(PHP 4 >= 4.0.4, PHP 5, PHP 7)
gmp_prob_prime — Check if number is "probably prime"
gmp_prob_prime ( GMP|int|string $num [, int $repetitions = 10 ] ) : int
The function uses Miller-Rabin's probabilistic test to check if a number is a prime.
If this function returns 0, num is definitely not prime. If it returns 1, then num is "probably" prime. If it returns 2, then num is surely prime.
Example #1 gmp_prob_prime() example
<?php
// definitely not a prime
echo gmp_prob_prime("6") . "\n";
// probably a prime
echo gmp_prob_prime("1111111111111111111") . "\n";
// definitely a prime
echo gmp_prob_prime("11") . "\n";
?> The above example will output:
0 1 2
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https://www.php.net/manual/en/function.gmp-prob-prime.php