sim.util.distribution
Class NegativeBinomial

java.lang.Object
  sim.util.distribution.AbstractDistribution
      sim.util.distribution.AbstractDiscreteDistribution
          sim.util.distribution.NegativeBinomial

All Implemented Interfaces:

java.io.Serializable

public class NegativeBinomial
extends AbstractDiscreteDistribution

Negative Binomial distribution; See the math definition.

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. Compound method.

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

J.H. Ahrens, U. Dieter (1974): Computer methods for sampling from gamma, beta, Poisson and binomial distributions, Computing 12, 223--246.

See Also:

Serialized Form

Field Summary

protected Gamma	gamma
protected int	n
protected double	p
protected Poisson	poisson

Fields inherited from class sim.util.distribution.AbstractDistribution

randomGenerator

Constructor Summary

NegativeBinomial(int n, double p, MersenneTwisterFast randomGenerator)
Constructs a Negative Binomial distribution.

Method Summary

double	cdf(int k) Returns the cumulative distribution function.
int	nextInt() Returns a random number from the distribution.
int	nextInt(int n, double p) Returns a random number from the distribution; bypasses the internal state.
double	pdf(int k) Returns the probability distribution function.
void	setNandP(int n, double p) Sets the parameters number of trials and the probability of success.
java.lang.String	toString() Returns a String representation of the receiver.

Methods inherited from class sim.util.distribution.AbstractDiscreteDistribution

nextDouble

Methods inherited from class sim.util.distribution.AbstractDistribution

apply, apply, getRandomGenerator, setRandomGenerator

Methods inherited from class java.lang.Object

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

Field Detail

n

protected int n

p

protected double p

gamma

protected Gamma gamma

poisson

protected Poisson poisson

Constructor Detail

NegativeBinomial

public NegativeBinomial(int n,
                        double p,
                        MersenneTwisterFast randomGenerator)

Constructs a Negative Binomial distribution. Example: n=1, p=0.5.

Parameters:

n - the number of trials.

p - the probability of success.

randomGenerator - a uniform random number generator.

Method Detail

cdf

public double cdf(int k)

Returns the cumulative distribution function.

nextInt

public int nextInt()

Returns a random number from the distribution.

Specified by:

nextInt in class AbstractDiscreteDistribution

nextInt

public int nextInt(int n,
                   double p)

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

pdf

public double pdf(int k)

Returns the probability distribution function.

setNandP

public void setNandP(int n,
                     double p)

Sets the parameters number of trials and the probability of success.

Parameters:

n - the number of trials

p - the probability of success.

toString

public java.lang.String toString()

Returns a String representation of the receiver.

Overrides:

toString in class java.lang.Object