net.sourceforge.cilib.functions.continuous.unconstrained.Bohachevsky1 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;

/**
 * Bohachevsky 1.
 *
 * Reference: Global Optimization Meta-Heuristics Website,
 * http://www-optima.amp.i.kyoto-u.ac.jp/member/student/hedar/Hedar_files/go.htm
 *
 * Minimum:
 * 

 *  ƒ(x*) = 0 
 *  x* = (0, 0)
 *  for x₁, x₂ in [-100, 100]
 * 
 * 
 *
 * Characteristics:
 * 

 * Only defined for 2 dimensions
 * Unimodal
 * Seperable
 * Regular
 * 
 * 
 *
 * R(-100, 100)^2
 *
 */
public class Bohachevsky1 extends ContinuousFunction {

    private static final long serialVersionUID = 44382638223225638L;

    /**
     * {@inheritDoc}
     */
    @Override
    public Double f(Vector input) {
        Preconditions.checkArgument(input.size() == 2, "Bohachevsky 1 function is only defined for 2 dimensions");

        double x = input.doubleValueOf(0);
        double y = input.doubleValueOf(1);
        return x * x + 2 * y * y - 0.3 * Math.cos(3 * Math.PI * x) - 0.4 * Math.cos(4 * Math.PI * y) + 0.7;
    }
}