Package org.apache.commons.math4.analysis.function

Class Sigmoid

java.lang.Object

org.apache.commons.math4.analysis.function.Sigmoid

All Implemented Interfaces:

UnivariateDifferentiableFunction, UnivariateFunction

public class Sigmoid
extends java.lang.Object
implements UnivariateDifferentiableFunction

Sigmoid function. It is the inverse of the logit function. A more flexible version, the generalised logistic, is implemented by the Logistic class.

Since:

3.0

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Sigmoid.Parametric	Parametric function where the input array contains the parameters of the sigmoid function, ordered as follows: Lower asymptote Higher asymptote

Constructor Summary

Constructors

Constructor	Description
Sigmoid()	Usual sigmoid function, where the lower asymptote is 0 and the higher asymptote is 1.
Sigmoid(double lo, double hi)	Sigmoid function.

Method Summary

Modifier and Type	Method	Description
double	value(double x)	Compute the value of the function.
DerivativeStructure	value(DerivativeStructure t)	Simple mathematical function.

Methods inherited from class java.lang.Object

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

Constructor Details

Sigmoid

public Sigmoid()

Usual sigmoid function, where the lower asymptote is 0 and the higher asymptote is 1.

Sigmoid

public Sigmoid(double lo, double hi)

Sigmoid function.

Parameters:

lo - Lower asymptote.

hi - Higher asymptote.

Method Details

value

public double value(double x)

Compute the value of the function.

Specified by:

value in interface UnivariateFunction

Parameters:

x - Point at which the function value should be computed.

Returns:

the value of the function.

value

public DerivativeStructure value(DerivativeStructure t) throws DimensionMismatchException

Simple mathematical function.

UnivariateDifferentiableFunction classes compute both the value and the first derivative of the function.

Specified by:

value in interface UnivariateDifferentiableFunction

Parameters:

t - function input value

Returns:

function result

Throws:

DimensionMismatchException - if t is inconsistent with the function's free parameters or order

Since:

3.1