differenceSeas function
Implementation
List<double> differenceSeas(List<double> x, int s, int D){
if (D==0) return List<double>.from(x);
var y=List<double>.from(x);
for (int k=0;k<D;k++){ final ny=<double>[]; for (int t=s;t<y.length;t++) ny.add(y[t]-y[t-s]); y=ny; }
return y;
}