[MATH-1136] BinomialDistribution deals with degenerate cases incorrectly

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.3
• Fix Version/s: 3.4
• Labels: bug patch
• Assignee: Unassigned
• Reporter: Aleksei Dievskii
• Created: 11/Jul/14 11:30
• Updated: 26/Dec/14 19:50
• Resolved: 11/Jul/14 19:23

Description

The following calculation returns false results:

new BinomialDistribution(0, 0.01).logProbability(0)

It evaluates to Double.NaN when it should be 0 (cf., for example, "dbinom(0, 0, 0.01, log=T)" in R).

I attach a patch dealing with the problem. The patch also adds a test for this bug.