/* Copyright 2009-2016 David Hadka
 *
 * This file is part of the MOEA Framework.
 *
 * The MOEA Framework is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 *
 * The MOEA Framework 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 Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with the MOEA Framework.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.moeaframework.problem.BBOB2016;

import org.moeaframework.core.Solution;

/* 
 * The following source code is derived from the Coco Framework available at
 * <https://github.com/numbbo/coco> under the 3-clause BSD license. The
 * original code is copyright 2013 by the NumBBO/CoCO team.  See the AUTHORS
 * file located in the Coco Framework repository for more details.
 */

/**
 * Transformation that oscillates the objective values of the inner function.
 */
public class TransformObjectiveOscillate extends BBOBTransformation {
	
	/**
	 * Controls the frequency of the oscillation.
	 */
	public static final double ALPHA = 0.1;
	
	/**
	 * Constructs a new instance of the oscillation transformation.
	 * 
	 * @param function the inner function
	 */
	public TransformObjectiveOscillate(BBOBFunction function) {
		super(function);
	}

	@Override
	public void evaluate(Solution solution) {
		function.evaluate(solution);
		
		for (int i = 0; i < numberOfObjectives; i++) {
			double y = solution.getObjective(i);
			
			if (y != 0.0) {
				double tmp = Math.log(Math.abs(y)) / ALPHA;
				
				if (y > 0.0) {
					double base = Math.exp(tmp + 0.49*(Math.sin(tmp) + Math.sin(0.79*tmp)));
					y = Math.pow(base, ALPHA);
				} else if (y < 0.0) {
					double base = Math.exp(tmp + 0.49*(Math.sin(0.55*tmp) + Math.sin(0.31*tmp)));
					y = -Math.pow(base, ALPHA);
				}
			}
			
			solution.setObjective(i, y);
		}
	}

}