org.apache.commons.math.distribution
Class PascalDistributionImpl

java.lang.Object
  org.apache.commons.math.distribution.AbstractDistribution
      org.apache.commons.math.distribution.AbstractIntegerDistribution
          org.apache.commons.math.distribution.PascalDistributionImpl

All Implemented Interfaces:

Serializable, DiscreteDistribution, Distribution, IntegerDistribution, PascalDistribution

public class PascalDistributionImpl
extends AbstractIntegerDistribution
implements PascalDistribution, Serializable

The default implementation of PascalDistribution.

Since:

1.2

Version:

$Revision: 1054524 $ $Date: 2011-01-03 05:59:18 +0100 (lun. 03 janv. 2011) $

See Also:

Serialized Form

Field Summary

Fields inherited from class org.apache.commons.math.distribution.AbstractIntegerDistribution

randomData

Constructor Summary

PascalDistributionImpl(int r, double p)
Create a Pascal distribution with the given number of trials and probability of success.

Method Summary

double	cumulativeProbability(int x) For this distribution, X, this method returns P(X ≤ x).
protected int	getDomainLowerBound(double p) Access the domain value lower bound, based on p, used to bracket a PDF root.
protected int	getDomainUpperBound(double p) Access the domain value upper bound, based on p, used to bracket a PDF root.
int	getNumberOfSuccesses() Access the number of successes for this distribution.
double	getNumericalMean() Returns the mean.
double	getNumericalVariance() Returns the variance.
double	getProbabilityOfSuccess() Access the probability of success for this distribution.
int	getSupportLowerBound() Returns the lower bound of the support for the distribution.
int	getSupportUpperBound() Returns the upper bound of the support for the distribution.
int	inverseCumulativeProbability(double p) For this distribution, X, this method returns the largest x, such that P(X ≤ x) ≤ p.
double	probability(int x) For this distribution, X, this method returns P(X = x).
void	setNumberOfSuccesses(int successes) Deprecated. as of 2.1 (class will become immutable in 3.0)
void	setProbabilityOfSuccess(double p) Deprecated. as of 2.1 (class will become immutable in 3.0)

Methods inherited from class org.apache.commons.math.distribution.AbstractIntegerDistribution

cumulativeProbability, cumulativeProbability, cumulativeProbability, isSupportLowerBoundInclusive, isSupportUpperBoundInclusive, probability, reseedRandomGenerator, sample, sample

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.commons.math.distribution.IntegerDistribution

cumulativeProbability

Methods inherited from interface org.apache.commons.math.distribution.DiscreteDistribution

probability

Methods inherited from interface org.apache.commons.math.distribution.Distribution

cumulativeProbability, cumulativeProbability

Constructor Detail

PascalDistributionImpl

public PascalDistributionImpl(int r,
                              double p)

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

Parameters:

r - the number of successes

p - the probability of success

Method Detail

getNumberOfSuccesses

public int getNumberOfSuccesses()

Access the number of successes for this distribution.

Specified by:

getNumberOfSuccesses in interface PascalDistribution

Returns:

the number of successes

getProbabilityOfSuccess

public double getProbabilityOfSuccess()

Access the probability of success for this distribution.

Specified by:

getProbabilityOfSuccess in interface PascalDistribution

Returns:

the probability of success

setNumberOfSuccesses

@Deprecated
public void setNumberOfSuccesses(int successes)

Deprecated. as of 2.1 (class will become immutable in 3.0)

Change the number of successes for this distribution.

Specified by:

setNumberOfSuccesses in interface PascalDistribution

Parameters:

successes - the new number of successes

Throws:

IllegalArgumentException - if successes is not positive.

setProbabilityOfSuccess

@Deprecated
public void setProbabilityOfSuccess(double p)

Deprecated. as of 2.1 (class will become immutable in 3.0)

Change the probability of success for this distribution.

Specified by:

setProbabilityOfSuccess in interface PascalDistribution

Parameters:

p - the new probability of success

Throws:

IllegalArgumentException - if p is not a valid probability.

getDomainLowerBound

protected int getDomainLowerBound(double p)

Access the domain value lower bound, based on p, used to bracket a PDF root.

Specified by:

getDomainLowerBound in class AbstractIntegerDistribution

Parameters:

p - the desired probability for the critical value

Returns:

domain value lower bound, i.e. P(X < lower bound) < p

getDomainUpperBound

protected int getDomainUpperBound(double p)

Access the domain value upper bound, based on p, used to bracket a PDF root.

Specified by:

getDomainUpperBound in class AbstractIntegerDistribution

Parameters:

p - the desired probability for the critical value

Returns:

domain value upper bound, i.e. P(X < upper bound) > p

cumulativeProbability

public double cumulativeProbability(int x)
                             throws MathException

For this distribution, X, this method returns P(X ≤ x).

Specified by:

cumulativeProbability in interface IntegerDistribution

Specified by:

cumulativeProbability in class AbstractIntegerDistribution

Parameters:

x - the value at which the PDF is evaluated

Returns:

PDF for this distribution

Throws:

MathException - if the cumulative probability can not be computed due to convergence or other numerical errors

probability

public double probability(int x)

For this distribution, X, this method returns P(X = x).

Specified by:

probability in interface IntegerDistribution

Parameters:

x - the value at which the PMF is evaluated

Returns:

PMF for this distribution

inverseCumulativeProbability

public int inverseCumulativeProbability(double p)
                                 throws MathException

For this distribution, X, this method returns the largest x, such that P(X ≤ x) ≤ p.

Returns -1 for p=0 and Integer.MAX_VALUE for p=1.

Specified by:

inverseCumulativeProbability in interface IntegerDistribution

Overrides:

inverseCumulativeProbability in class AbstractIntegerDistribution

Parameters:

p - the desired probability

Returns:

the largest x such that P(X ≤ x) <= p

Throws:

MathException - if the inverse cumulative probability can not be computed due to convergence or other numerical errors.

IllegalArgumentException - if p < 0 or p > 1

getSupportLowerBound

public int getSupportLowerBound()

Returns the lower bound of the support for the distribution. The lower bound of the support is always 0 no matter the parameters.

Returns:

lower bound of the support (always 0)

Since:

2.2

getSupportUpperBound

public int getSupportUpperBound()

Returns the upper bound of the support for the distribution. The upper bound of the support is always positive infinity no matter the parameters. Positive infinity is represented by Integer.MAX_VALUE together with AbstractIntegerDistribution.isSupportUpperBoundInclusive() being false

Returns:

upper bound of the support (always Integer.MAX_VALUE for positive infinity)

Since:

2.2

getNumericalMean

public double getNumericalMean()

Returns the mean. For number of successes r and probability of success p, the mean is ( r * p ) / ( 1 - p )

Returns:

the mean

Since:

2.2

getNumericalVariance

public double getNumericalVariance()

Returns the variance. For number of successes r and probability of success p, the mean is ( r * p ) / ( 1 - p )^2

Returns:

the variance

Since:

2.2