On Jan 18, 2007, at 11:10 AM, William James wrote:

> Ryan Davis wrote:
>> I wrote mine a bit different:
>>
>>    def prime(n)
>>      return false if n > 2 and n % 2 == 0
>>      max = sqrt(n)
>>      3.upto(max) do |i|
>>        return false if i % 2 != 0 and n % i == 0
>>      end
>>      return true
>>    end
>>
>>    optimize :prime
>

> You're saying that pure Ruby took less than 2 seconds?
> I don't see how that is possible.  On the faster of the two
> computers at my disposal your version ran in 207 seconds.

Yes, on my computer it ran in 2 seconds, but I didn't have the same  
driver as you did because I couldn't go into the bignum range. So I  
did the biggest you had an extra 20 times instead.