org.apache.commons.math.distribution
Class AbstractIntegerDistribution

java.lang.Object
  extended by org.apache.commons.math.distribution.AbstractDistribution
      extended by org.apache.commons.math.distribution.AbstractIntegerDistribution
All Implemented Interfaces:
java.io.Serializable, DiscreteDistribution, Distribution, IntegerDistribution
Direct Known Subclasses:
BinomialDistributionImpl, HypergeometricDistributionImpl, PoissonDistributionImpl

public abstract class AbstractIntegerDistribution
extends AbstractDistribution
implements IntegerDistribution, java.io.Serializable

Base class for integer-valued discrete distributions. Default implementations are provided for some of the methods that do not vary from distribution to distribution.

See Also:
Serialized Form

Method Summary
 double cumulativeProbability(double x)
          For a random variable X whose values are distributed according to this distribution, this method returns P(X ≤ x).
abstract  double cumulativeProbability(int x)
          For a random variable X whose values are distributed according to this distribution, this method returns P(X ≤ x).
 double cumulativeProbability(int x0, int x1)
          For a random variable X whose values are distributed according to this distribution, this method returns P(x0 ≤ X ≤ x1).
 int inverseCumulativeProbability(double p)
          For a random variable X whose values are distributed according to this distribution, this method returns the largest x, such that P(X ≤ x) ≤ p.
 double probability(double x)
          For a random variable X whose values are distributed according to this distribution, this method returns P(X = x).
 
Methods inherited from class org.apache.commons.math.distribution.AbstractDistribution
cumulativeProbability
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface org.apache.commons.math.distribution.IntegerDistribution
probability
 
Methods inherited from interface org.apache.commons.math.distribution.Distribution
cumulativeProbability
 

Method Detail

cumulativeProbability

public double cumulativeProbability(double x)
                             throws MathException
For a random variable X whose values are distributed according to this distribution, this method returns P(X ≤ x). In other words, this method represents the (cumulative) distribution function, or CDF, for this distribution.

If x does not represent an integer value, the CDF is evaluated at the greatest integer less than x.

Specified by:
cumulativeProbability in interface Distribution
Parameters:
x - the value at which the distribution function is evaluated.
Returns:
cumulative probability that a random variable with this distribution takes a value less than or equal to x
Throws:
MathException - if the cumulative probability can not be computed due to convergence or other numerical errors.

cumulativeProbability

public abstract double cumulativeProbability(int x)
                                      throws MathException
For a random variable X whose values are distributed according to this distribution, this method returns P(X ≤ x). In other words, this method represents the probability distribution function, or PDF, for this distribution.

Specified by:
cumulativeProbability in interface IntegerDistribution
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(double x)
For a random variable X whose values are distributed according to this distribution, this method returns P(X = x). In other words, this method represents the probability mass function, or PMF, for the distribution.

If x does not represent an integer value, 0 is returned.

Specified by:
probability in interface DiscreteDistribution
Parameters:
x - the value at which the probability density function is evaluated
Returns:
the value of the probability density function at x

cumulativeProbability

public double cumulativeProbability(int x0,
                                    int x1)
                             throws MathException
For a random variable X whose values are distributed according to this distribution, this method returns P(x0 ≤ X ≤ x1).

Specified by:
cumulativeProbability in interface IntegerDistribution
Parameters:
x0 - the inclusive, lower bound
x1 - the inclusive, upper bound
Returns:
the cumulative probability.
Throws:
MathException - if the cumulative probability can not be computed due to convergence or other numerical errors.
java.lang.IllegalArgumentException - if x0 > x1

inverseCumulativeProbability

public int inverseCumulativeProbability(double p)
                                 throws MathException
For a random variable X whose values are distributed according to this distribution, this method returns the largest x, such that P(X ≤ x) ≤ p.

Specified by:
inverseCumulativeProbability in interface IntegerDistribution
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.
java.lang.IllegalArgumentException - if p < 0 or p > 1


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