anchor.diff:    FunctionsList[2] := 'sqr';
     FunctionsList[3] := 'sqrt';
     FunctionsList[4] := 'pow';
  +//  FunctionsList[5] := 'sum';
   end;
     
   procedure GenerateOperatorMap;
  
positive.code:           Term1 := StrToFloat(Stack.Pop);
            Term2 := StrToFloat(Stack.Pop);
            Value := Power(Term2, Term1);
            Stack.Push(Value);
          end
            else begin
  
negative.code:   expr := 'sin(pi / 2)';
    expr := 'sin(-pi / 2)';
    expr := 'srt(4)';
    expr := 'pow(2, 2)';
    expr := 'sum(1, 2, 3)';
              
    Writeln(Expr + '=' + EvalExpr(expr));
    Readln(expr);
  