Function rgsl::power::pow_int

pub fn pow_int(x: f64, n: i32) -> f64

This routine computes the power xⁿ for integer n. The power is computed using the minimum number of multiplications. For example, x⁸ is computed as ((x^2)2)2, requiring only 3 multiplications. For reasons of efficiency, these functions do not check for overflow or underflow conditions.

use rgsl::power;
/* compute 3.0**12 */
double y = gsl_sf_pow_int(3.0, 12);