Comparison of the calculated light ray deflection angle from Equation (16) (left panel) and the lensing factor d cos α/d cos ψ that appears in Equation (20) (right panel) as a function of the light ray emission angle α. The insets show a zoom-in around α = π/2, where the largest discrepancies between the codes are apparent. The line colors correspond to the results generated by the CU (black), GSFC-M (orange), GSFC-S (blue), Alberta (purple), and IM (yellow) codes. The different curves are mostly indistinguishable because the agreement between the codes is excellent.