Package org.apache.commons.math.optimization.fitting

Class GaussianFunction

java.lang.Object

org.apache.commons.math.optimization.fitting.GaussianFunction

All Implemented Interfaces:

java.io.Serializable, DifferentiableUnivariateRealFunction, UnivariateRealFunction

public class GaussianFunction
extends java.lang.Object
implements DifferentiableUnivariateRealFunction, java.io.Serializable

A Gaussian function. Specifically:

f(x) = a + b*exp(-((x - c)^2 / (2*d^2)))

Notation key:

• x^n: x raised to the power of n
• exp(x): e^x

References:

• Wikipedia: Gaussian function

Since:

2.2

See Also:

GaussianDerivativeFunction, ParametricGaussianFunction, Serialized Form

Constructor Summary

Constructors

Constructor	Description
GaussianFunction(double[] parameters)	Constructs an instance with the specified parameters.
GaussianFunction(double a, double b, double c, double d)	Constructs an instance with the specified parameters.

Method Summary

Modifier and Type	Method	Description
UnivariateRealFunction	derivative()	Returns the derivative of the function
double	getA()	Gets a parameter value.
double	getB()	Gets b parameter value.
double	getC()	Gets c parameter value.
double	getD()	Gets d parameter value.
double	value(double x)	Compute the value for the function.

Methods inherited from class java.lang.Object

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

Constructor Detail

GaussianFunction

public GaussianFunction(double a,
                        double b,
                        double c,
                        double d)

Constructs an instance with the specified parameters.

Parameters:

a - a parameter value

b - b parameter value

c - c parameter value

d - d parameter value

Throws:

java.lang.IllegalArgumentException - if d is 0

GaussianFunction

public GaussianFunction(double[] parameters)

Constructs an instance with the specified parameters.

Parameters:

parameters - a, b, c, and d parameter values

Throws:

java.lang.IllegalArgumentException - if parameters is null, parameters length is not 4, or if parameters[3] is 0

Method Detail

derivative

public UnivariateRealFunction derivative()

Returns the derivative of the function

Specified by:

derivative in interface DifferentiableUnivariateRealFunction

Returns:

the derivative function

value

public double value(double x)

Compute the value for the function.

Specified by:

value in interface UnivariateRealFunction

Parameters:

x - the point for which the function value should be computed

Returns:

the value

getA

public double getA()

Gets a parameter value.

Returns:

a parameter value

getB

public double getB()

Gets b parameter value.

Returns:

b parameter value

getC

public double getC()

Gets c parameter value.

Returns:

c parameter value

getD

public double getD()

Gets d parameter value.

Returns:

d parameter value