Discrete Fourier Transform in Delphi (in progess)

Here we go...

I plan to coding it in a way that it has flexibility in term of function. So I create two variable ft and ff, represent time domain and frequency domain function as two dimensional array, with the first index as 'function name' so it can be (in future) ft[0,i] as rect(x), ft[1,i] as cos(x) and so on.

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    StringGrid1: TStringGrid;
    Image1: TImage;
    Edit1: TEdit;
    function fourier(a,k:integer):real;
    procedure proses;
    procedure fungsi(a:integer);
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure Image1Click(Sender: TObject);
  private{ Private declarations }
  public{ Public declarations }
  end;
const n=37;m=5;
var
  Form1: TForm1;
  ft,ff: array[0..m,0..n]of real;
  x0,y0:integer;
  sx:real=3;
  sy:real=17;

implementation

{$R *.dfm}
procedure tform1.fungsi(a:integer);
var i:integer;
begin
  for i:=0 to n-1 do begin
    ft[a,i]:=cos(i)+cos(2*i);
    stringgrid1.Cells[1,i+1]:=inttostr(i);
    stringgrid1.Cells[2,i+1]:=floattostr(ft[a,i]);
    image1.Canvas.Pen.Color:=clblack;
    image1.Canvas.MoveTo(x0+round(sx*i),y0);
    image1.Canvas.lineTo(x0+round(sx*i),y0-round(sy*ft[a,i]));
  end;
end;
function tform1.fourier(a,k:integer):real;
var i:integer;jml,j:real;
begin
  jml:=0;
  for i:=0 to n-1 do begin
    j:=i;
    jml:=jml+ft[a,i]*cos(2*PI*k*j/n);
    edit1.Text:=floattostr(jml);
    //application.ProcessMessages;sleep(500);
    //fm:=fm+1*cos(2*PI*j*i/10/11);
  end;
  fourier:=jml;
end;

procedure tform1.proses;
var a,i:integer;z:real;
begin
  a:=0;
  stringgrid1.Cells[3,0]:='f(rect(t))';
  for i:=0 to n-1 do begin
    ff[a,i]:=fourier(a,i);
    stringgrid1.Cells[3,i+1]:=floattostr(ff[a,i]);
    stringgrid1.Cells[4,i+1]:=inttostr(round(ff[a,i]));
    z:=ff[a,i];
    //z:=strtofloat(stringgrid1.Cells[3,i+1]);
    image1.Canvas.Pen.Color:=clblue;
    image1.Canvas.moveto(x0+round(sx*i),y0);
    image1.Canvas.lineTo(x0+round(sx*i),y0-round(sy*z));
    stringgrid1.Cells[0,0]:=floattostr(z);
    stringgrid1.Cells[0,1]:=inttostr(floor(z));
    //application.ProcessMessages;sleep(500);
  end;
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
  proses;
end;

procedure TForm1.FormCreate(Sender: TObject);
var i:integer;
begin
  x0:=round(image1.Width/2);
  y0:=round(image1.Height/2);
  image1.Canvas.pen.Color:=cllime;
  image1.Canvas.MoveTo(0,y0);
  image1.Canvas.lineto(image1.Width,y0);
  image1.Canvas.MoveTo(x0,0);
  image1.Canvas.lineto(x0,image1.Height);
  stringgrid1.RowCount:=n+1;
  //rect(x)
  fungsi(0);
  //tulis stringgrid
  stringgrid1.Cells[0,0]:='no';
  stringgrid1.Cells[0,0]:=inttostr(round(1.5));
  stringgrid1.Cells[1,0]:='t';
  stringgrid1.Cells[2,0]:='rect(t)';

end;

procedure TForm1.Image1Click(Sender: TObject);
begin

end;

end.