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 Object

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

Since:

3.3

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

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

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.