Examples of the piecewise fit at nine time steps for the run with t_ff/t_vct = 0.9. The normalized residual is plotted as function of cluster characteristic radius in blue solid curves, of which the optimal value is such that the fit is the best. The infall moment W₀(R_avg) is shown in arbitrary units with green dotted curves. The gaseous protocluster radius at which there exists a change in slope is indicated with a red arrow and the size of the semimajor axis is indicated.