program main

c*********************************************************************72
c
cc tetrahedron_analyze() reports properties of a tetrahedron.
c
c  Usage:
c
c    tetrahedron_analyze filename
c
c    where "filename" is a file containing the coordinates of the vertices.
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    21 August 2023
c
c  Author:
c
c    John Burkardt
c
      implicit none

      double precision ab(3)
      double precision ac(3)
      double precision ad(3)
      integer arg_num
      double precision bc(3)
      double precision bd(3)
      double precision cd(3)
      double precision centroid(3)
      double precision circum_center(3)
      double precision circum_radius
      double precision dihedral_angles(6)
      integer dim_num
      double precision edge_length(6)
      double precision face_angles(3,4)
      double precision face_areas(4)
      integer iarg
      integer iargc
      double precision in_center(3)
      double precision in_radius
      character ( len = 255 ) node_filename
      integer node_num
      double precision  node_xyz(3,4)
      double precision quality1
      double precision quality2
      double precision quality3
      double precision quality4
      double precision r8_pi
      parameter ( r8_pi = 3.141592653589793D+00 )
      double precision solid_angles(4)
      double precision volume

      call timestamp ( )

      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) 'tetrahedron_analyze():'
      write ( *, '(a)' ) '  FORTRAN77 version:'
      write ( *, '(a)' ) '  Determine properties of a tetrahedron.'
c
c  Get the number of command line arguments.
c
      arg_num = iargc ( )
c
c  Commandline argument #1 is the file name
c
      if ( 1 .le. arg_num ) then

        iarg = 1
        call getarg ( iarg, node_filename )

      else

        write ( *, '(a)' ) ' '
        write ( *, '(a)' ) 'tetrahedron_analyze():'
        write ( *, '(a)' ) 
     &    '  Enter the name of the node coordinate file.'

        read ( *, '(a)' ) node_filename

      end if
c
c  Read the node data.
c
      call r8mat_header_read ( node_filename, dim_num, node_num )

      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) '  Read the header of "' 
     &  // trim ( node_filename ) //'".'
      write ( *, '(a)' ) ' '
      write ( *, '(a,i8)' ) '  Spatial dimension DIM_NUM = ', dim_num
      write ( *, '(a,i8)' ) '  Number of points NODE_NUM = ', node_num

      if ( dim_num .ne. 3 ) then
        write ( *, '(a)' ) ' '
        write ( *, '(a)' ) 'tetrahedron_analyze(): Fatal error!'
        write ( *, '(a)' ) '  Dataset must have spatial dimension 3.'
        stop
      end if

      if ( node_num .ne. 4 ) then
        write ( *, '(a)' ) ' '
        write ( *, '(a)' ) 'tetrahedron_analyze(): Fatal error!'
        write ( *, '(a)' ) '  Dataset must have 4 nodes.'
        stop
      end if

      call r8mat_data_read ( node_filename, dim_num, node_num, 
     &  node_xyz )

      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) '  Read the data in "' 
     &  // trim ( node_filename ) //'".'

      call r8mat_transpose_print ( dim_num, node_num, node_xyz, 
     &  '  Node coordinates:' )
c
c  CENTROID
c
      call tetrahedron_centroid ( node_xyz, centroid )

      write ( *, '(a)' ) ' '
      write ( *, '(a,3g14.6)' ) '  CENTROID: ', centroid(1:3)
c
c  CIRCUMSPHERE
c
      call tetrahedron_circumsphere ( node_xyz, circum_radius, 
     &  circum_center )

      write ( *, '(a)' ) ' '
      write ( *, '(a,g14.6)' ) '  CIRCUM_RADIUS = ', circum_radius
      write ( *, '(a,3g14.6)' ) '  CIRCUM_CENTER: ', circum_center(1:3)
c
c  DIHEDRAL ANGLES
c
      call tetrahedron_dihedral_angles ( node_xyz, dihedral_angles )

      call r8vec_print ( 6, dihedral_angles, 
     &  '  DIHEDRAL_ANGLES (radians)' )

      dihedral_angles(1:6) = dihedral_angles(1:6) * 180.0D+00 / r8_pi

      call r8vec_print ( 6, dihedral_angles, 
     &  '  DIHEDRAL_ANGLES (degrees)' )
c
c  EDGES
c
      call tetrahedron_edges ( node_xyz, ab, ac, ad, bc, bd, cd )

