Function initial 

pub fn initial(
    x: &mut [F],
    sys: &mut PackContext,
    precision: F,
    discale: F,
    sidemax: F,
    nloop0: usize,
    pbc: Option<([F; 3], [F; 3], [bool; 3])>,
    avoid_overlap: bool,
    movebad_cfg: &MoveBadConfig<'_>,
    rng: &mut impl Rng,
)

Full initialization procedure. Faithful port of initial.f90.