gmp_prob_prime
(PHP 4 >= 4.0.4)
gmp_prob_prime -- Check if number is "probably prime"
Description
int gmp_prob_prime ( resource a [, int reps])
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. 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.
The function uses Miller-Rabin's probabilistic test.
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 printout of the above program will be:
0
1
2
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