var a: TVec; c: double; aMean: double; begin CreateIt(a); try a.SetIt(False,[1,2,3,4]); aMean := a.Mean; c := a.StdDev(aMean); //if both Mean and StdDev are required this is faster // c := a.StdDev; //this is an alternative. finally FreeIt(a); end; end;