## Class 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
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