      write ( *, '(a)' ) ''
      call r8vec_transpose_print ( 3, ab, '  EDGE AB:' )
      call r8vec_transpose_print ( 3, ac, '  EDGE AC:' )
      call r8vec_transpose_print ( 3, ad, '  EDGE AD:' )
      call r8vec_transpose_print ( 3, bc, '  EDGE BC:' )
      call r8vec_transpose_print ( 3, bd, '  EDGE BD:' )
      call r8vec_transpose_print ( 3, cd, '  EDGE CD:' )
c
c  EDGE LENGTHS
c
      call tetrahedron_edge_length ( node_xyz, edge_length )

      call r8vec_print ( 6, edge_length, '  EDGE_LENGTHS' )
c
c  FACE ANGLES
c
      call tetrahedron_face_angles ( node_xyz, face_angles )

      call r8mat_transpose_print ( 3, 4, face_angles, 
     &  '  FACE_ANGLES (radians)' )

      face_angles(1:3,1:4) = face_angles(1:3,1:4) * 180.0D+00 / r8_pi

      call r8mat_transpose_print ( 3, 4, face_angles, 
     &  '  FACE_ANGLES (degrees)' )
c
c  FACE AREAS
c
      call tetrahedron_face_areas ( node_xyz, face_areas )

      call r8vec_print ( 4, face_areas, '  FACE_AREAS' )
c
c  INSPHERE
c
      call tetrahedron_insphere ( node_xyz, in_radius, in_center )

      write ( *, '(a)' ) ' '
      write ( *, '(a,g14.6)' ) '  IN_RADIUS = ', in_radius
      write ( *, '(a,3g14.6)' ) '  IN_CENTER: ', in_center(1:3)
c
c  QUALITY1
c
      call tetrahedron_quality1 ( node_xyz, quality1 )

      write ( *, '(a)' ) ' '
      write ( *, '(a,g14.6)' ) '  QUALITY1 = ', quality1
c
c  QUALITY2
c
      call tetrahedron_quality2 ( node_xyz, quality2 )

      write ( *, '(a)' ) ' '
      write ( *, '(a,g14.6)' ) '  QUALITY2 = ', quality2
c
c  QUALITY3
c
      call tetrahedron_quality3 ( node_xyz, quality3 )

      write ( *, '(a)' ) ' '
      write ( *, '(a,g14.6)' ) '  QUALITY3 = ', quality3
c
c  QUALITY4
c
      call tetrahedron_quality4 ( node_xyz, quality4 )

      write ( *, '(a)' ) ' '
      write ( *, '(a,g14.6)' ) '  QUALITY4 = ', quality4
c
c  SOLID ANGLES
c
      call tetrahedron_solid_angles ( node_xyz, solid_angles )

      call r8vec_print ( 4, solid_angles, 
     &  '  SOLID_ANGLES (steradians)' )
c
c  VOLUME
c
      call tetrahedron_volume ( node_xyz, volume )

      write ( *, '(a)' ) ' '
      write ( *, '(a,g14.6)' ) '  VOLUME = ', volume
c
c  Terminate.
c
      write ( *, '(a)' ) ' '
      write ( *, '(a)' ) 'tetrahedron_analyze():'
      write ( *, '(a)' ) '  Normal end of execution.'
      write ( *, '(a)' ) ' '
      call timestamp ( )

      stop
      end
      subroutine ch_cap ( ch )

c*********************************************************************72
c
cc ch_cap() capitalizes a single character.
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    03 January 2007
c
c  Author:
c
c    John Burkardt
c
c  Parameters:
c
c    Input/output, character CH, the character to capitalize.
c
      implicit none

      character ch
      integer itemp

      itemp = ichar ( ch )

      if ( 97 .le. itemp .and. itemp .le. 122 ) then
        ch = char ( itemp - 32 )
      end if

      return
      end
      function ch_eqi ( c1, c2 )

c*********************************************************************72
c
cc CH_EQI is a case insensitive comparison of two characters for equality.
c
c  Example:
c
c    CH_EQI ( 'A', 'a' ) is TRUE.
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    03 January 2007
c
c  Author:
c
c    John Burkardt
c
c  Parameters:
c
c    Input, character C1, C2, the characters to compare.
c
c    Output, logical CH_EQI, the result of the comparison.
c
      implicit none

      character c1
      character c1_cap
      character c2
      character c2_cap
      logical ch_eqi

      c1_cap = c1
      c2_cap = c2

      call ch_cap ( c1_cap )
      call ch_cap ( c2_cap )

      if ( c1_cap .eq. c2_cap ) then
        ch_eqi = .true.
      else
        ch_eqi = .false.
      end if

