HyperGeometric (Colt 1.2.0 - API Specification)
Keywords: cern.jet.random.HyperGeometric class

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## cern.jet.random
Class HyperGeometric

    java.lang.Object
      cern.colt.PersistentObject
          cern.jet.random.AbstractDistribution
              cern.jet.random.AbstractDiscreteDistribution
                  cern.jet.random.HyperGeometric

All Implemented Interfaces:
  Cloneable, DoubleFunction, IntFunction, Serializable

public class HyperGeometric
extends AbstractDiscreteDistribution

HyperGeometric distribution; See the math definition The hypergeometric distribution with parameters `N`, `n` and `s` is the probability distribution of the random variable X, whose value is the number of successes in a sample of `n` items from a population of size `N` that has `s` 'success' items and `N - s` 'failure' items.

`p(k) = C(s,k) * C(N-s,n-k) / C(N,n)` where `C(a,b) = a! / (b! * (a-b)!)`.

valid for N >= 2, s,n <= N.

Instance methods operate on a user supplied uniform random number generator; they are unsynchronized.

Static methods operate on a default uniform random number generator; they are synchronized.

Implementation: High performance implementation. Patchwork Rejection/Inversion method.

This is a port of `hprsc.c` from the C-RAND / WIN-RAND library. C-RAND's implementation, in turn, is based upon

H. Zechner (1994): Efficient sampling from continuous and discrete unimodal distributions, Doctoral Dissertation, 156 pp., Technical University Graz, Austria.

Version:
  1.0, 09/24/99
See Also:
  Serialized Form

Field Summary

Fields inherited from class cern.colt.PersistentObject
`serialVersionUID`

Constructor Summary
`HyperGeometric(int N, int s, int n, RandomEngine randomGenerator)` Constructs a HyperGeometric distribution.

Method Summary
`int` | `nextInt()` Returns a random number from the distribution.
`int` | `nextInt(int N, int s, int n)` Returns a random number from the distribution; bypasses the internal state.
`double` | `pdf(int k)` Returns the probability distribution function.
`void` | `setState(int N, int s, int n)` Sets the parameters.
`static double` | `staticNextInt(int N, int M, int n)` Returns a random number from the distribution.
`String` | `toString()` Returns a String representation of the receiver.

Methods inherited from class cern.jet.random.AbstractDiscreteDistribution
`nextDouble`

Methods inherited from class cern.jet.random.AbstractDistribution
`apply, apply, clone, makeDefaultGenerator`

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Constructor Detail

### HyperGeometric

    public HyperGeometric(int N,
                          int s,
                          int n,
                          RandomEngine randomGenerator)

  Constructs a HyperGeometric distribution.

Method Detail

### nextInt

    public int nextInt()

  Returns a random number from the distribution.

  Specified by:
    `nextInt` in class `AbstractDiscreteDistribution`

### nextInt

    public int nextInt(int N,
                       int s,
                       int n)

  Returns a random number from the distribution; bypasses the internal state.

### pdf

    public double pdf(int k)

  Returns the probability distribution function.

### setState

    public void setState(int N,
                         int s,
                         int n)

  Sets the parameters.

### staticNextInt

    public static double staticNextInt(int N,
                                       int M,
                                       int n)

  Returns a random number from the distribution.

### toString

    public String toString()

  Returns a String representation of the receiver.

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