gmp_prob_prime
PHP function
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(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)
Check if number is "probably prime"
Description
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.
Parameters
numThe number being checked as a prime.
Parameter
repetitionsReasonable values of
repetitionsvary from 5 to 10 (default being 10); a higher value lowers the probability for a non-prime to pass as a "probable" prime.Parameter
Return Values
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.
Examples
gmp_prob_prime() example
php
<?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:
output
0
1
2