      return
      end
      subroutine ch_to_digit ( c, digit )

c*********************************************************************72
c
cc CH_TO_DIGIT returns the integer value of a base 10 digit.
c
c  Example:
c
c     C   DIGIT
c    ---  -----
c    '0'    0
c    '1'    1
c    ...  ...
c    '9'    9
c    ' '    0
c    'X'   -1
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    04 August 1999
c
c  Author:
c
c    John Burkardt
c
c  Parameters:
c
c    Input, character C, the decimal digit, '0' through '9' or blank
c    are legal.
c
c    Output, integer DIGIT, the corresponding integer value.  If C was
c    'illegal', then DIGIT is -1.
c
      implicit none

      character c
      integer digit

      if ( lge ( c, '0' ) .and. lle ( c, '9' ) ) then

        digit = ichar ( c ) - 48

      else if ( c .eq. ' ' ) then

        digit = 0

      else

        digit = -1

      end if

      return
      end
      subroutine file_column_count ( input_filename, column_num )

c*********************************************************************72
c
cc file_column_count() counts the number of columns in the first line of a file.
c
c  Discussion:
c
c    The file is assumed to be a simple text file.
c
c    Most lines of the file is presumed to consist of COLUMN_NUM words,
c    separated by spaces.  There may also be some blank lines, and some
c    comment lines,
c    which have a "#" in column 1.
c
c    The routine tries to find the first non-comment non-blank line and
c    counts the number of words in that line.
c
c    If all lines are blanks or comments, it goes back and tries to analyze
c    a comment line.
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    28 April 2008
c
c  Author:
c
c    John Burkardt
c
c  Parameters:
c
c    Input, character * ( * ) INPUT_FILENAME, the name of the file.
c
c    Output, integer COLUMN_NUM, the number of columns in the file.
c
      implicit none

      integer column_num
      logical got_one
      character * ( * ) input_filename
      integer input_unit
      character * ( 255 ) line
c
c  Open the file.
c
      call get_unit ( input_unit )

      open ( unit = input_unit, file = input_filename,
     &  status = 'old', form = 'formatted', access = 'sequential' )
c
c  Read one line, but skip blank lines and comment lines.
c
      got_one = .false.

10    continue

        read ( input_unit, '(a)', err = 20 ) line

        if ( len_trim ( line ) .eq. 0 ) then
          go to 10
        end if

        if ( line(1:1) .eq. '#' ) then
          go to 10
        end if

        got_one = .true.
        go to 20

      go to 10

20    continue

      if ( .not. got_one ) then

        rewind ( input_unit )

30      continue

          read ( input_unit, '(a)', err = 40 ) line

          if ( len_trim ( line ) .eq. 0 ) then
            go to 30
          end if

          got_one = .true.
          go to 40

        go to 30

40    continue

      end if

      close ( unit = input_unit )

      if ( .not. got_one ) then
        write ( *, '(a)' ) ' '
        write ( *, '(a)' ) 'FILE_COLUMN_COUNT - Warning.'
        write ( *, '(a)' ) '  The file does not contain any data.'
        column_num = -1
        return
      end if

      call s_word_count ( line, column_num )

      return
      end
      subroutine file_row_count ( input_filename, row_num )

c*********************************************************************72
c
cc FILE_ROW_COUNT counts the number of row records in a file.
c
c  Discussion:
c
c    It does not count lines that are blank, or that begin with a
c    comment symbol '#'.
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    28 April 2008
c
c  Author:
c
c    John Burkardt
c
c  Parameters:
c
c    Input, character * ( * ) INPUT_FILENAME, the name of the input file.
c
c    Output, integer ROW_NUM, the number of rows found.
c
      implicit none

      integer bad_num
      integer comment_num
      character * ( * ) input_filename
      integer input_unit
      character * ( 255 ) line
      integer record_num
      integer row_num

      call get_unit ( input_unit )

      open ( unit = input_unit, file = input_filename,
     &  status = 'old' )

      comment_num = 0
      row_num = 0
      record_num = 0
      bad_num = 0

10    continue

        read ( input_unit, '(a)', err = 20, end = 20 ) line

        record_num = record_num + 1

        if ( line(1:1) .eq. '#' ) then
          comment_num = comment_num + 1
          go to 10
        end if

        if ( len_trim ( line ) .eq. 0 ) then
          comment_num = comment_num + 1
          go to 10
        end if

        row_num = row_num + 1

      go to 10

20    continue

      close ( unit = input_unit )

