program main

c*********************************************************************72
c
cc sine_integral_test() tests sine_integral().
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    19 November 2024
c
c  Author:
c
c    John Burkardt
c
      implicit none

      call timestamp ( )
      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) 'sine_integral_test():'
      write ( *, '(a)' ) '  Fortran77 version'
      write ( *, '(a)' ) '  Test sine_integral().'

      call ci_test ( )
      call si_test ( )
c
c  Terminate.
c
      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) 'sine_integral_test():'
      write ( *, '(a)' ) '  Normal end of execution.'
      write ( *, '(a)' ) ' '
      call timestamp ( )

      stop 0
      end
      subroutine ci_test ( )

c*********************************************************************72
c
cc ci_test() tests ci().
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    26 March 2025
c
c  Author:
c
c    John Burkardt
c
      implicit none

      double precision fx1
      double precision fx2
      integer n_data
      double precision si
      double precision x

      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) 'ci_test():'
      write ( *, '(a)' ) 
     &  '  ci() evaluates the Cosine Integral function CI(X).'
      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) '          X           CI(X)'
      write ( *, '(a)' ) ' '

      n_data = 0

      do

        call ci_values ( n_data, x, fx1 )

        if ( n_data == 0 ) then
          exit
        end if

        call cisi ( x, fx2, si )

        write ( *, '(2x,g14.6,2x,g24.16,g24.16)' ) x, fx1, fx2

      end do

      return
      end
      subroutine ci_values ( n_data, x, fx )

c*********************************************************************72
c
cc ci_values() returns some values of the cosine integral function.
c
c  Discussion:
c
c    The cosine integral is defined by
c
c      CI(X) = - integral ( X <= T < +oo ) ( cos ( T ) ) / T  dT
c
c    In Mathematica, the function can be evaluated by:
c
c      CosIntegral(x)
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    21 March 2007
c
c  Author:
c
c    John Burkardt
c
c  Reference:
c
c    Milton Abramowitz, Irene Stegun,
c    Handbook of Mathematical Functions,
c    National Bureau of Standards, 1964,
c    ISBN: 0-486-61272-4,
c    LC: QA47.A34.
c
c    Stephen Wolfram,
c    The Mathematica Book,
c    Fourth Edition,
c    Cambridge University Press, 1999,
c    ISBN: 0-521-64314-7,
c    LC: QA76.95.W65.
c
c  Parameters:
c
c    Input/output, integer N_DATA.  The user sets N_DATA to 0 before the
c    first call.  On each call, the routine increments N_DATA by 1, and
c    returns the corresponding data; when there is no more data, the
c    output value of N_DATA will be 0 again.
c
c    Output, double precision X, the argument of the function.
c
c    Output, double precision FX, the value of the function.
c
      implicit none

      integer n_max
      parameter ( n_max = 16 )

      double precision fx
      double precision fx_vec(n_max)
      integer n_data
      double precision x
      double precision x_vec(n_max)

      save fx_vec
      save x_vec

      data fx_vec /
     &  -0.1777840788066129D+00,
     &  -0.2227070695927976D-01,
     &   0.1005147070088978D+00,
     &   0.1982786159524672D+00,
     &   0.2760678304677729D+00,
     &   0.3374039229009681D+00,
     &   0.4204591828942405D+00,
     &   0.4620065850946773D+00,
     &   0.4717325169318778D+00,
     &   0.4568111294183369D+00,
     &   0.4229808287748650D+00,
     &   0.2858711963653835D+00,
     &   0.1196297860080003D+00,
     &  -0.3212854851248112D-01,
     &  -0.1409816978869304D+00,
     &  -0.1934911221017388D+00 /
      data x_vec /
     &   0.5D+00,
     &   0.6D+00,
     &   0.7D+00,
     &   0.8D+00,
     &   0.9D+00,
     &   1.0D+00,
     &   1.2D+00,
     &   1.4D+00,
     &   1.6D+00,
     &   1.8D+00,
     &   2.0D+00,
     &   2.5D+00,
     &   3.0D+00,
     &   3.5D+00,
     &   4.0D+00,
     &   4.5D+00 /

      if ( n_data .lt. 0 ) then
        n_data = 0
      end if

      n_data = n_data + 1

      if ( n_max .lt. n_data ) then
        n_data = 0
        x = 0.0D+00
        fx = 0.0D+00
      else
        x = x_vec(n_data)
        fx = fx_vec(n_data)
      end if

      return
      end
      subroutine si_test ( )

c*********************************************************************72
c
cc si_test() tests si().
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    26 March 2025
c
c  Author:
c
c    John Burkardt
c
      implicit none

      double precision ci
      double precision fx1
      double precision fx2
      integer n_data
      double precision x

