jhplot.math.num.pdf
Class NegativeBinomial

java.lang.Object
  jhplot.math.num.pdf.DiscreteDistribution
      jhplot.math.num.pdf.NegativeBinomial

All Implemented Interfaces:

Distribution

public class NegativeBinomial
extends DiscreteDistribution

The Negative Binomial distribution.

References:

1. Eric W. Weisstein. "Negative Binomial Distribution." From MathWorld--A Wolfram Web Resource. http://mathworld.wolfram.com/NegativeBinomial.html

Since:

1.2

Version:

$Revision: 1.2 $ $Date: 2007/10/25 04:44:10 $

Constructor Summary

NegativeBinomial()
Default constructor.

NegativeBinomial(int r, double p)
Create a distribution with the given number of successes and probability of success.

Method Summary

double	cumulativeProbability(int x) The CDF for this distribution.
double	getMean() Get mean value.
int	getNumberOfSuccesses() Access the number of successes.
double	getProbabilityOfSuccess() Access probability of success.
double	getVariance() Get mean value.
int	inverseCumulativeProbability(double p) The inverse CDF for this distribution.
double	probability(int x) The PMF for this distribution.
void	setNumberOfSuccesses(int r) Modify the number of successes.
void	setProbabilityOfSuccess(double p) Modify probability of success.

Methods inherited from class java.lang.Object

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

Constructor Detail

NegativeBinomial

public NegativeBinomial()

Default constructor. Number of successes is set to one and probability of success is set to 0.5.

NegativeBinomial

public NegativeBinomial(int r,
                        double p)

Create a distribution with the given number of successes and probability of success.

Parameters:

r - the number of successes.

p - the probability of success.

Method Detail

cumulativeProbability

public double cumulativeProbability(int x)
                             throws NumericException

The CDF for this distribution. This method returns P(X ≤ x).

Specified by:

cumulativeProbability in class DiscreteDistribution

Parameters:

x - the value at which the CDF is evaluated.

Returns:

CDF for this distribution.

Throws:

NumericException - if the cumulative probability can not be computed.

getNumberOfSuccesses

public int getNumberOfSuccesses()

Access the number of successes.

Returns:

the number of successes.

getProbabilityOfSuccess

public double getProbabilityOfSuccess()

Access probability of success.

Returns:

the probability of success.

inverseCumulativeProbability

public int inverseCumulativeProbability(double p)
                                 throws NumericException

The inverse CDF for this distribution. This method returns the largest x such that, P(X ≤ x) ≤ p. The return value must also satisfy P(X ≥ x) &ge 1 - p.

Specified by:

inverseCumulativeProbability in class DiscreteDistribution

Parameters:

p - the cumulative probability.

Returns:

x

Throws:

NumericException - if the inverse cumulative probability can not be computed.

probability

public double probability(int x)

The PMF for this distribution. This method returns P(X = x).

Specified by:

probability in class DiscreteDistribution

Parameters:

x - the value at which the probability is evaluated.

Returns:

PMF for this distribution.

setNumberOfSuccesses

public void setNumberOfSuccesses(int r)

Modify the number of successes.

Parameters:

r - the new number of successes value.

getMean

public double getMean()

Get mean value. Calculated as numberOfSuccesses * probabilityOfSuccess / (1-probabilityOfSuccess)

Parameters:

r - the new number of successes value.

getVariance

public double getVariance()

Get mean value. Calculated as numberOfSuccesses * probabilityOfSuccess / (1-probabilityOfSuccess)**2

Parameters:

r - the new number of successes value.

setProbabilityOfSuccess

public void setProbabilityOfSuccess(double p)

Modify probability of success.

Parameters:

p - the new probability of success value.