Function pow10 

pub fn pow10(x: f64) -> f64

10^x from basic arithmetic: x = n + f with n = ⌊x⌋, 10^f as exp(f ln 10 / 16)¹⁶ by a degree-11 Taylor polynomial, and 10^|n| by exact multiplication (for |n| ≤ 22).

Within 1e-14 relative of f64::powf on [−22, 22]; outside, the result is clamped to 1e±22 times 10^f.