Php/docs/function.gmp-prob-prime
gmp_prob_prime
(PHP 4 >= 4.0.4, PHP 5, PHP 7)
gmp_prob_prime — Check if number is "probably prime"
Description
gmp_prob_prime
( GMP $a
[, int $reps = 10
] ) : int
The function uses Miller-Rabin's probabilistic test to check if a number is a prime.
Parameters
aThe 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.
repsReasonable values of
repsvary 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() example
<?php// definitely not a primeecho gmp_prob_prime("6") . "\n";// probably a primeecho gmp_prob_prime("1111111111111111111") . "\n";// definitely a primeecho gmp_prob_prime("11") . "\n";?>
The above example will output:
0 1 2
