Generate Payment Schedule

procedure TfrmLeasePaymentSchedule.btnGenerateClick(Sender: TObject);
var
  sbb: Real;
  bul: Int64;
  jmp: Integer;
  prd: Integer;
  hrg: Real;
  ssa: Real;
  ssb: Real;
  anp: Real;
  anb: Real;
  tgl: Integer;
  iii: Integer;
  car: Integer;
  dep: Real;
  wkt: Integer;
  rat: Real;
  sis: Real;
  net: Real;
  vpm: Real;
begin
  hrg := edhargaBarang.Float;
  net := edNetFinance.Float;
  dep := edUangMuka.Float;
  sis := edNilaiSisa.Float;
  prd := cbPeriode.CurrentID;
  rat := edTingkatBunga.Float / 12 / prd / 100;
  wkt := edJangkaWaktu.Integer;
  jmp := trunc(wkt / prd);
  car := 2 - cbTypePembayaran.Index;
  tgl := trunc(dtAcc.Date);
  tgl := trunc(ifthen(cbTypePembayaran.Index = 1, IncMonth(tgl, -1), tgl));
  vpm := PMT(hrg, dep, sis, wkt, rat, car);
  bul := PembulatanLease(vpm);
  ssb := bul * wkt - net;
  ssa := bul * wkt;

  edAngsuran.Float     := vpm;
  edPembulatan.Integer := bul;


  Grid1.RowCount    := jmp + 2;
  Grid1.Cells[5, 1] := edNetFinance.Text;
  Grid1.Cells[6, 1] := FloatToDec(ssb, 2);
  Grid1.Cells[7, 1] := FloatToDec(ssa, 2);

  for iii := 2 to Grid1.RowCount - 1 do
  begin
    sbb := DecToFloat(Grid1.Cells[6, iii - 1]);
    anb := round(net * rat);//angsuran bunga;
    anb := ifthen((car = 1) and (iii = 2), 0, anb);
    anp := bul - anb;
    tgl := Trunc(IncMonth(tgl));
    ssb := ssb - anb;
    ssb := ifthen(ssb  <= 0, 0, ssb);
    ssa := ssa - bul;
    net := net - anp;
    net := ifthen(ssb  =  0, ssa, net);
    anb := ifthen(ssb  =  0, sbb, anb);
    anb := ifthen(ssa  <= 0, sbb, anb);
    anp := bul - anb;
    net := ifthen(ssa <= 0, 0, net);
    ssb := ifthen(ssa <= 0, 0, ssb);

    Grid1.Cells[0, iii] := IntToStr(iii - 1);
    Grid1.Cells[1, iii] := FormatDateTime('dd-MM-YYYY', tgl);
    Grid1.Cells[2, iii] := FloatToDec(anp, 2);
    Grid1.Cells[3, iii] := FloatToDec(anb, 2);
    Grid1.Cells[4, iii] := FloatToDec(bul, 2);
    Grid1.Cells[5, iii] := FloatToDec(net, 2);
    Grid1.Cells[6, iii] := FloatToDec(ssb, 2);
    Grid1.Cells[7, iii] := FloatToDec(ssa, 2);
  end;
end;