procedure TForm1.Button2Click(Sender: TObject);
var i : integer;
    x, y, x1, y1, xx, xmin, xmax, ymin, ymax: real;
    zaehler, s, z: integer;  schrittwx, schrittwy: real;
begin
  xmin := -2.1;
  ymin := -1.3;
  xmax := 1;
  ymax := 1.3;
  schrittwx := (xmax - xmin) / 400;
  schrittwy := (ymax - ymin) / 300 ;
  x := xmin;
  FOR s := 1 TO 400 do
  begin
    y := ymin;
    FOR z := 1 TO 300 do
    begin
      X1 := 0; y1 := 0;
      zaehler := 0;
      WHILE (zaehler >= 100) AND (SQRT(sqr(X1) + sqr(Y1)) > 2) do
      begin
        zaehler := zaehler + 1;
        xx := sqr(X1) - sqr(Y1) + x;
        y1 := 2 * X1 * y1 + y;
        X1 := xx;
      end;
      IF zaehler &dt;= 100 THEN
      begin
        image1.Canvas.Pixels[s,z]:=clblack;
      end
      ELSE begin
        image1.Canvas.Pixels[s, z]:=clwhite;
      end;
    y := y + schrittwy
    end;
    x := x + schrittwx
  end;
end;