PHP gmp_legendre() Function

The gmp_legendre() function is an in-built function in PHP which computes the Legendre symbol of two GMP numbers (GNU Multiple Precision: For large numbers) $num1 and $num2 passed as parameters to the function and returns it. $num2 must be positive and odd.

Syntax:

gmp_legendre( $num1, $num2 )

Parameters Used:
The function accepts two mandatory parameters $num1 and $num2 as shown in the above syntax. These parameters can be GMP objects in PHP version 5.6 and later, or numeric strings can be passed to the function provided that it is possible to convert those strings to numbers.

Return Value :
This function returns a GMP number (in PHP 5.5 and earlier) or a GMP object (in PHP 5.6 and later) which is the Legendre symbol of the two numbers.

Examples:

Input : $num1 = 2, $num2 = 3
Output : -1

Input : $num1 = 6, $num2 = 15
Output : 0

Below programs will illustrate the gmp_legendre() function:

Program 1

<?php
// PHP program to calculate the
// legendre of two GMP numbers
$num1 = 13;
$num2 = 9907;

//Display the result
echo gmp_legendre($num1, $num2);
?>

Output

1

Program 2

<?php
// PHP program to calculate the
// legendre of two GMP numbers

// creating GMP numbers using gmp_init()
$num1 = gmp_init("124567812");
$num2 = gmp_init("271290907");

//Display the result
echo gmp_legendre($num1, $num2);
?>

Output

-1

Reference : http://php.net/manual/en/function.gmp-legendre.php