gmp_invert

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

gmp_invertInverse by modulo

说明

gmp_invert ( GMP|int|string $num1 , GMP|int|string $num2 ) : GMP|false

Computes the inverse of num1 modulo num2.

参数

num1

GMP 对象或 int ,或数字string

num2

GMP 对象或 int ,或数字string

返回值

A GMP number on success or false if an inverse does not exist.

范例

Example #1 gmp_invert() example

<?php
echo gmp_invert("5""10"); // no inverse, outputs nothing, result is FALSE
$invert gmp_invert("5""11");
echo 
gmp_strval($invert) . "\n";
?>

以上例程会输出:

9

User Contributed Notes

athamidn at gmail dot com 06-Apr-2020 11:31
Example #2 gmp_invert() example
<?php
echo gmp_invert("5", "10"); // no inverse, outputs nothing, result is FALSE

It means (5 * x ) mod 10 = 1. And with this function we want a value for x, because of mod 10, x should be {1.. 10-1(9)}, so :

5 * 1 mod 10 = 5
5
* 2 mod 10 = 0
5
* 3 mod 10 = 5
5
* 4 mod 10 0
5
* 5 mod 10 = 5
5
* 6 mod 10 = 0
5
* 7 mod 10 = 5
5
* 8 mod 10 = 0
5
* 9 mod 10 = 5
We don
't have any 1 in the results. so it will be False.

$invert = gmp_invert("5", "11");

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

The above example will output:

9

5 * 9 mod 11 = 1
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