org.apache.commons.math.distribution
Interface PoissonDistribution

All Superinterfaces:
DiscreteDistribution, Distribution, IntegerDistribution
All Known Implementing Classes:
PoissonDistributionImpl

public interface PoissonDistribution
extends IntegerDistribution

Interface representing the Poisson Distribution.

References:

Version:
$Revision: 670469 $ $Date: 2008-06-23 04:01:38 -0400 (Mon, 23 Jun 2008) $

Method Summary
 double getMean()
          Get the mean for the distribution.
 double normalApproximateProbability(int x)
          Calculates the Poisson distribution function using a normal approximation.
 void setMean(double p)
          Set the mean for the distribution.
 
Methods inherited from interface org.apache.commons.math.distribution.IntegerDistribution
cumulativeProbability, cumulativeProbability, inverseCumulativeProbability, probability
 
Methods inherited from interface org.apache.commons.math.distribution.DiscreteDistribution
probability
 
Methods inherited from interface org.apache.commons.math.distribution.Distribution
cumulativeProbability, cumulativeProbability
 

Method Detail

getMean

double getMean()
Get the mean for the distribution.

Returns:
the mean for the distribution.

setMean

void setMean(double p)
Set the mean for the distribution. The parameter value must be positive; otherwise an IllegalArgument is thrown.

Parameters:
p - the mean
Throws:
java.lang.IllegalArgumentException - if p ≤ 0

normalApproximateProbability

double normalApproximateProbability(int x)
                                    throws MathException
Calculates the Poisson distribution function using a normal approximation.

Parameters:
x - the upper bound, inclusive
Returns:
the distribution function value calculated using a normal approximation
Throws:
MathException - if an error occurs computing the normal approximation


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