Исправить ошибки в программе, работающей с матрицами

unit Main;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls, StdCtrls, Spin, Grids;
 
type
  TForm1 = class(TForm)
    Panel1: TPanel;
    Panel2: TPanel;
    StringGrid1: TStringGrid;
    Button2: TButton;
    StringGrid2: TStringGrid;
    Splitter1: TSplitter;
    Button3: TButton;
    Button4: TButton;
    procedure Button3Click(Sender: TObject);
 
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
  kol: integer;
  obr: array[0..300, 0..300] of real;
 
implementation
 
{$R *.dfm}
 
function Obratis: boolean;
var k, i, j: integer;
  b: array[0..300, 0..300] of real;
begin
  for k := 0 to kol - 1 do
  begin
    for i := 0 to kol - 1 do
      for j := 0 to kol - 1 do
      begin
 
       if obr[k, k] = 0 then
        begin
          showmessage('Îïðåäåëèòåëü ðàáåí íóëþ. Îáðàòíîé ìàòðèöû íåò.');
          result := false;
          exit;
        end;
        if (i = k) and (j = k) then
          b[i, j] := 1 / obr[i, j];
 
 
        if (i = k) and (j <> k) then
          b[i, j] := -obr[i, j] / obr[k, k];
        if (i <> k) and (j = k) then
          b[i, j] := obr[i, k] / obr[k, k];
 
        if (i <> k) and (j <> k) then
          b[i, j] := obr[i, j] - obr[k, j] * obr[i, k] / obr[k, k];
      end;
    for i := 0 to kol - 1 do
      for j := 0 to kol - 1 do obr[i, j] := b[i, j];
  end;
  result := true;
end;
 
procedure TForm1.Button3Click(Sender: TObject);
begin
  form1.Close;
end;
 
 
 
procedure TForm1.Button1Click(Sender: TObject);
var i, j: integer;
begin
  randomize;
  for i := 0 to kol - 1 do
    for j := 0 to kol - 1 do
      StringGrid1.Cells[i, j] := IntToStr(random(200) - 100);
end;
 
procedure TForm1.FormCreate(Sender: TObject);
begin
  kol := 1;
end;
 
procedure TForm1.Button2Click(Sender: TObject);
var i, j: integer;
  i1, j1: integer;
begin
  i1 := 1;
  j1 := 1;
  try
    for i := 0 to kol - 1 do
      for j := 0 to kol - 1 do
      begin
        i1 := i;
        j1 := j;
        obr[i, j] := StrToFloat(StringGrid1.Cells[j, i]);
      end;
  except
    ShowMessage('Îøèáêà ïðè ââîäå ÷èñëà â ñòîëáöå ' + IntToStr(j1 + 1) + ' ñòðîêå ' + IntToStr(i1 + 1) + '!');
    exit;
  end;
 
  if Obratis then
    for i := 0 to kol - 1 do
      for j := 0 to kol - 1 do
        StringGrid2.Cells[i, j] := FloatToStr(Round(1000 * obr[j, i]) / 1000)
  else
    for i := 0 to kol - 1 do
      for j := 0 to kol - 1 do
        StringGrid2.Cells[i, j] := '';
end;
 
procedure TForm1.Button4Click(Sender: TObject);
var
f: textfile;
i, j, a: integer;
begin
 assignfile(f, '1.txt');
 reset(f);
 readln(f,kol);
 StringGrid1.ColCount := kol;
 StringGrid1.RowCount := kol;
 StringGrid2.ColCount := kol;
 StringGrid2.RowCount := kol;
    for j := 0 to kol - 1 do
       for i := 0 to kol - 1 do
    begin
       read(f, a);
       StringGrid1.Cells[i, j] := IntToStr(a);
    end;
  closefile(f);
end;
end.