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


bcpowmod

(PHP 5)

bcpowmodRaise an arbitrary precision number to another, reduced by a specified modulus

说明

string bcpowmod ( string $left_operand , string $right_operand , string $modulus [, int $scale ] )

Use the fast-exponentiation method to raise left_operand to the power right_operand with respect to the modulus modulus.

参数

left_operand

The left operand, as a string.

right_operand

The right operand, as a string.

modulus

The modulus, as a string.

scale

此可选参数用于设置结果中小数点后的小数位数。 也可通过使用 bcscale() 来设置全局默认的小数位数,用于所有函数。

返回值

Returns the result as a string, or NULL if modulus is 0.

注释

Note:

Because this method uses the modulus operation, numbers which are not positive integers may give unexpected results.

范例

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() - Raise an arbitrary precision number to another
  • bcmod() - Get modulus of an arbitrary precision number


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