program main
  implicit none
  external xsquare
  
  call tabelle (xsquare, -20, 20, 1);
end program

integer function xsquare ( x )
  integer x;
  xsquare = x**2;
  return;
end function

integer function myfunc ( k )
  implicit none
  integer k
  
  myfunc = (2*(k**2) + 4*k + 3)
end function

subroutine tabelle ( f, start, endw, step )
  implicit none
  integer start, endw, step, f
  integer k
  
  if (step .LT. 1) then
    step = 1
  endif

  ! Tabellenkopf
  write (*,*) "+-------------------+"
  write (*,*) "|    x    |    y    |"
  write (*,*) "+-------------------+"
  
  ! x-y-Wertepaare ausgeben
  do k=start, endw, step
    write (*, '(1X,2H| ,I7,3H | , I7, 2H |)') k, f(k)
  enddo
  
  write (*,*) "+-------------------+"
end subroutine