de.lmu.ifi.dbs.elki.data.synthetic.bymodel.distribution
Class NormalDistribution

java.lang.Object
  de.lmu.ifi.dbs.elki.data.synthetic.bymodel.distribution.NormalDistribution

All Implemented Interfaces:

Distribution

public final class NormalDistribution
extends Object
implements Distribution

Simple generator for a Gaussian = Normal Distribution

Author:

Erich Schubert

Field Summary

private double	mean Mean value for the generator
private Random	random The random generator.
private double	stddev Standard deviation

Constructor Summary

NormalDistribution(double mean, double stddev, Random random)
Constructor for Gaussian generator

Method Summary

double	explain(double val) Return the PDF of the generators distribution
double	generate() Generate a random value with the generators parameters
double	getMean()
double	getStddev()
private static double	phi(double x) Standardized Gaussian PDF
static double	phi(double x, double mu, double sigma) Gaussian distribution PDF
String	toString() Simple toString explaining the distribution parameters.

Methods inherited from class java.lang.Object

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

Field Detail

mean

private double mean

Mean value for the generator

stddev

private double stddev

Standard deviation

random

private Random random

The random generator.

Constructor Detail

NormalDistribution

public NormalDistribution(double mean,
                          double stddev,
                          Random random)

Constructor for Gaussian generator

Parameters:

mean - Mean

stddev - Standard Deviation

random - Random generator

Method Detail

phi

private static double phi(double x)

Standardized Gaussian PDF

Parameters:

x - query value

Returns:

probability density

phi

public static double phi(double x,
                         double mu,
                         double sigma)

Gaussian distribution PDF

Parameters:

x - query value

mu - mean

sigma - standard distribution

Returns:

probability density

explain

public double explain(double val)

Return the PDF of the generators distribution

Specified by:

explain in interface Distribution

Parameters:

val - existing value

Returns:

distribution density

generate

public double generate()

Generate a random value with the generators parameters

Specified by:

generate in interface Distribution

Returns:

new generated value

toString

public String toString()

Simple toString explaining the distribution parameters. Used in producing a model description.

Specified by:

toString in interface Distribution

Overrides:

toString in class Object

Returns:

description

getMean

public double getMean()

Returns:

the mean

getStddev

public double getStddev()

Returns:

the standard deviation