Function polarized_angular 

pub(crate) fn polarized_angular<const N: usize>(
    l: i32,
    m: i32,
    [cosine, sine]: [Jet<N>; 2],
    [mode_pol, pol]: [u8; 2],
    helicity: bool,
) -> Jet<N>

Angular factor coupling the vector spherical wave (l, m) of polarization mode_pol to a plane wave of polarization pol whose direction has the polar cosine and sine given: tau -+ pi for negative (0) or positive (1) helicity; in parity polarization tau for the mode’s own polarization and pi for the other. The polarization module states this rule for the vector waves themselves.