#! /usr/bin/env python
#
def r8_swap ( x, y ):

#*****************************************************************************80
#
## R8_SWAP swaps two R8's.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license. 
#
#  Modified:
#
#    04 June 2013
#
#  Author:
#
#    John Burkardt
#
#  Parameters:
#
#    Input, real X, Y, two values to interchange.
#
#    Output, real X, Y, the interchanged values.
#
  z = y
  y = x
  x = z

  return x, y

def r8_swap_test ( ):

#*****************************************************************************80
#
## R8_SWAP_TEST tests R8_SWAP.
#
#  Licensing:
#
#    This code is distributed under the GNU LGPL license.
#
#  Modified:
#
#    26 July 2014
#
#  Author:
#
#    John Burkardt
#
  import platform

  print ( '' )
  print ( 'R8_SWAP_TEST' )
  print ( '  Python version: %s' % ( platform.python_version ( ) ) )
  print ( '  R8_SWAP swaps two reals.' )

  x = 1.0
  y = 3.14159

  print ( '' )
  print ( '  Before swapping:' )
  print ( '' )
  print ( '    X = %f' % ( x ) )
  print ( '    Y = %f' % ( y ) )

  x, y = r8_swap ( x, y )

  print ( '' )
  print ( '  After swapping:' )
  print ( '' )
  print ( '    X = %f' % ( x ) )
  print ( '    Y = %f' % ( y ) )
#
#  Terminate.
#
  print ( '' )
  print ( 'R8_SWAP_TEST' )
  print ( '  Normal end of execution.' )
  return

if ( __name__ == '__main__' ):
  from timestamp import timestamp
  timestamp ( ) 
  r8_swap_test ( )
  timestamp ( )