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


for i = 1 to 99
    if isPrime(i) then print string(i); " "; 
next i
end
 
function isPrime(v)
    if v < 2 then return False
    if v mod 2 = 0 then return v = 2
    if v mod 3 = 0 then return v = 3
    d = 5
    while d * d <= v
        if v mod d = 0 then return False else d += 2
    end while
    return True
end function