Function true_range_series 

pub fn true_range_series(
    high: &[f64],
    low: &[f64],
    close: &[f64],
) -> FinanceResult<Vec<f64>>

Per-bar true range series (same length as inputs). Bar 0 uses H−L only.

use finance_solution::stocks::ta::true_range_series;
let h = [10.0, 12.0];
let l = [9.0, 10.0];
let c = [9.5, 11.0];
let tr = true_range_series(&h, &l, &c).unwrap();
assert!((tr[0] - 1.0).abs() < 1e-12);
assert!((tr[1] - 2.5).abs() < 1e-12); // max(2, |12-9.5|, |10-9.5|)