Function bessel_j0_impl 

pub fn bessel_j0_impl<P, E, V, const N1: usize, const N2: usize, const NH: usize>(
    x: V,
    t: &BesselJ<E, N1, N2, NH>,
) -> V
where
    E: FloatElement,
    V: FloatVector<Element = E> + TranscendentalMathWithPolicy,
    P: Policy,

$J_0(x)$. Even in x.