Как суммировать столбцы DbGrid?

var ATotal: Array of Integer;
...
for i := 0 to ClientDataSet1.Fields.Count - 1
do if ClientDataSet1.Fields.Fields[i].DataType in [ftInteger, ftSmallInt]
    then SetLength(ATotal, Length(ATotal) + 1);

while not ClientDataSet1.eof
do begin
   n := 0;
    for i := 0 to ClientDataSet1.Fields.Count - 1
    do if ClientDataSet1.Fields.Fields[i].DataType in [ftInteger, ftSmallInt]
        then begin
               Inc(ATotal[n], ClientDataSet1.FieldByName('Calculated').AsInteger + ClientDataSet1.Fields.Fields[i].AsInteger);
               Inc(n);
               end;
    ClientDataSet1.next;
    end;

var bm:TBookmark;
  arr:array[0..1] of double;
begin
  arr[0]:=0;
  arr[1]:=0;
  bm:=ds.GetBookmark;
  ds.DisableControls;
  try
    ds.First;
    while not ds.eof do
    begin
      arr[0]:=arr[0]+ds.FieldByName('aaaa').AsFloat;
      arr[1]:=arr[1]+ds.FieldByName('bbb').AsFloat;
      ds.next;
    end;
  finally
    ds.Gotobookmark(bm);
    ds.EnableControls;
    freeBookmark(bm);
  end;
edit1.text := floattostr(arr[0]);
edit2.text:= floatToStr(arr[1]);
end;