[NUMBERS-170] RegularizedBeta function to detect edge cases

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 1.0
• Fix Version/s: 1.1
• Component/s: gamma
• Assignee: Unassigned
• Reporter: Alex Herbert
• Created: 10/Oct/21 13:29
• Updated: 01/Nov/22 11:00
• Resolved: 10/Oct/21 15:45

Description

The Regularized incomplete beta function Has the following properties:

I(0; a, b) = 0
I(1; a, b) = 1
I(x; a, 1) = x^a
I(x, 1, b) = 1 - (1-x)^b

Currently this test fails:

Assertions.assertEquals(1.0, RegularizedBeta.value(1.0, 1e17, 0.5));

The function presently ignores the x=0 and x=1 case which evaluate with infinities due to the use of log( x ) and log(1-x).

The function should be corrected to handle edge cases.

Issue Links

• relates to: STATISTICS-25 T Distribution Inverse Cumulative Probability Function gives the Wrong Answer