org.cognity.math.functions

Class FastSigmoid

java.lang.Object

org.cognity.math.functions.FastSigmoid

All Implemented Interfaces:

Serializable, Function, ParametrizedFunction

public final class FastSigmoid
extends Object
implements ParametrizedFunction, Serializable

Implements a sigmoid function defined as follows:

Where is a constant defined by user. The default value is equal to 2.0.
This implementation uses a fast approximation of the exp(x) function. For more information, see this paper.

Author:

Artur Markiewicz

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static double	DEFAULT_PARAM

Constructor Summary

Constructors

Constructor and Description
FastSigmoid()
FastSigmoid(double param)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	equals(Object obj) Two functions are equal if they return the same values for all possible arguments.
double	getDeriv(double arg) Returns a value of the first derivative of the function for the given argument.
double	getParam() Returns the beta parameter
double	getValue(double arg) Returns a value of the function for the given argument.
boolean	hasDeriv() Returns true if the function is differentiable.
int	hashCode()
void	setParam(double param) Sets the beta parameter.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

DEFAULT_PARAM

public static final double DEFAULT_PARAM

See Also:

Constant Field Values

Constructor Detail

FastSigmoid

public FastSigmoid()

FastSigmoid

public FastSigmoid(double param)

Method Detail

getValue

public double getValue(double arg)

Description copied from interface: Function

Returns a value of the function for the given argument.

Specified by:

getValue in interface Function

Parameters:

arg - the argument

Returns:

the value of the function for the given argument

getDeriv

public double getDeriv(double arg)

Description copied from interface: Function

Returns a value of the first derivative of the function for the given argument.

Specified by:

getDeriv in interface Function

Parameters:

arg - the argument

Returns:

the value of the first derivative of the function for the given argument

hasDeriv

public boolean hasDeriv()

Description copied from interface: Function

Returns true if the function is differentiable.

Specified by:

hasDeriv in interface Function

Returns:

• true - if the function has a first derivative
• false - if the function hasn't a first derivative

getParam

public double getParam()

Returns the beta parameter

Specified by:

getParam in interface ParametrizedFunction

Returns:

beta

setParam

public void setParam(double param)

Sets the beta parameter.

Specified by:

setParam in interface ParametrizedFunction

Parameters:

param - beta

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object obj)

Two functions are equal if they return the same values for all possible arguments.

Overrides:

equals in class Object

Parameters:

obj - the object to compare

Returns:

true if objects are equal

hashCode

public int hashCode()

Overrides:

hashCode in class Object