hello..sorry for interrupt you guys… can anyone help me to solve my problem. actually i use numerical method (split step fourier method) in matlab to prove the effect of fiber losses, dispersion and non-linearity in optical soliton and also need to compare that result with optisystem. actually, i already got the result from optisystem for fiber losses, dispersion and SPM. i compared the effect of fiber losses (alpha), GVD (beta2), and SPM (gamma) based on the 3 physical length. (i picked 10km, 20km, and 30km).but here, i need to tally the result with matlab (split step fourier method) n must be the same result with optisystem. i try to change the coding, but it failed. since i picked 3 physical length in optisystem result, so i need to setup the same physical length in matlab coding to test the effect of fiber losses, GVD,and SPM.. i hope you guys help me to solve this problem.. i tired to thinking how to solve this problem. here i attached the coding and the result from optisystem.