Sigmoid (Apache Commons Math 4.0-SNAPSHOT)

java.lang.Object
- org.apache.commons.math4.legacy.analysis.function.Sigmoid

All Implemented Interfaces:

DoubleUnaryOperator, UnivariateDifferentiableFunction, UnivariateFunction
```
public class Sigmoid
extends 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.

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

All Methods Instance Methods Concrete Methods
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

Methods inherited from interface java.util.function.DoubleUnaryOperator
andThen, compose

Methods inherited from interface org.apache.commons.math4.legacy.analysis.UnivariateFunction
applyAsDouble

- Constructor Detail
  - 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 Detail
  - 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