Function bessel_kv_impl 

pub fn bessel_kv_impl<P, E, V, const AS: usize, const AD: usize, const AL: usize, const ALD: usize, const BS: usize, const BD: usize, const BL: usize, const BLD: usize, const IS: usize, const IL: usize, const IF: usize, const JS: usize, const JL: usize, const JF: usize, const SCALED: bool>(
    x: V,
    n: V,
    t0: &BesselK<E, AS, AD, AL, ALD>,
    t1: &BesselK<E, BS, BD, BL, BLD>,
    ti0: &BesselI<E, IS, IL, IF>,
    ti1: &BesselI<E, JS, JL, JF>,
) -> V
where
    E: FloatElement,
    V: FloatVector<Element = E> + TranscendentalMathWithPolicy,
    P: Policy,

K_n(x) with a per-lane order, or e^{x} K_n(x) when SCALED.

Upward recurrence, each lane freezing once it reaches its own order, the hermitev shape. The loop runs to the packet’s largest order.