gmp_nextprime

(PHP 5 >= 5.2.0, PHP 7)

gmp_nextprimeFind next prime number

Description

GMP gmp_nextprime ( int $a )

Find next prime number

Parameters

a

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

Return the next prime number greater than a, as a GMP number.

Examples

Example #1 gmp_nextprime() example

<?php
$prime1 
gmp_nextprime(10); // next prime number greater than 10
$prime2 gmp_nextprime(-1000); // next prime number greater than -1000

echo gmp_strval($prime1) . "\n";
echo 
gmp_strval($prime2) . "\n";
?>

The above example will output:

11
-997

Notes

Note:

This function uses a probabilistic algorithm to identify primes and chances to get a composite number are extremely small.

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User Contributed Notes 2 notes

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Tommy Lynge Jrgensen
1 month ago
Prime numbers are positive, non-zero numbers that have exactly two factors. No more, no less. So testing negative numbers doesn't really make any sense.
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0
Anonymous
5 months ago
It seems gmp_nextprime on negative numbers always returns 2.
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