Function bessel_i_ratio_deriv_1m 

pub fn bessel_i_ratio_deriv_1m<P, E, V>(c: V, x: V, nu: V) -> V
where
    P: Policy,
    E: FloatElement,
    V: FloatVector<Element = E>,

A' from the complement c = 1 - A, with 1 - A^2 as c (2 - c): no cancellation where A is within an ulp of 1.