<?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: 0
1 - 1000000 - certain primes found: 78498, probable: 0
1 - 10000000 - certain primes found: 78498, probable: 586081
1 - 100000000 - certain primes found: 78498, probable: 5682957
1 - 1000000000 - certain primes found: 78498, probable: 50769036
1 - 2147483647 - certain primes found: 78498, probable: 105019067
gmp_prob_prime
(PHP 4 >= 4.0.4, PHP 5, PHP 7, PHP 8)
gmp_prob_prime — Check if number is "probably prime"
Beschreibung
The function uses Miller-Rabin's probabilistic test to check if a number is a prime.
Parameter-Liste
-
num -
The number being checked as a prime.
Ein GMP-Object, ein Integer oder eine numeriche Zeichenkette.
-
repetitions -
Reasonable 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.Ein GMP-Object, ein Integer oder eine numeriche Zeichenkette.
Rückgabewerte
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.
Beispiele
Beispiel #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";
?>Das oben gezeigte Beispiel erzeugt folgende Ausgabe:
0 1 2
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User Contributed Notes 1 note
florin dot ciuica at yahoo dot com ¶
10 years ago
