AhrensDieterMarsagliaTsangGammaSampler (VirtualDataSet API)

java.lang.Object
- org.apache.commons.rng.sampling.distribution.SamplerBase
- - org.apache.commons.rng.sampling.distribution.AhrensDieterMarsagliaTsangGammaSampler

All Implemented Interfaces:

ContinuousSampler
```
public class AhrensDieterMarsagliaTsangGammaSampler
extends SamplerBase
implements ContinuousSampler
```
Sampling from the Gamma distribution.
- For 0 < theta < 1:
  Ahrens, J. H. and Dieter, U., Computer methods for sampling from gamma, beta, Poisson and binomial distributions, Computing, 12, 223-246, 1974.
- For theta >= 1:
  Marsaglia and Tsang, A Simple Method for Generating Gamma Variables. ACM Transactions on Mathematical Software, Volume 26 Issue 3, September, 2000.
Sampling uses:
- UniformRandomProvider.nextDouble() (both algorithms)
- UniformRandomProvider.nextLong() (only for theta >= 1)
Since:

1.0

Constructor Summary

Constructors
Constructor	Description
`AhrensDieterMarsagliaTsangGammaSampler(UniformRandomProvider rng, double alpha, double theta)`

Method Summary

Modifier and Type Method Description

double sample()
Creates a sample.

java.lang.String toString()
- Methods inherited from class org.apache.commons.rng.sampling.distribution.SamplerBase
  nextDouble, nextInt, nextInt, nextLong
- Methods inherited from class java.lang.Object
  clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - AhrensDieterMarsagliaTsangGammaSampler
```
public AhrensDieterMarsagliaTsangGammaSampler(UniformRandomProvider rng,
                                              double alpha,
                                              double theta)
```
    Parameters:
    
    rng - Generator of uniformly distributed random numbers.
    
    alpha - Alpha shape parameter of the distribution.
    
    theta - Theta scale parameter of the distribution.
    
    Throws:
    
    java.lang.IllegalArgumentException - if alpha <= 0 or theta <= 0
- Method Detail
  - sample
```
public double sample()
```
    Creates a sample.
    
    Specified by:
    
    sample in interface ContinuousSampler
    
    Returns:
    
    a sample.
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class SamplerBase