PHP Manual
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bcpowmod

(PHP 5)

bcpowmod -- Raise an arbitrary precision number to another, reduced by a specified modulus

Description

string bcpowmod ( string x, string y, string modulus [, int scale] )

Use the fast-exponentiation method to raise x to the power y with respect to the modulus modulus. The optional scale can be used to set the number of digits after the decimal place in the result.

注: Because this method uses the modulus operation, non-natural numbers may give unexpected results. A natural number is any positive non-zero integer.

例

The following two statements are functionally identical. The bcpowmod() version however, executes in less time and can accept larger parameters.


<?php
$a = bcpowmod($x, $y, $mod);

$b = bcmod(bcpow($x, $y), $mod);

// $a and $b are equal to each other. 

?>

参见

bcpow() 和 bcmod().

后退	起点	前进
bcpow	上一级	bcscale