invertOrd function
Implementation
List<double> invertOrd(List<double> base, List<double> diffs, int d){
if (d==0) return List<double>.from(diffs);
var cur=List<double>.from(diffs), hist=List<double>.from(base); List<double> res=[];
for (int k=0;k<d;k++){ double last=hist.last; final inv=<double>[]; for (final v in cur){ last+=v; inv.add(last); } res=inv; hist=hist+inv; cur=res; }
return res;
}