(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)
gmp_prob_prime — Check if number is "probably prime"
The function uses Miller-Rabin's probabilistic test to check if a number is a prime.
numThe number being checked as a prime.
A GMP object, an int,
or a string that can be interpreted as a number following the same logic
as if the string was used in gmp_init() with automatic
base detection (i.e. when base is equal to 0).
repetitions
Reasonable values
of repetitions vary from 5 to 10 (default being
10); a higher value lowers the probability for a non-prime to
pass as a "probable" prime.
A GMP object, an int,
or a string that can be interpreted as a number following the same logic
as if the string was used in gmp_init() with automatic
base detection (i.e. when base is equal to 0).
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