pub fn variance(data: &[f64]) -> Option<f64>Expand description
Returns the sample variance of values in the slice.
Uses Bessel’s correction (divides by n-1).
Returns None if the slice has fewer than 2 elements.
§Example
use d3rs::array::variance;
let data = vec![2.0, 4.0, 4.0, 4.0, 5.0, 5.0, 7.0, 9.0];
let var = variance(&data).unwrap();
assert!((var - 4.571428571428571).abs() < 1e-10);