      return
      end
      subroutine get_unit ( iunit )

c*********************************************************************72
c
cc GET_UNIT returns a free FORTRAN unit number.
c
c  Discussion:
c
c    A "free" FORTRAN unit number is a value between 1 and 99 which
c    is not currently associated with an I/O device.  A free FORTRAN unit
c    number is needed in order to open a file with the OPEN command.
c
c    If IUNIT = 0, then no free FORTRAN unit could be found, although
c    all 99 units were checked (except for units 5, 6 and 9, which
c    are commonly reserved for console I/O).
c
c    Otherwise, IUNIT is a value between 1 and 99, representing a
c    free FORTRAN unit.  Note that GET_UNIT assumes that units 5 and 6
c    are special, and will never return those values.
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    02 September 2013
c
c  Author:
c
c    John Burkardt
c
c  Parameters:
c
c    Output, integer IUNIT, the free unit number.
c
      implicit none

      integer i
      integer iunit
      logical value

      iunit = 0

      do i = 1, 99

        if ( i .ne. 5 .and. i .ne. 6 .and. i .ne. 9 ) then

          inquire ( unit = i, opened = value, err = 10 )

          if ( .not. value ) then
            iunit = i
            return
          end if

        end if

10      continue

      end do

      return
      end
      subroutine r8mat_data_read ( input_filename, m, n, table )

c*********************************************************************72
c
cc r8mat_data_read() reads data from an R8MAT file.
c
c  Discussion:
c
c    An R8MAT is an array of R8's.
c
c    The file may contain more than N points, but this routine will
c    return after reading N of them.
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    28 April 2008
c
c  Author:
c
c    John Burkardt
c
c  Parameters:
c
c    Input, character * ( * ) INPUT_FILENAME, the name of the input file.
c
c    Input, integer M, the spatial dimension.
c
c    Input, integer N, the number of points.
c
c    Output, double precision TABLE(M,N), the data.
c
      implicit none

      integer m
      integer  n

      integer i
      integer ierror
      character * ( * ) input_filename
      integer input_unit
      integer j
      character * ( 255 ) line
      double precision table(m,n)
      double precision x(m)

      ierror = 0

      call get_unit ( input_unit )

      open ( unit = input_unit, file = input_filename,
     &  status = 'old' )

      j = 0

10    continue

      if ( j .lt. n ) then

        read ( input_unit, '(a)' ) line

        if ( line(1:1) .eq. '#' .or. len_trim ( line ) .eq. 0 ) then
          go to 10
        end if

        call s_to_r8vec ( line, m, x, ierror )

        if ( ierror .ne. 0 ) then
          go to 10
        end if

        j = j + 1

        do i = 1, m
          table(i,j) = x(i)
        end do

        go to 10

      end if

      close ( unit = input_unit )

      return
      end
      subroutine r8mat_header_read ( input_filename, m, n )

c*********************************************************************72
c
cc r8mat_header_read() reads the header from an R8MAT file.
c
c  Discussion:
c
c    An R8MAT is an array of R8's.
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    28 April 2008
c
c  Author:
c
c    John Burkardt
c
c  Parameters:
c
c    Input, character * ( * ) INPUT_FILENAME, the name of the input file.
c
c    Output, integer M, spatial dimension.
c
c    Output, integer N, the number of points.
c
      implicit none

      character * ( * ) input_filename
      integer m
      integer n

      call file_column_count ( input_filename, m )

      if ( m .le. 0 ) then
        write ( *, '(a)' ) ' '
        write ( *, '(a)' ) 'R8MAT_HEADER_READ - Fatal error!'
        write ( *, '(a)' ) '  There was an I/O problem while trying'
        write ( *, '(a)' ) '  to count the number of data columns in'
        write ( *, '(a,a,a)' )
     &    '  the file "', trim ( input_filename ), '".'
        stop 1
      end if

      call file_row_count ( input_filename, n )

      if ( n .le. 0 ) then
        write ( *, '(a)' ) ' '
        write ( *, '(a)' ) 'R8MAT_HEADER_READ - Fatal error!'
        write ( *, '(a)' ) '  There was an I/O problem while trying'
        write ( *, '(a)' ) '  to count the number of data rows in'
        write ( *, '(a,a,a)' )
     &    '  the file "', trim ( input_filename ), '".'
        stop 1
      end if

      return
      end
      subroutine s_to_r8 ( s, dval, ierror, length )

