[MAHOUT-187] RandomUtils>>isNotPrime throws IllegalArgumentException when argument is less than 2.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.1
• Fix Version/s: 0.2
• Assignee: Sean R. Owen
• Reporter: Emerson Murphy-HIll
• Due: 16/Oct/09
• Created: 16/Oct/09 15:43
• Updated: 18/Nov/09 14:05
• Resolved: 19/Oct/09 14:44

Description

I was using a FastMap, which happened to be empty, and rehash() was called. Rehash eventually calls isNotPrime where n=1, which throws an illegal argument exception:

public static boolean isNotPrime(int n) {
if (n < 2)

{ throw new IllegalArgumentException(); }

It seems to me anything less than two is not prime. Thus, I suggest:

public static boolean isNotPrime(int n) {
if (n < 2)

{ return true; }