subroutine r8_swap ( x, y )

!*****************************************************************************80
!
!! R8_SWAP swaps two R8 values.
!
!  Licensing:
!
!    This code is distributed under the GNU LGPL license.
!
!  Modified:
!
!    01 May 2000
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input/output, real ( kind = rk ) X, Y.  On output, the values of X and
!    Y have been interchanged.
!
  implicit none

  integer, parameter :: rk = kind ( 1.0D+00 )

  real ( kind = rk ) x
  real ( kind = rk ) y
  real ( kind = rk ) z

  z = x
  x = y
  y = z

  return
end