Removed the functions \verb=cut_off.m= and \verb=change_ak.m= from the code and replaced the calls to these functions by simple one- or two-liners that do the same. Removed call to \verb=eval= in \verb=optimize_surface_exact= and substituted calls in \verb=slope_error.m= to \verb=gsw_alpha= and \verb=gsw_beta= by \verb=gsw_rho_alpha_beta=.