c*********************************************************************72
c
cc S_TO_R8() reads an R8 from a string.
c
c  Discussion:
c
c    The routine will read as many characters as possible until it reaches
c    the end of the string, or encounters a character which cannot be
c    part of the number.
c
c    Legal input is:
c
c       1 blanks,
c       2 '+' or '-' sign,
c       2.5 blanks
c       3 integer part,
c       4 decimal point,
c       5 fraction part,
c       6 'E' or 'e' or 'D' or 'd', exponent marker,
c       7 exponent sign,
c       8 exponent integer part,
c       9 exponent decimal point,
c      10 exponent fraction part,
c      11 blanks,
c      12 final comma or semicolon,
c
c    with most quantities optional.
c
c  Example:
c
c    S                 DVAL
c
c    '1'               1.0
c    '     1   '       1.0
c    '1A'              1.0
c    '12,34,56'        12.0
c    '  34 7'          34.0
c    '-1E2ABCD'        -100.0
c    '-1X2ABCD'        -1.0
c    ' 2E-1'           0.2
c    '23.45'           23.45
c    '-4.2E+2'         -420.0
c    '17d2'            1700.0
c    '-14e-2'         -0.14
c    'e2'              100.0
c    '-12.73e-9.23'   -12.73 * 10.0^(-9.23)
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    28 April 2008
c
c  Author:
c
c    John Burkardt
c
c  Parameters:
c
c    Input, character * ( * ) S, the string containing the
c    data to be read.  Reading will begin at position 1 and
c    terminate at the end of the string, or when no more
c    characters can be read to form a legal real.  Blanks,
c    commas, or other nonnumeric data will, in particular,
c    cause the conversion to halt.
c
c    Output, double precision DVAL, the value read from the string.
c
c    Output, integer IERROR, error flag.
c    0, no errors occurred.
c    1, 2, 6 or 7, the input number was garbled.  The
c    value of IERROR is the last type of input successfully
c    read.  For instance, 1 means initial blanks, 2 means
c    a plus or minus sign, and so on.
c
c    Output, integer LENGTH, the number of characters read
c    to form the number, including any terminating
c    characters such as a trailing comma or blanks.
c
      implicit none

      logical ch_eqi
      character c
      double precision dval
      integer ierror
      integer ihave
      integer isgn
      integer iterm
      integer jbot
      integer jsgn
      integer jtop
      integer length
      integer nchar
      integer ndig
      double precision rbot
      double precision rexp
      double precision rtop
      character * ( * ) s

      nchar = len_trim ( s )

      ierror = 0
      dval = 0.0D+00
      length = -1
      isgn = 1
      rtop = 0
      rbot = 1
      jsgn = 1
      jtop = 0
      jbot = 1
      ihave = 1
      iterm = 0

10    continue

        length = length + 1

        if ( nchar .lt. length + 1 ) then
          go to 20
        end if

        c = s(length+1:length+1)
c
c  Blank character.
c
        if ( c .eq. ' ' ) then

          if ( ihave .eq. 2 ) then

          else if ( ihave .eq. 6 .or. ihave .eq. 7 ) then
            iterm = 1
          else if ( 1 .lt. ihave ) then
            ihave = 11
          end if
c
c  Comma.
c
        else if ( c .eq. ',' .or. c .eq. ';' ) then

          if ( ihave .ne. 1 ) then
            iterm = 1
            ihave = 12
            length = length + 1
          end if
c
c  Minus sign.
c
        else if ( c .eq. '-' ) then

          if ( ihave .eq. 1 ) then
            ihave = 2
            isgn = -1
          else if ( ihave .eq. 6 ) then
            ihave = 7
            jsgn = -1
          else
            iterm = 1
          end if
c
c  Plus sign.
c
        else if ( c .eq. '+' ) then

          if ( ihave .eq. 1 ) then
            ihave = 2
          else if ( ihave .eq. 6 ) then
            ihave = 7
          else
            iterm = 1
          end if
c
c  Decimal point.
c
        else if ( c .eq. '.' ) then

          if ( ihave .lt. 4 ) then
            ihave = 4
          else if ( 6 .le. ihave .and. ihave .le. 8 ) then
            ihave = 9
          else
            iterm = 1
          end if
c
c  Scientific notation exponent marker.
c
        else if ( ch_eqi ( c, 'E' ) .or. ch_eqi ( c, 'D' ) ) then

          if ( ihave .lt. 6 ) then
            ihave = 6
          else
            iterm = 1
          end if
c
c  Digit.
c
        else if ( ihave .lt. 11 .and. lle ( '0', c )
     &    .and. lle ( c, '9' ) ) then

