Luminosity (bottom axis) and stellar mass (top axis) function of red-sequence cluster members. The solid line is the mean model fitted to the individual galaxy data, while the shading indicates the 68% uncertainty (highest posterior density interval). Points and approximated error bars are derived by binning galaxies in magnitude bins, adopting approximated Poisson errors summed in quadrature, as commonly done in the literature. The top axis indicates the corresponding stellar mass, based on our standard BC03 SSP model with z_f = 3.