Module polarization 

Polarization conventions of vector waves: how the polarization index pol combines the two multipole parts M and N of a wave.

• Parity: pol = 0 is M and pol = 1 is N.
• Helicity: (N + (2 pol - 1) M) / sqrt(2), so pol = 0 is negative and pol = 1 positive helicity.

Upstream: the convention of treams.special.vsw_A and vcw_A. polarized_wave applies it to vector waves, and legendre::polarized_angular applies the same sign 2 pol - 1 (helicity_sign) to the angular factors tau + (2 pol - 1) pi of plane-wave expansions.

Functions

check_pol 🔒

Checks that pol is a polarization index: 0 or 1.

helicity_sign 🔒

The sign 2 pol - 1 of polarization index pol in the helicity convention: -1 for negative helicity (0), +1 for positive helicity (1).

pol_index

The polarization index of an integer label, which must be 0 or 1.

polarized_wave 🔒

The vector wave of polarization pol from its M and N parts: M (0) or N (1) in parity polarization, (N -+ M) / sqrt(2) for negative (0) or positive (1) helicity.