org.apache.commons.math.analysis.function
Class Logistic

java.lang.Object
  org.apache.commons.math.analysis.function.Logistic

All Implemented Interfaces:

DifferentiableUnivariateRealFunction, UnivariateRealFunction

public class Logistic
extends java.lang.Object
implements DifferentiableUnivariateRealFunction

Generalised logistic function.

Since:

3.0

Version:

$Id$

Nested Class Summary

static class

Logistic.Parametric Parametric function where the input array contains the parameters of the logit function, ordered as follows: Lower asymptote Higher asymptote

Constructor Summary

Logistic(double k, double m, double b, double q, double a, double n)

Method Summary

UnivariateRealFunction	derivative() Returns the derivative of the function
double	value(double x) Compute the value of the function.

Methods inherited from class java.lang.Object

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

Constructor Detail

Logistic

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

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 UnivariateRealFunction

Parameters:

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

Returns:

the value of the function.

derivative

public UnivariateRealFunction derivative()

Returns the derivative of the function

Specified by:

derivative in interface DifferentiableUnivariateRealFunction

Returns:

the derivative function