(* d_herbst.m *)

u[1][n_]'[t]:= Expand[(aa+(1/6)*hh^2*dd*u[1][n][t])*( (bb/(dd*hh^3))*
((1/2)*u[1][n+2][t]-u[1][n+1][t]+u[1][n-1][t]-(1/2)*u[1][n-2][t])+
(1/(12*hh))*(u[1][n+1][t]+2*u[1][n][t]+u[1][n-1][t])*
(u[1][n+1][t]-u[1][n-1][t])+
(1/(12*hh))*u[1][n+1][t]*(u[1][n+2][t]-u[1][n][t])+
(1/(12*hh))*u[1][n-1][t]*(u[1][n][t]-u[1][n-2][t]) )];

noeqs = 1;
name = "Herbst's Equation";
parameters = {hh,dd};
weightpars = {aa,bb};

formrho = 0;

(*
weightu[1] = 1/2; 
weight[aa] = 1/2; 
weight[bb] = 1/2;
*)

(* d_herbst.m *)