Function hypervolume 

pub fn hypervolume(points: &[Vec<f64>], r: &[f64]) -> f64

Exact dominated hypervolume of points w.r.t. the reference point r (minimization: every point should weakly dominate r; components beyond r contribute zero). Duplicates and dominated points are handled correctly (they simply add no exclusive volume).

2D uses an O(n log n) sweep; 3+ objectives use the WFG exclusive decomposition — exact but exponential in the worst case, intended for the front sizes typical of population-based MOEAs (≤ a few hundred points, 2–4 objectives).