          if ( ihave .le. 2 ) then
            ihave = 3
          else if ( ihave .eq. 4 ) then
            ihave = 5
          else if ( ihave .eq. 6 .or. ihave .eq. 7 ) then
            ihave = 8
          else if ( ihave .eq. 9 ) then
            ihave = 10
          end if

          call ch_to_digit ( c, ndig )

          if ( ihave .eq. 3 ) then
            rtop = 10.0D+00 * rtop + dble ( ndig )
          else if ( ihave .eq. 5 ) then
            rtop = 10.0D+00 * rtop + dble ( ndig )
            rbot = 10.0D+00 * rbot
          else if ( ihave .eq. 8 ) then
            jtop = 10 * jtop + ndig
          else if ( ihave .eq. 10 ) then
            jtop = 10 * jtop + ndig
            jbot = 10 * jbot
          end if
c
c  Anything else is regarded as a terminator.
c
        else
          iterm = 1
        end if
c
c  If we haven't seen a terminator, and we haven't examined the
c  entire string, go get the next character.
c
        if ( iterm .eq. 1 ) then
          go to 20
        end if

        go to 10

20    continue
c
c  If we haven't seen a terminator, and we have examined the
c  entire string, then we're done, and LENGTH is equal to NCHAR.
c
      if ( iterm .ne. 1 .and. length+1 .eq. nchar ) then
        length = nchar
      end if
c
c  Number seems to have terminated.  Have we got a legal number?
c  Not if we terminated in states 1, 2, 6 or 7.
c
      if ( ihave .eq. 1 .or. ihave .eq. 2 .or.
     &     ihave .eq. 6 .or. ihave .eq. 7 ) then
        ierror = ihave
        write ( *, '(a)' ) ' '
        write ( *, '(a)' ) 'S_TO_R8 - Serious error!'
        write ( *, '(a)' ) '  Illegal or nonnumeric input:'
        write ( *, '(a,a)' ) '    ', s
        return
      end if
c
c  Number seems OK.  Form it.
c
      if ( jtop .eq. 0 ) then
        rexp = 1.0D+00
      else
        if ( jbot .eq. 1 ) then
          rexp = 10.0D+00 ** ( jsgn * jtop )
        else
          rexp = 10.0D+00 ** ( dble ( jsgn * jtop ) / dble ( jbot ) )
        end if
      end if

      dval = dble ( isgn ) * rexp * rtop / rbot

      return
      end
      subroutine s_to_r8vec ( s, n, rvec, ierror )

c*********************************************************************72
c
cc S_TO_R8VEC reads an R8VEC from a string.
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    28 April 2008
c
c  Author:
c
c    John Burkardt
c
c  Parameters:
c
c    Input, character * ( * ) S, the string to be read.
c
c    Input, integer N, the number of values expected.
c
c    Output, double precision RVEC(N), the values read from the string.
c
c    Output, integer IERROR, error flag.
c    0, no errors occurred.
c    -K, could not read data for entries -K through N.
c
      implicit none

      integer  n

      integer i
      integer ierror
      integer ilo
      integer lchar
      double precision rvec(n)
      character * ( * ) s

      i = 0
      ierror = 0
      ilo = 1

10    continue

      if ( i .lt. n ) then

        i = i + 1

        call s_to_r8 ( s(ilo:), rvec(i), ierror, lchar )

        if ( ierror .ne. 0 ) then
          ierror = -i
          go to 20
        end if

        ilo = ilo + lchar

        go to 10

      end if

20    continue

      return
      end
      subroutine s_word_count ( s, nword )

c*********************************************************************72
c
cc S_WORD_COUNT counts the number of "words" in a string.
c
c  Licensing:
c
c    This code is distributed under the MIT license.
c
c  Modified:
c
c    28 April 2008
c
c  Author:
c
c    John Burkardt
c
c  Parameters:
c
c    Input, character * ( * ) S, the string to be examined.
c
c    Output, integer NWORD, the number of "words" in the string.
c    Words are presumed to be separated by one or more blanks.
c
      implicit none

      logical blank
      integer i
      integer lens
      integer nword
      character * ( * ) s

      nword = 0
      lens = len ( s )

      if ( lens .le. 0 ) then
        return
      end if

      blank = .true.

      do i = 1, lens

        if ( s(i:i) .eq. ' ' ) then
          blank = .true.
        else if ( blank ) then
          nword = nword + 1
          blank = .false.
        end if

      end do

      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