t from characteristics map kp and compared to the gradient rail_p_setpointinc the minimum of the two values is then added to the setpoint value p_rail_setpoint t u2212 1 from the previous computing step and thus forms the present setpoint value p_rail_setpoint t fig3 shows a schematic diagram for determining the value of the maximum gradient rail_p_setpointinc for modifying rail pressure setpoint value p_rail_setpoint t methods of the related art provide a rail pressure setpoint value characteristics map which corresponds to the requirements at steady state operating points of the engine in dynamic engine use the points of the rail pressure setpoint value characteristics map are connected with the aid of a rail pressure gradient characteristics map for the pressure increase for example in bar s rail_dpsetpointinc_map for regulation and noise related reasons this pressure increase gradient characteristics map results as a function of the engine system quantity injctl_qsetunbal and the engine speed eng_navrg the present exemplary embodiment of the present invention provides for performing in a characteristics map rail_dpsetpointincofs_map a gear dependent gearbx_stgear an actual rotational speed dependent n_actual and a rail pressure actual value dependent railcd_ppeak reduction in the rail pressure increase gradient characteristics map rail_dpsetpointinc_map with the purpose of attaining the setpoint values slower and slower at higher prevailing rail pressures the dependence on the rail pressure actual value permits a direct intervention in the variable to be influenced without passing through the system quantity due to the gear dependent selective use option and the rail pressure actual value dependence the variable is influenced only at lower gears for example and the non relevant pressure.