Function gini_coefficient 

pub fn gini_coefficient(sorted: &[usize]) -> f64

Return the Gini coefficient for an ascending-sorted integer slice.

Examples

use tokmd_math::gini_coefficient;

// Perfectly equal distribution has a Gini of 0
assert!((gini_coefficient(&[5, 5, 5, 5]) - 0.0).abs() < 1e-10);

// Empty slice returns 0
assert_eq!(gini_coefficient(&[]), 0.0);

// Unequal distribution produces a positive Gini
assert!(gini_coefficient(&[1, 1, 1, 100]) > 0.0);

Single-element and all-zero slices:

use tokmd_math::gini_coefficient;

// A single element has zero inequality
assert_eq!(gini_coefficient(&[42]), 0.0);

// All zeros also return 0 (no division by zero)
assert_eq!(gini_coefficient(&[0, 0, 0]), 0.0);