Function (boone)

java.lang.Object
- boone.map.Function

All Implemented Interfaces:

Storable, java.lang.Cloneable

Direct Known Subclasses:

Function.AboutEqual, Function.AtLeast, Function.AtMost, Function.CatmullRomSpline, Function.Clip, Function.Composition, Function.Exponential, Function.GreaterThan, Function.Identity, Function.LessThan, Function.NaturalSpline, Function.ReLU, Function.Scaled, Function.Sigmoid, Function.Signum, Function.SignumWithoutZero, Function.Sinus, Function.SoftMax, Function.TanH, NeuronPotential, PostsynapticPotential, Spike
```
public abstract class Function
extends java.lang.Object
implements java.lang.Cloneable, Storable
```
A function that generates an output value from input values.
NOTE: - subclasses should implement a constructor without parameters, so that Functions can be instantiated by serialization.

Version:

$Id$

Author:

August Mayer

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`Function.AboutEqual` About Equal: return 1.0 `if (eqValue - range) < value < (eqValue + range)`.
`static class`	`Function.AtLeast` At Least: return 1.0 `if value >= minValue, 0.0 else`.
`static class`	`Function.AtMost` At Most: return 1.0 `if value <= maxValue, 0.0 else`.
`static class`	`Function.CatmullRomSpline` Catmull-Rom Spline Activation Function.
`static class`	`Function.Clip` Clip: return value if value in the given range, else the low/high range border value.
`static class`	`Function.Composition` composition function, returns g(f(x)).
`static class`	`Function.Exponential` The plain exponential function f(x) = e^x with caching.
`static class`	`Function.GreaterThan` Greater Than (strict): return 1.0 `if value > minValue, 0.0 else`.
`static class`	`Function.Identity` identity function - maps input to output
`static class`	`Function.LessThan` Less Than (strict): return 1.0 `if value < maxValue, 0.0 else`.
`static class`	`Function.NaturalSpline` Natural Cubic Spline Activation Function
`static class`	`Function.NotImplemented` Runtime exception to throw for something that is not implemented.
`static class`	`Function.ReLU` The rectified linear unit (ReLU) function f(x) = max(0, x) with first derivative.
`static class`	`Function.Scaled` function adding scaling factors, applied to the function result value (outside).
`static class`	`Function.Sigmoid` The sigmoid function f(x) = 1 / (1 + e^(-x)) with first and second derivative.
`static class`	`Function.Signum` Signum: `1 if > 0, -1 if < 0, 0 if = 0`
`static class`	`Function.SignumWithoutZero` Signum Without Zero: 1 `if > 0, -1 else`
`static class`	`Function.Sinus` Sinus: sin(factor * x) Default: factor = 0.1 First and Second Derivatives are implemented.
`static class`	`Function.SoftMax` The softmax function mapping an array of values to a probability distribution by f(xi) = e^(xi) / sumi(e^(xi)).
`static interface`	`Function.Spline` Spline function interface.
`static class`	`Function.TanH` The tanh function f(x) = (e^x - e^-x) / (e^x + e^-x) with caching and fast, numerically safe computation.

Constructor Summary

Constructors
Constructor and Description

Function()

Constructors
Constructor and Description
`Function()`

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`Function`	`clone()` Return a deep copy of this object.
`static Function`	`create(java.lang.String name)` Create a function, given its name.
`void`	`fromXML(org.jdom2.Element element)` Reads attributes from XML tree.
`abstract double`	`getMaxValue()` Return the largest possible function value.
`abstract double`	`getMinValue()` Return the smallest possible function value.
`double`	`map(double value)` Map a value through the function.
`double`	`mapDerivative(double value)` Map a value through the first derivative of this function.
`double`	`mapSecondDerivative(double value)` Map a value through the second derivative of this function.
`void`	`setParameters(java.lang.Object params)` Set parameters, if needed.
`org.jdom2.Element`	`toXML(org.jdom2.Element element)` Adds a function element to XML.

Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - Function
```
public Function()
```
- Method Detail
  - create
```
public static Function create(java.lang.String name)
```
    Create a function, given its name. The name is the basic class name, without packages or outer classes. Exceptions are reported using ExceptionHandler.
    
    TODO: handle singleton classes.
    
    Parameters:
    
    name - Name of the function to create.
    
    Returns:
    
    New function object for the given class, or null.
  - setParameters
```
public void setParameters(java.lang.Object params)
```
    Set parameters, if needed.
    
    Parameters:
    
    params - the parameters
  - map
```
public double map(double value)
```
    Map a value through the function.
  - mapDerivative
```
public double mapDerivative(double value)
```
    Map a value through the first derivative of this function.
    
    Throws:
    
    Function.NotImplemented - if not implemented (this is a RuntimeException).
  - mapSecondDerivative
```
public double mapSecondDerivative(double value)
```
    Map a value through the second derivative of this function.
    
    Throws:
    
    Function.NotImplemented - if not implemented (this is a RuntimeException).
  - getMinValue
```
public abstract double getMinValue()
```
    Return the smallest possible function value. If no exact value can be produced easily, this should return an estimation (lower bound).
    
    Returns:
    
    the minimum function result.
  - getMaxValue
```
public abstract double getMaxValue()
```
    Return the largest possible function value. If no exact value can be produced easily, this should return an estimation (upper bound).
    
    Returns:
    
    the maximum function result.
  - clone
```
public Function clone()
```
    Return a deep copy of this object. By default, just calls super.clone().
    
    Overrides:
    
    clone in class java.lang.Object
    
    Throws:
    
    CloneException - if cloning fails internally.
  - toXML
```
public org.jdom2.Element toXML(org.jdom2.Element element)
```
    Adds a function element to XML.
    
    Specified by:
    
    toXML in interface Storable
    
    Parameters:
    
    element - the parent element
    
    Returns:
    
    the function element
  - fromXML
```
public void fromXML(org.jdom2.Element element)
```
    Description copied from interface: Storable
    
    Reads attributes from XML tree.
    
    Specified by:
    
    fromXML in interface Storable
    
    Parameters:
    
    element - a JDOM element

Class Function

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Function

Method Detail

create

setParameters

map

mapDerivative

mapSecondDerivative

getMinValue

getMaxValue

clone

toXML

fromXML