(PHP 5 >= 5.6.0, PHP 7)
gmp_rootrem — Take the integer part and remainder of nth root
$nth) : array
nth root of
returns the integer component and remainder of the result.
可以是一个 GMP 数据 resouce，或一个可以转换为数值的字符串。
The positive root to take of
A two element array, where the first element is the integer component of the root, and the second element is the remainder, both represented as GMP numbers.