(PHP 4, PHP 5)
bcpow — Raise an arbitrary precision number to another
Raise left_operand to the power right_operand.
The left operand, as a string.
The right operand, as a string.
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。
Returns the result as a string.
Example #1 bcpow() example
<?php
echo bcpow('4.2', '3', 2); // 74.08
?>
Note:
bcpow() may return a result with fewer digits after the decimal point than the scale parameter would indicate. This only occurs when the result doesn't require all of the precision allowed by the scale. For example:
Example #2 bcpow() scale example
<?php
echo bcpow('5', '2', 2); // prints "25", not "25.00"
?>