Class AbstractIntegerDistribution

    • Constructor Detail

      • AbstractIntegerDistribution

        public AbstractIntegerDistribution()
        Empty constructor.

        This constructor is not strictly necessary, but it prevents spurious javadoc warnings with JDK 18 and later.

    • Method Detail

      • probability

        public double probability​(int x0,
                                  int x1)
                           throws MathIllegalArgumentException
        For a random variable X whose values are distributed according to this distribution, this method returns P(x0 < X <= x1). The default implementation uses the identity

        P(x0 < X <= x1) = P(X <= x1) - P(X <= x0)

        Specified by:
        probability in interface IntegerDistribution
        x0 - the exclusive lower bound
        x1 - the inclusive upper bound
        the probability that a random variable with this distribution will take a value between x0 and x1, excluding the lower and including the upper endpoint
        MathIllegalArgumentException - if x0 > x1
      • solveInverseCumulativeProbability

        protected int solveInverseCumulativeProbability​(double p,
                                                        int lower,
                                                        int upper)
        This is a utility function used by inverseCumulativeProbability(double). It assumes 0 < p < 1 and that the inverse cumulative probability lies in the bracket (lower, upper]. The implementation does simple bisection to find the smallest p-quantile inf{x in Z | P(X<=x) >= p}.
        p - the cumulative probability
        lower - a value satisfying cumulativeProbability(lower) < p
        upper - a value satisfying p <= cumulativeProbability(upper)
        the smallest p-quantile of this distribution
      • logProbability

        public double logProbability​(int x)
        For a random variable X whose values are distributed according to this distribution, this method returns log(P(X = x)), where log is the natural logarithm. In other words, this method represents the logarithm of the probability mass function (PMF) for the distribution. Note that due to the floating point precision and under/overflow issues, this method will for some distributions be more precise and faster than computing the logarithm of IntegerDistribution.probability(int).

        The default implementation simply computes the logarithm of probability(x).

        Specified by:
        logProbability in interface IntegerDistribution
        x - the point at which the PMF is evaluated
        the logarithm of the value of the probability mass function at x