Function variance 

pub fn variance<T: AsRef<[f32]>>(values: T) -> f32

Calculate statistical variance for values.

Return NaN if the values are empty.

Filter NaN values in the stream.

Example

#[macro_use]
use numeric_statistics::assert_eq_f32;
use numeric_statistics::f32::variance::*;
let values = &[1.0, 2.0, 4.0];
let variance = variance(values);
assert_eq_f32!(variance, 2.3333333 as f32);