pal.statistics
Class ChiSquareDistribution

java.lang.Object
  pal.statistics.GammaDistribution
      pal.statistics.ChiSquareDistribution

public class ChiSquareDistribution
extends GammaDistribution

chi-square distribution (distribution of sum of squares of n uniform random variables) (Parameter: n; mean: n; variance: 2*n) The chi-square distribution is a special case of the Gamma distribution (shape parameter = n/2.0, scale = 2.0).

Version:

$Id: ChiSquareDistribution.java,v 1.2 2001/07/13 14:39:13 korbinian Exp $

Author:

Korbinian Strimmer

Constructor Summary

ChiSquareDistribution()

Method Summary

static double	cdf(double x, double n) cumulative density function of the chi-square distribution
static double	mean(double n) mean of the chi-square distribution
static double	pdf(double x, double n) probability density function of the chi-square distribution
static double	quantile(double y, double n) quantile (inverse cumulative density function) of the chi-square distribution
static double	variance(double n) variance of the chi-square distribution

Methods inherited from class pal.statistics.GammaDistribution

cdf, mean, pdf, quantile, variance

Methods inherited from class java.lang.Object

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

Constructor Detail

ChiSquareDistribution

public ChiSquareDistribution()

Method Detail

pdf

public static double pdf(double x,
                         double n)

probability density function of the chi-square distribution

Parameters:

x - argument

n - degrees of freedom

Returns:

pdf value

cdf

public static double cdf(double x,
                         double n)

cumulative density function of the chi-square distribution

Parameters:

x - argument

n - degrees of freedom

Returns:

cdf value

quantile

public static double quantile(double y,
                              double n)

quantile (inverse cumulative density function) of the chi-square distribution

Parameters:

x - argument

n - degrees of freedom

Returns:

icdf value

mean

public static double mean(double n)

mean of the chi-square distribution

Parameters:

n - degrees of freedom

Returns:

mean

variance

public static double variance(double n)

variance of the chi-square distribution

Parameters:

n - degrees of freedom

Returns:

variance