Package org.apache.commons.math3.distribution

Class UniformIntegerDistribution

    • Field Detail

      • serialVersionUID

        private static final long serialVersionUID
        Serializable version identifier.
        See Also:
        Constant Field Values

      • lower

        private final int lower
        Lower bound (inclusive) of this distribution.

      • upper

        private final int upper
        Upper bound (inclusive) of this distribution.

    • Constructor Detail

      • UniformIntegerDistribution

        public UniformIntegerDistribution​(int lower,
                                  int upper)
                           throws NumberIsTooLargeException
        Creates a new uniform integer distribution using the given lower and upper bounds (both inclusive).

        Note: this constructor will implicitly create an instance of Well19937c as random generator to be used for sampling only (see sample() and AbstractIntegerDistribution.sample(int)). In case no sampling is needed for the created distribution, it is advised to pass null as random generator via the appropriate constructors to avoid the additional initialisation overhead.

        Parameters:
        lower - Lower bound (inclusive) of this distribution.
        upper - Upper bound (inclusive) of this distribution.
        Throws:
        NumberIsTooLargeException - if lower >= upper.

      • UniformIntegerDistribution

        public UniformIntegerDistribution​(RandomGenerator rng,
                                  int lower,
                                  int upper)
                           throws NumberIsTooLargeException
        Creates a new uniform integer distribution using the given lower and upper bounds (both inclusive).
        Parameters:
        rng - Random number generator.
        lower - Lower bound (inclusive) of this distribution.
        upper - Upper bound (inclusive) of this distribution.
        Throws:
        NumberIsTooLargeException - if lower > upper.
        Since:
        3.1

    • Method Detail

      • probability

        public double probability​(int 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 (PMF) for the distribution.
        Parameters:
        x - the point at which the PMF is evaluated
        Returns:
        the value of the probability mass function at x

      • cumulativeProbability

        public double cumulativeProbability​(int 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 (cumulative) distribution function (CDF) for this distribution.
        Parameters:
        x - the point at which the CDF is evaluated
        Returns:
        the probability that a random variable with this distribution takes a value less than or equal to x

      • getNumericalMean

        public double getNumericalMean()
        Use this method to get the numerical value of the mean of this distribution. For lower bound lower and upper bound upper, the mean is 0.5 * (lower + upper).
        Returns:
        the mean or Double.NaN if it is not defined

      • getNumericalVariance

        public double getNumericalVariance()
        Use this method to get the numerical value of the variance of this distribution. For lower bound lower and upper bound upper, and n = upper - lower + 1, the variance is (n^2 - 1) / 12.
        Returns:
        the variance (possibly Double.POSITIVE_INFINITY or Double.NaN if it is not defined)

      • getSupportLowerBound

        public int getSupportLowerBound()
        Access the lower bound of the support. This method must return the same value as inverseCumulativeProbability(0). In other words, this method must return

        inf {x in Z | P(X <= x) > 0}.

        The lower bound of the support is equal to the lower bound parameter of the distribution.
        Returns:
        lower bound of the support

      • getSupportUpperBound

        public int getSupportUpperBound()
        Access the upper bound of the support. This method must return the same value as inverseCumulativeProbability(1). In other words, this method must return

        inf {x in R | P(X <= x) = 1}.

        The upper bound of the support is equal to the upper bound parameter of the distribution.
        Returns:
        upper bound of the support

      • isSupportConnected

        public boolean isSupportConnected()
        Use this method to get information about whether the support is connected, i.e. whether all integers between the lower and upper bound of the support are included in the support. The support of this distribution is connected.
        Returns:
        true