Function logaddexp2 

pub fn logaddexp2<T, D>(
    a: &Array<T, D>,
    b: &Array<T, D>,
) -> Result<Array<T, D>, FerrayError>
where
    T: Element + Float + CrMath,
    D: Dimension,

log2(2^a + 2^b), computed in a numerically stable way.