program main

!*****************************************************************************80
!
!! cycle_floyd_test() tests cycle_floyd().
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    17 June 2012
!
!  Author:
!
!    John Burkardt
!
  implicit none

  call timestamp ( )
  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'cycle_floyd_test():'
  write ( *, '(a)' ) '  Rortran90 version'
  write ( *, '(a)' ) '  Test cycle_floyd().'

  call test01 ( )
  call test02 ( )
  call test03 ( )
  call test04 ( )
  call test05 ( )
!
!  Terminate.
!
  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'CYCLE_FLOYD_TEST():'
  write ( *, '(a)' ) '  Normal end of execution.'
  write ( *, '(a)' ) ' '
  call timestamp ( )

  stop 0
end
subroutine test01 ( )

!*****************************************************************************80
!
!! TEST01 tests CYCLE_FLOYD for a tiny example.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    14 June 2012
!
!  Author:
!
!    John Burkardt
!
  implicit none

  integer, external :: f1
  integer lam
  integer mu
  integer x0

  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'TEST01'
  write ( *, '(a)' ) '  Test CYCLE_FLOYD on F1().'
  write ( *, '(a)' ) '  f1(0) = 6.'
  write ( *, '(a)' ) '  f1(1) = 6.'
  write ( *, '(a)' ) '  f1(2) = 0.'
  write ( *, '(a)' ) '  f1(3) = 1.'
  write ( *, '(a)' ) '  f1(4) = 4.'
  write ( *, '(a)' ) '  f1(5) = 3.'
  write ( *, '(a)' ) '  f1(6) = 3.'
  write ( *, '(a)' ) '  f1(7) = 4.'
  write ( *, '(a)' ) '  f1(8) = 0.'

  x0 = 2
  write ( *, '(a)' ) ' '
  write ( *, '(a,i3)' ) '  Starting argument X0 = ', x0

  call cycle_floyd ( f1, x0, lam, mu )

  write ( *, '(a)' ) ' '
  write ( *, '(a,i3)' ) '  Reported cycle length is ', lam
  write ( *, '(a)' ) '  Expected value is 3'
  write ( *, '(a)' ) ' '
  write ( *, '(a,i3)' ) '  Reported distance to first cycle element is ', mu
  write ( *, '(a)' ) '  Expected value is 2'

  return
end
function f1 ( i )

!*****************************************************************************80
!
!! F1 is the iteration function for example 1.
!
!  Discussion:
!
!    This function has two cycles:
!
!    6, 3, 1, of length 3
!    4, of length 1
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    14 June 2012
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, integer I, the argument of the function.
!
!    Output, integer F1, the value of the function.
!
  implicit none

  integer f1
  integer, dimension ( 0 : 8 ) :: f_table = (/ &
    6, 6, 0, 1, 4, 3, 3, 4, 0 /)
  integer i

  f1 = f_table ( i )

  return
end
subroutine test02 ( )

!*****************************************************************************80
!
!! TEST02 tests CYCLE_FLOYD for F2.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    14 June 2012
!
!  Author:
!
!    John Burkardt
!
  implicit none

  integer, external :: f2
  integer lam
  integer mu
  integer x0

  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'TEST02'
  write ( *, '(a)' ) '  Test CYCLE_FLOYD for F2().'
  write ( *, '(a)' ) '  f2(i) = mod ( 22 * i + 1, 72 ).'

  x0 = 0
  write ( *, '(a)' ) ' '
  write ( *, '(a,i3)' ) '  Starting argument X0 = ', x0

  call cycle_floyd ( f2, x0, lam, mu )

  write ( *, '(a)' ) ' '
  write ( *, '(a,i3)' ) '  Reported cycle length is ', lam
  write ( *, '(a)' ) '  Expected value is 9'
  write ( *, '(a)' ) ' '
  write ( *, '(a,i3)' ) '  Reported distance to first cycle element is ', mu
  write ( *, '(a)' ) '  Expected value is 3'

  return
end
function f2 ( i )

!*****************************************************************************80
!
!! F2 is the iteration function for example 2.
!
!  Discussion:
!
!    This function has a cycle
!
!    3, 67, 35, 51, 43, 11, 27, 19, 59, of length 9
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    14 June 2012
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, integer I, the argument of the function.
!
!    Output, integer F2, the value of the function.
!
  implicit none

  integer f2
  integer i

  f2 = mod ( 22 * i + 1, 72 )

  return
end
subroutine test03 ( )

!*****************************************************************************80
!
!! TEST03 tests CYCLE_FLOYD for F3.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    14 June 2012
!
!  Author:
!
!    John Burkardt
!
  implicit none

  integer, external :: f3
  integer lam
  integer mu
  integer x0

  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'TEST03'
  write ( *, '(a)' ) '  Test CYCLE_FLOYD for F3().'
  write ( *, '(a)' ) '  f3(i) = mod ( 123 * i + 456, 100000 ).'

  x0 = 789
  write ( *, '(a)' ) ' '
  write ( *, '(a,i3)' ) '  Starting argument X0 = ', x0

  call cycle_floyd ( f3, x0, lam, mu )

  write ( *, '(a)' ) ' '
  write ( *, '(a,i8)' ) '  Reported cycle length is ', lam
  write ( *, '(a)' ) '  Expected value is 50000'
  write ( *, '(a)' ) ' '
  write ( *, '(a,i8)' ) '  Reported distance to first cycle element is ', mu
  write ( *, '(a)' ) '  Expected value is 0'

  return
end
function f3 ( i )

