Package org.apache.commons.math4.neuralnet.sofm

Class LearningFactorFunctionFactory

java.lang.Object

org.apache.commons.math4.neuralnet.sofm.LearningFactorFunctionFactory

public final class LearningFactorFunctionFactory
extends Object

Factory for creating instances of LearningFactorFunction.

Since:

3.3

Method Summary

Modifier and Type	Method	Description
static LearningFactorFunction	exponentialDecay(double initValue, double valueAtNumCall, long numCall)	Creates an exponential decay function.
static LearningFactorFunction	quasiSigmoidDecay(double initValue, double slope, long numCall)	Creates an sigmoid-like LearningFactorFunction function.

Methods inherited from class java.lang.Object

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

Method Detail

exponentialDecay

public static LearningFactorFunction exponentialDecay(double initValue,
                                                      double valueAtNumCall,
                                                      long numCall)

Creates an exponential decay function. It will compute a e-x / b, where x is the (integer) independent variable and

• 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.

Returns:

the learning factor function.

Throws:

IllegalArgumentException - if initValue <= 0, initValue > 1 valueAtNumCall <= 0, valueAtNumCall >= initValue or numCall <= 0.

quasiSigmoidDecay

public static LearningFactorFunction quasiSigmoidDecay(double initValue,
                                                       double slope,
                                                       long numCall)

Creates an sigmoid-like LearningFactorFunction function. The function f will have the following properties:

• f(0) = initValue
• numCall is the inflexion point
• slope = f'(numCall)

Parameters:

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

slope - Value of the function derivative at numCall.

numCall - Inflexion point.

Returns:

the learning factor function.

Throws:

IllegalArgumentException - if initValue <= 0, initValue > 1, slope >= 0 or numCall <= 0.