 **`gmp_prob_prime`** is a function in PHP that checks whether or not the argument passed is *probably prime*.

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> This function uses Miller-Rabin's probabilistic test to check the prime nature of numbers.

# 
#  Syntax

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```
gmp_prob_prime(GMP|int|string $num, int $repetitions = 10): int
```
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##
## Parameters

The function takes in two parameters:

* **`num`** - the number that is going to be checked for prime number.

* **`repetitions`** - this is an optional parameter. The value of repetition varies from 5 to 10. The default value is 10. 

---
> `num` and `repetitions` can be a numeric string, GMP object, or of the `int` type.

# 
## Return value

* The function returns `0` if the function is *not prime*.
 
* The function returns `1` if the function is *prime*.

* The function returns `2` if the function is *prime*.

<?php
// number is not prime 
echo gmp_prob_prime("2") . "\n";

// number is probably prime 
echo gmp_prob_prime("111111111") . "\n";

// number is surely prime 
echo gmp_prob_prime("13") . "\n";
?>

What is the gmp_prob_prime function in PHP?

Checks probable prime status using Miller-Rabin test, returning 0, 1, or 2 based on the probability.

What is the gmp_prob_prime function in PHP?

Syntax

Parameters

Return value

Code

Output