# gmp_prob_prime

(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)

gmp_prob_primeCheck if number is "probably prime"

### Descrição

gmp_prob_prime( `\$num`, int `\$repetitions` = 10): int

The function uses Miller-Rabin's probabilistic test to check if a number is a prime.

### Parâmetros

`num`

The number being checked as a prime.

Um objeto GMP, um int ou uma string numérica.

`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.

Um objeto GMP, um int ou uma string numérica.

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.

### Exemplos

Exemplo #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";?>`

O exemplo acima produzirá:

```0
1
2```

`<?php \$max = 2147483647; \$primesFound = 0; \$probablePrimes = 0; for (\$x = 1; \$x <= \$max; \$x++) { \$primeStatus = gmp_prob_prime(\$x); if (\$primeStatus == 1) { \$probablePrimes++; } else if (\$primeStatus == 2) { \$primesFound++; } } echo "Total primes found: " . \$primesFound . " between 1 and " . \$max . ". Probable primes in this interval: " . \$probablePrimes;?>Based on that the following results were obtained:1 - 100000 - certain primes found: 9592, probable: 01 - 1000000 - certain primes found: 78498, probable: 01 - 10000000 - certain primes found: 78498, probable: 5860811 - 100000000 - certain primes found: 78498, probable: 56829571 - 1000000000 - certain primes found: 78498, probable: 507690361 - 2147483647 - certain primes found: 78498, probable: 105019067`