dimension starts from 0
    m_o = new double[mDimension];
    m_a = new double[mDimension][mDimension];
    m_b = new double[mDimension][mDimension];

    m_A = new double[mDimension];
    m_B = new double[mDimension];

    // Data:
    //	1. a 		100x100
    //	2. b 		100x100
    //	3. alpha	1x100
    double[][] m_data = new double[100 + 100 + 1][mDimension];

    // Load the shifted global optimum
    Benchmark.loadMatrixFromFile(file_data, m_data.length, mDimension, m_data);
    for (int i = 0; i < mDimension; i++) {
      for (int j = 0; j < mDimension; j++) {
        m_a[i][j] = m_data[i][j];
        m_b[i][j] = m_data[100 + i][j];
      }
      m_o[i] = m_data[100 + 100][i];
    }

    for (int i = 0; i < mDimension; i++) {
      m_A[i] = 0.0;
      for (int j = 0; j < mDimension; j++) {
        m_A[i] += (m_a[i][j] * Math.sin(m_o[j]) + m_b[i][j] * Math.cos(m_o[j]));
      }
    }
  }

  // Function body
  public double f(double[] x) {

    double sum = 0.0;

    for (int i = 0; i < mDimension; i++) {
      m_B[i] = 0.0;
      for (int j = 0; j < mDimension; j++) {
        m_B[i] += (m_a[i][j] * Math.sin(x[j]) + m_b[i][j] * Math.cos(x[j]));
      }

      double temp = m_A[i] - m_B[i];
      sum += (temp * temp);
    }

    return (sum + mBias);
  }
}