Package org.apache.commons.math.distribution

Class BinomialDistributionImpl

java.lang.Object
org.apache.commons.math.distribution.AbstractDistribution
org.apache.commons.math.distribution.AbstractIntegerDistribution
org.apache.commons.math.distribution.BinomialDistributionImpl
All Implemented Interfaces:
Serializable, BinomialDistribution, DiscreteDistribution, Distribution, IntegerDistribution
public class BinomialDistributionImpl extends AbstractIntegerDistribution implements BinomialDistribution, Serializable
The default implementation of BinomialDistribution.
See Also:

  • Constructor Details

    • BinomialDistributionImpl

      public BinomialDistributionImpl(int trials, double p)
      Create a binomial distribution with the given number of trials and probability of success.
      Parameters:
      trials - the number of trials.
      p - the probability of success.

  • Method Details

    • getNumberOfTrials

      public int getNumberOfTrials()
      Access the number of trials for this distribution.
      Specified by:
      getNumberOfTrials in interface BinomialDistribution
      Returns:
      the number of trials.

    • getProbabilityOfSuccess

      public double getProbabilityOfSuccess()
      Access the probability of success for this distribution.
      Specified by:
      getProbabilityOfSuccess in interface BinomialDistribution
      Returns:
      the probability of success.

    • setNumberOfTrials

      @Deprecated public void setNumberOfTrials(int trials)
      Deprecated.
      as of 2.1 (class will become immutable in 3.0)
      Change the number of trials for this distribution.
      Specified by:
      setNumberOfTrials in interface BinomialDistribution
      Parameters:
      trials - the new number of trials.
      Throws:
      IllegalArgumentException - if trials is not a valid number of trials.

    • 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 BinomialDistribution
      Parameters:
      p - the new probability of success.
      Throws:
      IllegalArgumentException - if p is not a valid probability.

    • 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) invalid input: '<'= p
      Throws:
      MathException - if the inverse cumulative probability can not be computed due to convergence or other numerical errors.
      IllegalArgumentException - if p invalid input: '<' 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 number of trials and probability parameter.
      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 the number of trials.
      Returns:
      upper bound of the support (equal to number of trials)
      Since:
      2.2

    • getNumericalMean

      public double getNumericalMean()
      Returns the mean. For n number of trials and probability parameter p, the mean is n * p
      Returns:
      the mean
      Since:
      2.2

    • getNumericalVariance

      public double getNumericalVariance()
      Returns the variance. For n number of trials and probability parameter p, the variance is n * p * (1 - p)
      Returns:
      the variance
      Since:
      2.2