Let $x \in \mathbb{R}$ and $k \in \mathbb{Z}^+ \cup \{0\}$ then how fast can one compute $x^k$? If $x, k \in  \mathbb{Z}$ then I guess this previous discussion already settled that, How many operations at maximum needed to compute powering of a number, i.e. $N^k$?
How fast can one compute the power of a number?
time complexity;runtime analysis;polynomial time;arithmetic;modular arithmetic