org.nd4j.linalg.activations.impl

Class ActivationSigmoid

java.lang.Object

org.nd4j.linalg.activations.BaseActivationFunction

org.nd4j.linalg.activations.impl.ActivationSigmoid

All Implemented Interfaces:

Serializable, IActivation

public class ActivationSigmoid
extends BaseActivationFunction

f(x) = 1 / (1 + exp(-x))

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ActivationSigmoid()

Method Summary

Modifier and Type	Method and Description
org.nd4j.linalg.primitives.Pair<INDArray,INDArray>	backprop(INDArray in, INDArray epsilon) Backpropagate the errors through the activation function, given input z and epsilon dL/da. Returns 2 INDArrays: (a) The gradient dL/dz, calculated from dL/da, and (b) The parameter gradients dL/dw, where w is the weights in the activation function.
INDArray	getActivation(INDArray in, boolean training) Carry out activation function on the input array (usually known as 'preOut' or 'z') Implementations must overwrite "in", transform in place and return "in" Can support separate behaviour during test
String	toString()

Methods inherited from class org.nd4j.linalg.activations.BaseActivationFunction

getGradientViewArray, getParametersViewArray, numParams, setGradientViewArray, setParametersViewArray

Methods inherited from class java.lang.Object

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

Constructor Detail

ActivationSigmoid

public ActivationSigmoid()

Method Detail

getActivation

public INDArray getActivation(INDArray in,
                              boolean training)

Description copied from interface: IActivation

Carry out activation function on the input array (usually known as 'preOut' or 'z') Implementations must overwrite "in", transform in place and return "in" Can support separate behaviour during test

Returns:

transformed activation

backprop

public org.nd4j.linalg.primitives.Pair<INDArray,INDArray> backprop(INDArray in,
                                                                   INDArray epsilon)

Description copied from interface: IActivation

Backpropagate the errors through the activation function, given input z and epsilon dL/da.
Returns 2 INDArrays:
(a) The gradient dL/dz, calculated from dL/da, and
(b) The parameter gradients dL/dw, where w is the weights in the activation function. For activation functions with no gradients, this will be null.

Parameters:

in - Input, before applying the activation function (z, or 'preOut')

epsilon - Gradient to be backpropagated: dL/da, where L is the loss function

Returns:

dL/dz and dL/dw, for weights w (null if activatino function has no weights)

toString

public String toString()

Overrides:

toString in class Object