Aim: Return quantiles for the Poisson distribution. Probability to get quantile or less is always >= 1 - epsilon. Probability to get 1+quantile or more is always < epsilon. Return lower quantile if epsilon < 0 such that probability to get quantile or more is always >= 1 - epsilon. Probability to get quantile-1 or less is always < epsilon.
The routine declaration is:
integer function quantilePoisson(mu, epsilon)
! mu : average value
! epsilon : probability level
real, intent(in) :: mu, epsilon