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

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

/**
 * The Colville Function.
 *
 * Reference: Doo-Hyun Choi, Cooperative mutation based evolutionary programming for continuous function optimization, Operations Research Letters, Volume 30, Issue 3, June 2002, Pages 195-201/p>
 *
 * 
Minimum:
 * 

 *  f(x*) = 0
 *  x* = (1, 1, 1, 1)
 *  for x_i in [-10, 10]
 * 
 * 
 *
 * Characteristics:
 * 

 * Only defined for 4 dimensions
 * Unimodal
 * Non-separable
 * Regular
 * 
 * 
 *
 * R(-10, 10)^4
 *
 */
public class Colville extends ContinuousFunction {

    private static final long serialVersionUID = 4561331100889232057L;

    /**
     * {@inheritDoc}
     */
    @Override
    public Double f(Vector input) {
        Preconditions.checkArgument(input.size() == 4, "Colville function is only defined for 4 dimensions");

        double a = input.doubleValueOf(0);
        double b = input.doubleValueOf(1);
        double c = input.doubleValueOf(2);
        double d = input.doubleValueOf(3);

        return 100 * (a - b * b) * (a - b * b)
                + (1 - a) * (1 - a)
                + 90 * (d - c * c) * (d - c * c)
                + (1 - c) * (1 - c)
                + 10.1 * ((b - 1) * (b - 1) + (d - 1) * (d - 1))
                + 19.8 * (b - 1) * (d - 1);
    }
}