net.sourceforge.cilib.functions.continuous.unconstrained
Class Rastrigin

java.lang.Object
  net.sourceforge.cilib.functions.Function
      net.sourceforge.cilib.functions.ContinuousFunction
          net.sourceforge.cilib.functions.continuous.unconstrained.Rastrigin

All Implemented Interfaces:

Serializable, Differentiable, Cloneable

public class Rastrigin
extends ContinuousFunction
implements Differentiable

The rastrigin function.

Reference: X. Yao and Y. Liu and G. Liu, Evolutionary Programming Made Faster, IEEE Transactions on Evolutionary Computation, vol 3, number 2, pages 82--102, 1999.

Characteristics:

• Multimodal
• Continuous
• Seperable

f(x) = 0; x = (0,0,...,0); x e [-5.12, 5.12];

Author:

Edwin Peer

See Also:

Serialized Form

Constructor Summary

Rastrigin()
Create an instance of the Rastrigin function.

Method Summary

double	evaluate(Vector x) Evaluate the function with the given Vector as input.
Rastrigin	getClone() Create a cloned copy of the current object and return it.
Vector	getGradient(Vector x) Obtain the gradient Vector for the provided input Vector.
Object	getMinimum() Accessor for the function minimum.

Methods inherited from class net.sourceforge.cilib.functions.ContinuousFunction

evaluate, getMaximum

Methods inherited from class net.sourceforge.cilib.functions.Function

getBehavioralDomainRegistry, getDimension, getDomain, getDomainRegistry, setBehavioralDomain, setBehaviouralDomainRegistry, setDomain

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Rastrigin

public Rastrigin()

Create an instance of the Rastrigin function. The default domain is defined to be R(-5.12, 5.12)^30

Method Detail

getClone

public Rastrigin getClone()

Create a cloned copy of the current object and return it. In general the created copy will be a deep copy of the provided instance. As a result this operation an be quite expensive if used incorrectly.

Specified by:

getClone in interface Cloneable

Specified by:

getClone in class ContinuousFunction

Returns:

An exact clone of the current object instance.

See Also:

Object.clone()

getMinimum

public Object getMinimum()

Accessor for the function minimum. This is the minimum value of the function in the given domain.

Overrides:

getMinimum in class ContinuousFunction

Returns:

The minimum function value.

evaluate

public double evaluate(Vector x)

Evaluate the function with the given Vector as input.

Specified by:

evaluate in class ContinuousFunction

Parameters:

x - The input Vector.

Returns:

The value of the evaluation.

getGradient

public Vector getGradient(Vector x)

Obtain the gradient Vector for the provided input Vector. The gradient is, naturally, the derivative of the Function which implements this interface.

Specified by:

getGradient in interface Differentiable

Parameters:

x - The provided input Vector to calculate the derivative at.

Returns:

A Vector containing the gradient of the provided input.