Function rgsl::statistics::wkurtosis

pub fn wkurtosis(
    w: &[f64], 
    wstride: usize, 
    data: &[f64], 
    stride: usize, 
    n: usize
) -> f64

This function computes the weighted kurtosis of the dataset data.

kurtosis = ((\sum w_i ((x_i - \Hat x)/\Hat \sigma)^4) / (\sum w_i)) - 3