net.sourceforge.cilib.functions.continuous.unconstrained.Waves Maven / Gradle / Ivy

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/**           __  __
 *    _____ _/ /_/ /_    Computational Intelligence Library (CIlib)
 *   / ___/ / / / __ \   (c) CIRG @ UP
 *  / /__/ / / / /_/ /   http://cilib.net
 *  \___/_/_/_/_.___/
 */

package net.sourceforge.cilib.functions.continuous.unconstrained;

import net.sourceforge.cilib.functions.ContinuousFunction;
import net.sourceforge.cilib.type.types.container.Vector;

import com.google.common.base.Preconditions;

/**
 * Waves Function.
 *
 * Global Minimum:
 * 

 * f(x,y) = 0
 * Many global minima where ever x = 0
 * 
 * 
 *
 * Characteristics:
 * 

 * Only defined for 2 dimensions
 * Multimodal
 * Non-Separable
 * One global optimum, and nine local optima
 * 
 * 
 *
 * R(-0.9,1.2), R(-1.2,1.2)
 *
 */
public class Waves extends ContinuousFunction {
    /**
     * {@inheritDoc}
     */
    @Override
    public Double f(Vector input) {
        Preconditions.checkArgument(input.size() == 2, "Waves function is only defined for 2 dimensions");

        double x = input.doubleValueOf(0);
        double y = input.doubleValueOf(1);

        return -(Math.pow(0.3*x, 3)-(y*y-4.5*y*y)*x*y-4.7*Math.cos(3*x-y*y*(2+x))*Math.sin(2.5*Math.PI*x));
    }
}