Нужно построить декартов лист

t=StrToFloat(Edit2->Text);
if (t>50 || t<-50) {
 ShowMessage("Ограничения t от -50 до 50 ") ;
} else{
a=0;
b=0;
Button1->Enabled=True;
Button4->Enabled=False;
while (a<=50) {
X=3*a*tan(t)/(1+pow(tan(t),3));
Y=3*a*pow(tan(t),2)/(1+pow(tan(t),3));
a=a+0.1;
Chart1->Series[0]->Active;
Chart1->Series[0]->AddXY(X,Y,clBlack);}
while (b<=50) {
X=3*b*tan(t)/(1+pow(tan(t),3));
Y=3*b*pow(tan(t),2)/(1+pow(tan(t),3));
b=b+15;
Chart1->Series[1]->Active;
Chart1->Series[1]->AddXY(X,Y,clBlack);}}

a=StrToFloat(Edit2->Text);
if (a>50 || a<-50) {
 ShowMessage("Ограничения a от -50 до 50 ") ;} 
else{
Button1->Enabled=True;
Button4->Enabled=False;
while (t<=6.48) {
X=3*a*tan(t)/(1+pow(tan(t),3));
Y=3*a*pow(tan(t),2)/(1+pow(tan(t),3));
t=t+0.1;
Chart1->Series[0]->Active;
Chart1->Series[0]->AddXY(X,Y,clBlack);}}

    Chart1->Series[0]->XValues->Order = loNone;
    Chart1->Series[0]->YValues->Order = loNone;

double x (double a, double fi)
{
  return 3 * a * tan(fi) / (1 + pow(tan(fi), 3));
}
//---------------------------------------------------------------------------
double y (double a, double fi)
{
  return 3 * a * tan(fi) * tan(fi) / (1 + pow(tan(fi), 3));
}
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
  Refresh();
 
  Canvas->Pen->Color = clBlue;
  Canvas->MoveTo(0, ClientHeight/2);
  Canvas->LineTo(ClientWidth, ClientHeight/2);
  Canvas->MoveTo(ClientWidth/2, 0);
  Canvas->LineTo(ClientWidth/2, ClientHeight);
 
  double i, step = 0.0001, a = 5, scale = 15, r = 1, temp_x, temp_y;
  a = StrToFloatDef(Edit1->Text, a);
 
  Canvas->Pen->Color = clRed;
  for (i = 0; i < 2*M_PI; i += step)
  {
    temp_x = ClientWidth/2 + scale * x(a, i);
    temp_y = ClientHeight/2 - scale * y(a, i);
    Canvas->Ellipse(temp_x - r, temp_y - r, temp_x + r, temp_y + r);
  //    Canvas->Pixels[temp_x][temp_y] = clRed;
  }
 
  for (int i = 0; i <= ClientWidth; i++)
    if (i%7 < 4)
      Canvas->Pixels[i][i + scale * a + r] = clBlack;
}