[calpaterson]

Hopefully you'd try another algorithm before you did that ;). Primality tests are one of the most highly understood and well documented areas of CS - trial division has been obsolete since, what, 1640?

[btilly]

... trial division has been obsolete since, what, 1640?

Longer than that. The sieve of Eratosthenes is attributed to Eratosthenes, who lived from 276 BC to 195 BC.

[calpaterson]

Hah, this exact thing occurred to me lying in bed last night :)