Left: original pulse profiles described with a Fourier series, normalized to unity in four different energy ranges. Right: best decomposition of the original pulse profiles in two symmetric functions, corresponding to region A. The vertical lines indicate the ranges for the symmetry points for both single-pole pulse profiles, Φ₁ (dashed lines) and Φ₂ (dash-dotted lines). The dotted horizontal lines represent the unmodulated flux left available to distribute between the two functions.