An interface method for cumulative distribution function (CDF). Optionally provides a cumulative probability
of a value being between two values x1 and x2.
If called with 1 argument(x1) or if the value of second argument is empty string then
returns CDF value for x1. If called with two arguments, x1 and x2 then returns
a probability of a value being between x1 and x2.
abstract method pdf(x As %Double) as %Double [ Language = objectscript ]
An interface method for probability distribution function (PDF).
Returns PDF value for x.