Illustration of the “elementary” dispersion function used in the curve-shifting technique described in Sect. 6. The vertical gray bars represent the terms of the summation of equation 6. The last shown point of light curve Y would not contribute to the dispersion, since it falls into a large gap of X. This elementary dispersion function is not invariant with respect to swapping the curves X and Y. However, our total dispersion estimate is symmetric, as we average these elementary dispersion across all permutations of 2 curves among n. Not shown in this sketch are the polynomial corrections for extrinsic variability. These corrections are optimized against the same total dispersion.