org.apache.commons.math3.ml.neuralnet.sofm.util

Class ExponentialDecayFunction

java.lang.Object

org.apache.commons.math3.ml.neuralnet.sofm.util.ExponentialDecayFunction

public class ExponentialDecayFunction
extends java.lang.Object

Exponential decay function: a e-x / b, where x is the (integer) independent variable.
Class is immutable.

Since:

3.3

Field Summary

Fields

Modifier and Type	Field and Description
private double	a Factor a.
private double	oneOverB Factor 1 / b.

Constructor Summary

Constructors

Constructor and Description
ExponentialDecayFunction(double initValue, double valueAtNumCall, long numCall) Creates an instance.

Method Summary

Modifier and Type	Method and Description
double	value(long numCall) Computes a e-numCall / b.

Methods inherited from class java.lang.Object

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

Field Detail

a

private final double a

Factor a.

oneOverB

private final double oneOverB

Factor 1 / b.

Constructor Detail

ExponentialDecayFunction

public ExponentialDecayFunction(double initValue,
                                double valueAtNumCall,
                                long numCall)

Creates an instance. It will be such that

• a = initValue
• b = -numCall / ln(valueAtNumCall / initValue)

Parameters:

initValue - Initial value, i.e. value(0).

valueAtNumCall - Value of the function at numCall.

numCall - Argument for which the function returns valueAtNumCall.

Throws:

NotStrictlyPositiveException - if initValue <= 0.

NotStrictlyPositiveException - if valueAtNumCall <= 0.

NumberIsTooLargeException - if valueAtNumCall >= initValue.

NotStrictlyPositiveException - if numCall <= 0.

Method Detail

value

public double value(long numCall)

Computes a e-numCall / b.

Parameters:

numCall - Current step of the training task.

Returns:

the value of the function at numCall.