program main

!*****************************************************************************80
!
!! ieee_uniform_sample_test() tests ieee_uniform_sample().
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    14 December 2007
!
!  Author:
!
!    John Burkardt
!
  implicit none

  call timestamp ( )
  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'ieee_uniform_sample_test():'
  write ( *, '(a)' ) '  Fortran90 version'
  write ( *, '(a)' ) '  Test ieee_uniform_sample().'

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

  stop 0
end
subroutine test01 ( )

!*****************************************************************************80
!
!! TEST01 tests I4_SEED_ADVANCE.
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    14 December 2007
!
!  Author:
!
!    John Burkardt
!
  implicit none

  integer i4_seed_advance
  integer seed
  integer seed_new
  integer test

  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'TEST01'
  write ( *, '(a)' ) '  I4_SEED_ADVANCE advances the seed.'
  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) '  Step        SEED input       SEED output'
  write ( *, '(a)' ) ' '

  seed_new = 12345

  do test = 1, 10

    seed = seed_new
    seed_new = i4_seed_advance ( seed )

    write ( *, '(2x,i4,2x,i16,2x,i16)' ) test, seed, seed_new

  end do

  return
end
subroutine test02 ( )

!*****************************************************************************80
!
!! TEST02 tests R4_IEEE_UNIFORM.
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    14 December 2007
!
!  Author:
!
!    John Burkardt
!
  implicit none

  real r4
  real r4_ieee_uniform
  integer seed
  integer test

  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'TEST02'
  write ( *, '(a)' ) '  R4_IEEE_UNIFORM computes an IEEE uniform'
  write ( *, '(a)' ) '  real value.'
  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) '  Step        SEED input       R4 output'
  write ( *, '(a)' ) ' '

  seed = 12345

  do test = 1, 20

    r4 = r4_ieee_uniform ( seed )

    write ( *, '(2x,i4,2x,i16,2x,g14.6)' ) test, seed, r4

  end do

  return
end
subroutine test03 ( )

!*****************************************************************************80
!
!! TEST03 tests R4_IEEE_UNIFORM.
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    15 December 2007
!
!  Author:
!
!    John Burkardt
!
  implicit none

  integer, parameter :: test_num = 1024

  real b
  integer count(9)
  integer j
  real r4_ieee_uniform
  real r4vec(test_num)
  integer seed
  real t
  integer test

  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'TEST03'
  write ( *, '(a)' ) '  R4_IEEE_UNIFORM computes an IEEE uniform'
  write ( *, '(a)' ) '  real value.'
  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) '  Generate a lot of values, and count where they fall.'
  write ( *, '(a)' ) ' '
  write ( *, '(a,i8)' ) '  Number of values to generate = ', test_num
  write ( *, '(a)' ) ' '

  seed = 12345

  do test = 1, test_num

    r4vec(test) = r4_ieee_uniform ( seed )

  end do
!
!  Sign check.
!
  count(1:3) = 0

  do test = 1, test_num
    if ( r4vec(test) < 0.0E+00 ) then
      count(1) = count(1) + 1
    else if ( r4vec(test) == 0.0E+00 ) then
      count(2) = count(2) + 1
    else if ( 0.0E+00 < r4vec(test) ) then
      count(3) = count(3) + 1
    end if
  end do

  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) '  Sign check:'
  write ( *, '(a)' ) ' '
  write ( *, '(i8,a)' ) count(1), ' values less than 0'
  write ( *, '(i8,a)' ) count(2), ' values equal to 0'
  write ( *, '(i8,a)' ) count(3), ' values greater than 0.'
!
!  Exponent check.
!
  count(1) = 0

  b = 1.0E+00 / 16.0E+00**10
  t = 1.0E+00 / 16.0E+00**9

  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) '  Exponent check'
  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) '  Bottom   Top     #( B <= |X| < T )'
  write ( *, '(a)' ) ' '

  do j = 1, 25
    count(1) = 0
    do test = 1, test_num
      if ( b <= abs ( r4vec(test) ) .and. abs ( r4vec(test) ) < t ) then
        count(1) = count(1) + 1
      end if
    end do
    write ( *, * ) b, t, count(1)
    b = t
    t = 16.0E+00 * t
  end do

  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:
!
!    18 May 2013
!
!  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