org.encog.engine.network.activation

Class ActivationReLU

java.lang.Object

org.encog.engine.network.activation.ActivationReLU

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable, ActivationFunction

public class ActivationReLU
extends java.lang.Object
implements ActivationFunction

A ramp activation function. This function has a high and low threshold. If the high threshold is exceeded a fixed value is returned. Likewise, if the low value is exceeded another fixed value is returned.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static int	PARAM_RELU_LOW The ramp low parameter.
static int	PARAM_RELU_LOW_THRESHOLD The ramp low threshold parameter.

Constructor Summary

Constructors

Constructor and Description
ActivationReLU() Default constructor.
ActivationReLU(double thresholdLow, double low) Construct a ramp activation function.

Method Summary

Modifier and Type	Method and Description
void	activationFunction(double[] x, int start, int size) Implements the activation function.
ActivationFunction	clone() Clone the object.
double	derivativeFunction(double b, double a) Calculate the derivative.
java.lang.String	getFactoryCode()
java.lang.String	getLabel()
double	getLow()
java.lang.String[]	getParamNames()
double[]	getParams()
double	getThresholdLow()
boolean	hasDerivative()
void	setLow(double d) Set the low value.
void	setParam(int index, double value) Set one of the params for this activation function.
void	setThresholdLow(double d) Set the threshold low.

Methods inherited from class java.lang.Object

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

Field Detail

PARAM_RELU_LOW_THRESHOLD

public static final int PARAM_RELU_LOW_THRESHOLD

The ramp low threshold parameter.

See Also:

Constant Field Values

PARAM_RELU_LOW

public static final int PARAM_RELU_LOW

The ramp low parameter.

See Also:

Constant Field Values

Constructor Detail

ActivationReLU

public ActivationReLU()

Default constructor.

ActivationReLU

public ActivationReLU(double thresholdLow,
                      double low)

Construct a ramp activation function.

Parameters:

thresholdLow - The low threshold value.

low - The low value, replaced if the low threshold is exceeded.

Method Detail

activationFunction

public final void activationFunction(double[] x,
                                     int start,
                                     int size)

Implements the activation function. The array is modified according to the activation function being used. See the class description for more specific information on this type of activation function.

Specified by:

activationFunction in interface ActivationFunction

Parameters:

x - The input array to the activation function.

start - The starting index.

size - The number of values to calculate.

clone

public final ActivationFunction clone()

Clone the object.

Specified by:

clone in interface ActivationFunction

Overrides:

clone in class java.lang.Object

Returns:

The cloned object.

derivativeFunction

public final double derivativeFunction(double b,
                                       double a)

Calculate the derivative. For performance reasons two numbers are provided. First, the value "b" is simply the number that we would like to calculate the derivative of. Second, the value "a", which is the value returned by the activation function, when presented with "b". We use two values because some of the most common activation functions make use of the result of the activation function. It is bad for performance to calculate this value twice. Yet, not all derivatives are calculated this way. By providing both the value before the activation function is applied ("b"), and after the activation function is applied("a"), the class can be constructed to use whichever value will be the most efficient.

Specified by:

derivativeFunction in interface ActivationFunction

Parameters:

b - The number to calculate the derivative of, the number "before" the activation function was applied.

a - The number "after" an activation function has been applied.

Returns:

The derivative.

getLow

public final double getLow()

Returns:

the low

getParamNames

public final java.lang.String[] getParamNames()

Specified by:

getParamNames in interface ActivationFunction

Returns:

The names of the parameters.

getParams

public final double[] getParams()

Specified by:

getParams in interface ActivationFunction

Returns:

The params for this activation function.

getThresholdLow

public final double getThresholdLow()

Returns:

the thresholdLow

hasDerivative

public final boolean hasDerivative()

Specified by:

hasDerivative in interface ActivationFunction

Returns:

True, as this function does have a derivative.

setLow

public final void setLow(double d)

Set the low value.

Parameters:

d - The low value.

setParam

public final void setParam(int index,
                           double value)

Set one of the params for this activation function.

Specified by:

setParam in interface ActivationFunction

Parameters:

index - The index of the param to set.

value - The value to set.

setThresholdLow

public final void setThresholdLow(double d)

Set the threshold low.

Parameters:

d - The threshold low.

getFactoryCode

public java.lang.String getFactoryCode()

Specified by:

getFactoryCode in interface ActivationFunction

Returns:

The string for the Encog factory code. Return null if you do not care to be support for creating of your activation through factory.

getLabel

public java.lang.String getLabel()

Specified by:

getLabel in interface ActivationFunction

Returns:

The human-friendly name for this activation