GMP_PROB_PRIME(3) 1 GMP_PROB_PRIME(3)
gmp_prob_prime - Check if number is ";probably prime"
SYNOPSIS
int gmp_prob_prime (GMP $a, [int $reps = 10])
DESCRIPTION
The function uses Miller-Rabin's probabilistic test to check if a number is a prime.
PARAMETERS
o $a
- The number being checked as a prime. Either a GMP number resource in PHP 5.5 and earlier, a GMP object in PHP 5.6 and later, or
a numeric string provided that it is possible to convert the latter to a number.
o $reps
- Reasonable values of $reps vary from 5 to 10 (default being 10); a higher value lowers the probability for a non-prime to pass
as a "probable" prime. Either a GMP number resource in PHP 5.5 and earlier, a GMP object in PHP 5.6 and later, or a numeric string
provided that it is possible to convert the latter to a number.
RETURN VALUES
If this function returns 0, $a is definitely not prime. If it returns 1, then $a is "probably" prime. If it returns 2, then $a is surely
prime.
EXAMPLES
Example #1
gmp_prob_prime(3) example
<?php
// definitely not a prime
echo gmp_prob_prime("6") . "
";
// probably a prime
echo gmp_prob_prime("1111111111111111111") . "
";
// definitely a prime
echo gmp_prob_prime("11") . "
";
?>
The above example will output:
0
1
2
PHP Documentation Group GMP_PROB_PRIME(3)
