Function jac_element_order 

pub fn jac_element_order(
    d: &Mumford,
    group_order: u128,
    f: &[BigInt],
    p: &BigInt,
) -> u128

The order of a divisor class D in Jac(C) — the least n | group_order with [n]·D = 0. Computed by stripping each prime of group_order as far as still annihilates D.