Data.Random.Distribution.Poisson

The probability of getting exactly k successes is given by the probability mass function:

f(k;\lambda) = \Pr(X = k) = \frac{\lambda^k e^{-\lambda}}{k!}

Note that in integralPoissonPDF the parameter of the mass function are given first and the range of the random variable distributed according to the Poisson distribution is given last. That is, f(2;0.5) is calculated by integralPoissonPDF 0.5 2.