Function polars::functions::cov_i

pub fn cov_i<T>(a: &ChunkedArray<T>, b: &ChunkedArray<T>) -> Option<f64>where
    T: PolarsIntegerType,
    <T as PolarsNumericType>::Native: ToPrimitive,
    <<T as PolarsNumericType>::Native as Simd>::Simd: Add<<<T as PolarsNumericType>::Native as Simd>::Simd, Output = <<T as PolarsNumericType>::Native as Simd>::Simd> + Sum<<T as PolarsNumericType>::Native> + SimdOrd<<T as PolarsNumericType>::Native>,

Compute the covariance between two columns.