In the current study, we present a novel intuitive graphical method for the simulation of nonlinear effects on stretched pulses, characterized by a large time-bandwidth product. By way of example, this method allows precise determination of effects occurring in CPA (chirped pulse amplification) laser chains, such as the pre-pulse generation by the nonlinear Kerr effect. This method is not limited to first-order dispersion and can handle all resulting distortions of the generated pre-pulse.