Forgive me if this has been answered, I have look all around and can’t

seem

to find an answer. I am trying to implement the Fermat primality test (

http://en.wikipedia.org/wiki/Fermat_primality_test ) in Ruby. The

problem is

everytime ruby does the a^(n-1) computation, it seems to stumble on

numbers

like 1000 (so its doing a^999). I have set both a and n to fixnums, and

according to everything I have read, it should switch to bignum if the

result is too big. But it doesn’t seem to do that, it just seems to spit

out

infinity. Any ideas? I used the latest one click installer to install

Ruby.

Ethan