!*****************************************************************************80
!
!! F3 is the iteration function for example 3.
!
!  Discussion:
!
!    This function has a cycle of length 50000
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    14 June 2012
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, integer I, the argument of the function.
!
!    Output, integer F3, the value of the function.
!
  implicit none

  integer f3
  integer i

  f3 = mod ( 123 * i + 456, 1000000 )

  return
end
subroutine test04 ( )

!*****************************************************************************80
!
!! TEST04 tests CYCLE_FLOYD for F4.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    17 June 2012
!
!  Author:
!
!    John Burkardt
!
  implicit none

  integer, external :: f4
  integer lam
  integer mu
  integer x0

  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'TEST04'
  write ( *, '(a)' ) '  Test CYCLE_FLOYD for F4().'
  write ( *, '(a)' ) '  f4(i) = mod ( 31421 * i + 6927, 65536 ).'

  x0 = 1
  write ( *, '(a)' ) ' '
  write ( *, '(a,i3)' ) '  Starting argument X0 = ', x0

  call cycle_floyd ( f4, x0, lam, mu )

  write ( *, '(a)' ) ' '
  write ( *, '(a,i8)' ) '  Reported cycle length is ', lam
  write ( *, '(a)' ) '  Expected value is 65536'
  write ( *, '(a)' ) ' '
  write ( *, '(a,i8)' ) '  Reported distance to first cycle element is ', mu
  write ( *, '(a)' ) '  Expected value is 0'

  return
end
function f4 ( i )

!*****************************************************************************80
!
!! F4 is the iteration function for example 4.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    17 June 2012
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, integer I, the argument of the function.
!
!    Output, integer F4, the value of the function.
!
  implicit none

  integer f4
  integer i

  f4 = mod ( 31421 * i + 6927, 65536 )

  return
end
subroutine test05 ( )

!*****************************************************************************80
!
!! TEST05 tests CYCLE_FLOYD for F5.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    17 June 2012
!
!  Author:
!
!    John Burkardt
!
  implicit none

  integer, external :: f5
  integer i
  integer lam
  integer mu
  integer x0

  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'TEST05'
  write ( *, '(a)' ) '  Test CYCLE_FLOYD for F5().'
  write ( *, '(a)' ) '  f5(i) = mod ( 16383 * i + 1, 65536 ).'

  x0 = 1
  write ( *, '(a)' ) ' '
  write ( *, '(a,i3)' ) '  Starting argument X0 = ', x0

  call cycle_floyd ( f5, x0, lam, mu )

  write ( *, '(a)' ) ' '
  write ( *, '(a,i8)' ) '  Reported cycle length is ', lam
  write ( *, '(a)' ) '  Expected value is 8'
  write ( *, '(a)' ) ' '
  write ( *, '(a,i8)' ) '  Reported distance to first cycle element is ', mu
  write ( *, '(a)' ) '  Expected value is 0'

  i = 0
  x0 = 1
  write ( *, * ) i, x0
  do i = 1, 10
    x0 = f5 ( x0 )
    write ( *, * ) i, x0
  end do

  return
end
function f5 ( i )

!*****************************************************************************80
!
!! F5 is the iteration function for example 5.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    17 June 2012
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, integer I, the argument of the function.
!
!    Output, integer F5, the value of the function.
!
  implicit none

  integer f5
  integer i

  f5 = mod ( 16383 * i + 1, 65536 )

  return
end
subroutine timestamp ( )

!*****************************************************************************80
!
!! timestamp() prints the current YMDHMS date as a time stamp.
!
!  Example:
!
!    31 May 2001   9:45:54.872 AM
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    06 August 2005
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    None
!
  implicit none

  character ( len = 8 ) ampm
  integer d
  integer h
  integer m
  integer mm
  character ( len = 9 ), parameter, dimension(12) :: month = (/ &
    'January  ', 'February ', 'March    ', 'April    ', &
    'May      ', 'June     ', 'July     ', 'August   ', &
    'September', 'October  ', 'November ', 'December ' /)
  integer n
  integer s
  integer values(8)
  integer y

  call date_and_time ( values = values )

  y = values(1)
  m = values(2)
  d = values(3)
  h = values(5)
  n = values(6)
  s = values(7)
  mm = values(8)

  if ( h < 12 ) then
    ampm = 'AM'
  else if ( h == 12 ) then
    if ( n == 0 .and. s == 0 ) then
      ampm = 'Noon'
    else
      ampm = 'PM'
    end if
  else
    h = h - 12
    if ( h < 12 ) then
      ampm = 'PM'
    else if ( h == 12 ) then
      if ( n == 0 .and. s == 0 ) then
        ampm = 'Midnight'
      else
        ampm = 'AM'
      end if
    end if
  end if

  write ( *, '(i2,1x,a,1x,i4,2x,i2,a1,i2.2,a1,i2.2,a1,i3.3,1x,a)' ) &
    d, trim ( month(m) ), y, h, ':', n, ':', s, '.', mm, trim ( ampm )

  return
end