(PHP 5 >= 5.6.0, PHP 7, PHP 8)
gmp_root — Take the integer part of nth root
Takes the nth root of num and
returns the integer component of the result.
numGMP 对象、int 或 string，可以按照跟在 gmp_init() 中使用字符串并自动检测 base（即当 base 等于 0 时）相同的逻辑将其解释为数字。
nth
The positive root to take of num.
The integer component of the resultant root, as a GMP number.