mencari titik koordinat dengan menggunakan pengulangan 1

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    PaintBox1: TPaintBox;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
  {deklarasi funsi titik koordinat x = 0}
function canvasX (LojikX : Double): integer;
begin
  result := Round(LojikX + 100);
end;

{deklarasi funsi titik koordinat y = 0}
function canvasY (LojikY : Double): integer;
begin
  result := round(100 - LojikY);
end;
 var
 i : integer;
 j : real;

procedure TForm1.Button1Click(Sender: TObject);
begin
   with Paintbox1.canvas do
  begin
    moveto(canvasX(-100),canvasY(0));  //garis sumbu X
    lineto(canvasX(100),canvasY(0));
    moveto(canvasX(0),canvasY(-100));  //garis sumbu Y
    lineto(canvasX(0),canvasY(100));

   //pixels[canvasX(-1),canvasY(1)] := clred;
   //pixels[canvasX(-5),canvasY(5)] := clred;
   //pixels[canvasX(-10),canvasY(10)] := clred;
   //pixels[canvasX(-15),canvasY(15)] := clred;
   //pixels[canvasX(-20),canvasY(20)] := clred;

    {menggambar grafik fungsi}
   { for i := -10 to 10 do
    begin
      pixels[canvasX(i),canvasY(i*i)] := clred;
      pixels[canvasX(i),canvasX(i*i)] := clblue;
      pixels[canvasY(i*i),canvasX(i)] := clgreen;
      pixels[canvasX(i*i),canvasY(i)] := clblack;
 end; }

 j := -10;  {inisialisasi nilai awal}
 while j <= 10 do
 begin
   pixels[canvasX(j),canvasY(j*j-100)] := clred;
   j := j + 0.0001;
   pixels[canvasX(j),canvasX(j*j-100)] := clblue;
   j := j + 0.0001;
   pixels[canvasy(j*j-100),canvasX(j)] := clgreen;
   j := j + 0.0001;
   pixels[canvasX(j*j-100),canvasY(j)] := clblack;
   j := j + 0.0001


 end;
    end;
  end;

end.

.'. ganti tulisan yang bewarnah biru dengan kode warnah yg pingin anda gunakan.