      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) 'si_test():'
      write ( *, '(a)' ) 
     &  '  si() evaluates the sine integral function.'
      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) '      X            SI(X)'
      write ( *, '(a)' ) ' '

      n_data = 0

      do

        call si_values ( n_data, x, fx1 )

        if ( n_data == 0 ) then
          exit
        end if

        call cisi ( x, ci, fx2 )

        write ( *, '(2x,g14.6,2x,g24.16,g24.16)' ) x, fx1, fx2

      end do

      return
      end
      subroutine si_values ( n_data, x, fx )

c*********************************************************************72
c
cc si_values() returns some values of the sine integral function.
c
c  Discussion:
c
c    SI(X) = integral ( 0 <= T <= X ) sin ( T ) / T dt
c
c    In Mathematica, the function can be evaluated by:
c
c      SinIntegral(x)
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    25 March 2007
c
c  Author:
c
c    John Burkardt
c
c  Reference:
c
c    Milton Abramowitz, Irene Stegun,
c    Handbook of Mathematical Functions,
c    National Bureau of Standards, 1964,
c    ISBN: 0-486-61272-4,
c    LC: QA47.A34.
c
c    Stephen Wolfram,
c    The Mathematica Book,
c    Fourth Edition,
c    Cambridge University Press, 1999,
c    ISBN: 0-521-64314-7,
c    LC: QA76.95.W65.
c
c  Parameters:
c
c    Input/output, integer N_DATA.  The user sets N_DATA to 0 before the
c    first call.  On each call, the routine increments N_DATA by 1, and
c    returns the corresponding data; when there is no more data, the
c    output value of N_DATA will be 0 again.
c
c    Output, double precision X, the argument of the function.
c
c    Output, double precision FX, the value of the function.
c
      implicit none

      integer n_max
      parameter ( n_max = 16 )

      double precision fx
      double precision fx_vec(n_max)
      integer n_data
      double precision x
      double precision x_vec(n_max)

      save fx_vec
      save x_vec

      data fx_vec /
     &  0.4931074180430667D+00,
     &  0.5881288096080801D+00,
     &  0.6812222391166113D+00,
     &  0.7720957854819966D+00,
     &  0.8604707107452929D+00,
     &  0.9460830703671830D+00,
     &  0.1108047199013719D+01,
     &  0.1256226732779218D+01,
     &  0.1389180485870438D+01,
     &  0.1505816780255579D+01,
     &  0.1605412976802695D+01,
     &  0.1778520173443827D+01,
     &  0.1848652527999468D+01,
     &  0.1833125398665997D+01,
     &  0.1758203138949053D+01,
     &  0.1654140414379244D+01 /
      data x_vec /
     &   0.5D+00,
     &   0.6D+00,
     &   0.7D+00,
     &   0.8D+00,
     &   0.9D+00,
     &   1.0D+00,
     &   1.2D+00,
     &   1.4D+00,
     &   1.6D+00,
     &   1.8D+00,
     &   2.0D+00,
     &   2.5D+00,
     &   3.0D+00,
     &   3.5D+00,
     &   4.0D+00,
     &   4.5D+00 /

      if ( n_data .lt. 0 ) then
        n_data = 0
      end if

      n_data = n_data + 1

      if ( n_max .lt. n_data ) then
        n_data = 0
        x = 0.0D+00
        fx = 0.0D+00
      else
        x = x_vec(n_data)
        fx = fx_vec(n_data)
      end if

      return
      end
      subroutine timestamp ( )

c*********************************************************************72
c
cc timestamp() prints the YMDHMS date as a timestamp.
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    12 June 2014
c
c  Author:
c
c    John Burkardt
c
      implicit none

      character * ( 8 ) ampm
      integer d
      character * ( 8 ) date
      integer h
      integer m
      integer mm
      character * ( 9 ) month(12)
      integer n
      integer s
      character * ( 10 ) time
      integer y

      save month

      data month /
     &  'January  ', 'February ', 'March    ', 'April    ', 
     &  'May      ', 'June     ', 'July     ', 'August   ', 
     &  'September', 'October  ', 'November ', 'December ' /

      call date_and_time ( date, time )

      read ( date, '(i4,i2,i2)' ) y, m, d
      read ( time, '(i2,i2,i2,1x,i3)' ) h, n, s, mm

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