C# Class AForge.Neuro.SigmoidFunction

Sigmoid activation function.

The class represents sigmoid activation function with the next expression: 1 f(x) = ------------------ 1 + exp(-alpha * x) alpha * exp(-alpha * x ) f'(x) = ---------------------------- = alpha * f(x) * (1 - f(x)) (1 + exp(-alpha * x))^2

Output range of the function: [0, 1].

Functions graph:

Inheritance: IActivationFunction
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Public Methods

Method Description
Clone ( ) : object

Creates a new object that is a copy of the current instance.

Derivative ( double x ) : double

Calculates function derivative.

The method calculates function derivative at point x.

Derivative2 ( double y ) : double

Calculates function derivative.

The method calculates the same derivative value as the Derivative method, but it takes not the input x value itself, but the function value, which was calculated previously with the help of Function method.

Some applications require as function value, as derivative value, so they can save the amount of calculations using this method to calculate derivative.

Function ( double x ) : double

Calculates function value.

The method calculates function value at point x.

SigmoidFunction ( ) : System

Initializes a new instance of the SigmoidFunction class.

SigmoidFunction ( double alpha ) : System

Initializes a new instance of the SigmoidFunction class.

Method Details

Clone() public method

Creates a new object that is a copy of the current instance.
public Clone ( ) : object
return object

Derivative() public method

Calculates function derivative.
The method calculates function derivative at point x.
public Derivative ( double x ) : double
x double Function input value.
return double

Derivative2() public method

Calculates function derivative.

The method calculates the same derivative value as the Derivative method, but it takes not the input x value itself, but the function value, which was calculated previously with the help of Function method.

Some applications require as function value, as derivative value, so they can save the amount of calculations using this method to calculate derivative.

public Derivative2 ( double y ) : double
y double Function output value - the value, which was obtained /// with the help of method.
return double

Function() public method

Calculates function value.
The method calculates function value at point x.
public Function ( double x ) : double
x double Function input value.
return double

SigmoidFunction() public method

Initializes a new instance of the SigmoidFunction class.
public SigmoidFunction ( ) : System
return System

SigmoidFunction() public method

Initializes a new instance of the SigmoidFunction class.
public SigmoidFunction ( double alpha ) : System
alpha double Sigmoid's alpha value.
return System