C-functions on the wavelength range 847−874 nm, obtained with two of our methods for a late-type and an early-type object as indicated (synthetic spectra with only photon noise, no rotational broadening and “source” velocity = 50   km   s^-1). Top row: spectrum grid step = 0.027 nm, continuum S/N = 60; bottom row: spectrum grid step = 0.088 nm, continuum S/N = 7. The red lines indicate the average over a large number of C-functions obtained from spectra differing only by their noise realization.