Function std_dev_population 

pub fn std_dev_population<T>(data: &[T]) -> StatsResult<f64>
where
    T: ToPrimitive + Debug,

Population standard deviation (sqrt(variance_population)).

Same as numpy.std(data) / numpy.std(data, ddof=0).

Examples

use rs_stats::prob::std_dev_population;
let s = std_dev_population(&[1.0, 2.0, 3.0, 4.0, 5.0]).unwrap();
assert!((s - 2.0_f64.sqrt()).abs() < 1e-12);