# Class Sigmoid

java.lang.Object
org.hipparchus.analysis.function.Sigmoid
All Implemented Interfaces:
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.
• ## 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.
<T extends Derivative<T>>T
value(T t)
Compute the value for the 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 <T extends Derivative<T>> T value(T t) throws MathIllegalArgumentException
Compute the value for the function.
Specified by:
value in interface UnivariateDifferentiableFunction
Type Parameters:
T - the type of the field elements
Parameters:
t - the point for which the function value should be computed
Returns:
the value
Throws:
MathIllegalArgumentException - if x does not satisfy the function's constraints (argument out of bound, or unsupported derivative order for example)