Task

Write a boolean function that tells whether a given integer is prime.



Remember that   1   and all non-positive numbers are not prime.

Use trial division.

Even numbers greater than   2   may be eliminated right away.

A loop from   3   to   √ n    will suffice,   but other loops are allowed.



Related tasks

   count in factors
   prime decomposition
   AKS test for primes
   factors of an integer
   Sieve of Eratosthenes
   factors of a Mersenne number
   trial factoring of a Mersenne number
   partition an integer X into N primes
   sequence of primes by Trial Division


on isPrime(n)
    if (n < 3) then return (n is 2)
    if (n mod 2 is 0) then return false
    repeat with i from 3 to (n ^ 0.5) div 1 by 2
        if (n mod i is 0) then return false
    end repeat
 
    return true
end isPrime
 
-- Test code:
set output to {}
repeat with n from -7 to 100
    if (isPrime(n)) then set end of output to n
end repeat
return output