Larger Integers

[drij]

I was working my way through the problems on Project Euler when I encountered an issue with problem 3.

The problem is: "What is the largest prime factor of 600851475143?"

I wrote a nice little prime-checking function:

Turing:

fcn isPrime (maybePrime : int) : boolean     var hasNoFactors : boolean := true     if maybePrime = 1 or maybePrime = 2 then         result true     end if     for maybeFactor : 2 .. floor (sqrt (maybePrime))         if maybePrime mod maybeFactor = 0 then             hasNoFactors := false         end if     end for     result hasNoFactors end isPrime

After I wrote this, I couldn't figure out how to deal with the size of the number 600851475143.

My question is, is it possible to work with large numbers such as this in turing?

[OneOffDriveByPoster]

Yes, the double-precision floating point can represent at least this, and all the integers >= 0 below it exactly.

[Saad]

But it should be known that it can not represent accurately be represented. Unfortunately Turing has no default way of handling them with full accuray. You could make your own though.

[Insectoid]

does Turing not support 'long' variables?

[Saad]

None to my knowledge

[[Gandalf]]

Nope, it doesn't. float is as much precision as you can get.

[drij]

Ok then. Thanks for all your replies.

[[Gandalf]]

If you're looking to get further ahead in Euler, and are willing to learn a new language that's not too difficult, I'd recommend Ruby or Python. Both, AFAIK, support arbitrarily long integers by default.