Function assert_symmetric 

pub fn assert_symmetric<F>(
    matrix: &ArrayView2<'_, F>,
    name: &str,
    tolerance: F,
) -> CoreResult<()>
where
    F: Float + Display,

Assert that a 2-D matrix is symmetric within a given tolerance.

Checks |A[i,j] - A[j,i]| <= tolerance for all i,j.