invertND function
Toplam inversiyon: önce seasonal, sonra ordinary geri al
Implementation
List<double> invertND(List<double> history, List<double> diffs, int d, int s, int D) {
final afterSeasonal = invertSeasonal(history, diffs, s, D);
final full = invertOrdinary(history + afterSeasonal, afterSeasonal, d);
return full;
}