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

Constructors
Constructor Description

ChiSquareDistribution()

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method	Description
`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