function det(var p; const size: integer): double;

   function minusOne (n : integer): integer;
   begin
      minusOne := (1 - 2 * Byte (Odd (n)));
   end;
   function get_addr(i, j : integer;
            const n: integer) : integer;
   begin
      get_addr := pred (i) * n + j
   end;

   type vector = array[1 .. n * n] of double;

var
   my_p : vector absolute p;
   pp : ^vector;
   s : double;
   i, j, curr: integer;
begin
   s := 0.0;
   if size = 2 then
   begin
      det := my_p[1]*my_p[4] - my_p[2]*my_p[3]; exit
   end;

   for i := 1 to size do
   begin
      GetMem (pp, Sqr (pred (size)) * sizeof (double));
      curr := 1;
      for j := 1 to size do
         if j <> i then
         begin
            move (my_p[get_addr (j, 2, size)],
                  pp^[get_addr (curr, 1, pred (size))],
                  pred(size) * sizeof(double));
            inc (curr);
         end;

      s := s + minusOne (succ(i)) * my_p[get_addr (i, 1, size)] *
               det(pp^, pred (size));
      FreeMem (pp, Sqr (pred (size)) * sizeof (double))
   end;
   det := s
end;