fn percentile(sorted_values: &[f64], percentile: f64) -> f64Expand description
Calculate percentile using linear interpolation on a sorted slice.
Computes rank = percentile × (n - 1) where n is the array length. If the rank falls
between two indices, linearly interpolates between those values. For example, with 100 values,
p90 computes rank = 0.9 × 99 = 89.1, then returns values[89] × 0.9 + values[90] × 0.1.
Returns 0.0 for empty input.