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


function is_prime_by_trial_division(integer n)
    if n<2 then return 0 end if
    if n=2 then return 1 end if
    if remainder(n,2)=0 then return 0 end if
    for i=3 to floor(sqrt(n)) by 2 do
        if remainder(n,i)=0 then
            return 0
        end if
    end for
    return 1
end function
?filter(tagset(32),is_prime_by_trial_division)
