org.apache.commons.math3.analysis.function

Class Logistic

java.lang.Object

org.apache.commons.math3.analysis.function.Logistic

All Implemented Interfaces:

DifferentiableUnivariateFunction, UnivariateDifferentiableFunction, UnivariateFunction

public class Logistic
extends java.lang.Object
implements UnivariateDifferentiableFunction, DifferentiableUnivariateFunction

Generalised logistic function.

Since:

3.0

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Logistic.Parametric Parametric function where the input array contains the parameters of the logistic function, ordered as follows: k m b q a n

Field Summary

Fields

Modifier and Type	Field and Description
private double	a Lower asymptote.
private double	b Growth rate.
private double	k Upper asymptote.
private double	m Abscissa of maximum growth.
private double	oneOverN Parameter that affects near which asymptote maximum growth occurs.
private double	q Parameter that affects the position of the curve along the ordinate axis.

Constructor Summary

Constructors

Constructor and Description
Logistic(double k, double m, double b, double q, double a, double n)

Method Summary

Methods

Modifier and Type	Method and Description
UnivariateFunction	derivative() Deprecated. as of 3.1, replaced by value(DerivativeStructure)
DerivativeStructure	value(DerivativeStructure t) Simple mathematical function.
double	value(double x) Compute the value of the function.
private static double	value(double mMinusX, double k, double b, double q, double a, double oneOverN)

Methods inherited from class java.lang.Object

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

Field Detail

a

private final double a

Lower asymptote.

k

private final double k

Upper asymptote.

b

private final double b

Growth rate.

oneOverN

private final double oneOverN

Parameter that affects near which asymptote maximum growth occurs.

q

private final double q

Parameter that affects the position of the curve along the ordinate axis.

m

private final double m

Abscissa of maximum growth.

Constructor Detail

Logistic

public Logistic(double k,
        double m,
        double b,
        double q,
        double a,
        double n)
         throws NotStrictlyPositiveException

Parameters:

k - If b > 0, value of the function for x going towards +∞. If b < 0, value of the function for x going towards -∞.

m - Abscissa of maximum growth.

b - Growth rate.

q - Parameter that affects the position of the curve along the ordinate axis.

a - If b > 0, value of the function for x going towards -∞. If b < 0, value of the function for x going towards +∞.

n - Parameter that affects near which asymptote the maximum growth occurs.

Throws:

NotStrictlyPositiveException - if n <= 0.

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.

derivative

@Deprecated
public UnivariateFunction derivative()

Deprecated. as of 3.1, replaced by value(DerivativeStructure)

Returns the derivative of the function

Specified by:

derivative in interface DifferentiableUnivariateFunction

Returns:

the derivative function

value

private static double value(double mMinusX,
           double k,
           double b,
           double q,
           double a,
           double oneOverN)

Parameters:

mMinusX - m - x.

k - k.

b - b.

q - q.

a - a.

oneOverN - 1 / n.

Returns:

the value of the function.

value

public DerivativeStructure value(DerivativeStructure t)

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

Since:

3.1