subroutine ch_cap ( ch )

!*****************************************************************************80
!
!! ch_cap() capitalizes a single character.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    30 November 1998
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input/output, character CH, the character to capitalize.
!
  implicit none

  character ch
  integer itemp

  itemp = ichar ( ch )

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

  return
end
subroutine get_unit ( iunit )

!*****************************************************************************80
!
!! get_unit() returns a free FORTRAN unit number.
!
!  Discussion:
!
!    A "free" FORTRAN unit number is a value between 1 and 99 which
!    is not currently associated with an I/O device.  A free FORTRAN unit
!    number is needed in order to open a file with the OPEN command.
!
!    If IUNIT = 0, then no free FORTRAN unit could be found, although
!    all 99 units were checked (except for units 5, 6 and 9, which
!    are commonly reserved for console I/O).
!
!    Otherwise, IUNIT is a value between 1 and 99, representing a
!    free FORTRAN unit.  Note that GET_UNIT assumes that units 5 and 6
!    are special, and will never return those values.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    26 October 2008
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Output, integer IUNIT, the free unit number.
!
  implicit none

  integer i
  integer ios
  integer iunit
  logical lopen
 
  iunit = 0
 
  do i = 1, 99
 
    if ( i /= 5 .and. i /= 6 .and. i /= 9 ) then

      inquire ( unit = i, opened = lopen, iostat = ios )
 
      if ( ios == 0 ) then
        if ( .not. lopen ) then
          iunit = i
          return
        end if
      end if

    end if
 
  end do

  return
end
subroutine getint ( done, ierror, inunit, ival, string )

!*****************************************************************************80
!
!! getint() reads an integer from a file.
!
!  Discussion:
!
!    The file, or at least the part read by GETINT, is assumed to
!    contain nothing but integers.  These integers may be separated
!    by spaces, or appear on separate lines.  Comments, which begin
!    with "#" and extend to the end of the line, may appear anywhere.
!
!    Each time GETINT is called, it tries to read the next integer
!    it can find.  It remembers where it was in the current line
!    of text.
!
!    The user should open a text file on FORTRAN unit INUNIT,
!    set STRING = ' ' and DONE = TRUE.  The GETINT routine will take
!    care of reading in a new STRING as necessary, and extracting
!    as many integers as possible from the line of text before 
!    reading in the next line.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    07 October 2000
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input/output, logical DONE.
!    On input, if this is the first call, or the user has changed
!    STRING, then set DONE = TRUE.
!    On output, if there is no more data to be read from STRING,
!    then DONE is TRUE.
!
!    Output, integer IERROR, error flag.
!    0, no error occurred.
!    1, an error occurred while trying to read the integer.
!
!    Input, integer INUNIT, the FORTRAN unit from which to read.
!
!    Output, integer IVAL, the integer that was read.
!
!    Input/output, character ( len = * ) STRING, the text of the most recently 
!    read line of the file.
!
  implicit none

  logical done
  integer i
  integer ierror
  integer inunit
  integer ios
  integer ival
  integer last
  character ( len = * ) string
  character ( len = 255 ) word

  do

    call word_next_rd ( string, word, done )

    if ( .not. done ) then
      exit
    end if

    read ( inunit, '(a)', iostat = ios ) string

    if ( ios /= 0 ) then
      ierror = 1
      return
    end if

    i = index ( string, '#' )
    if ( i /= 0 ) then
      string(i:) = ' '
    end if

  end do

  call s_to_i4 ( word, ival, ierror, last )

  if ( ierror /= 0 ) then
    write ( *, '(a)' ) ' '
    write ( *, '(a)' ) 'GETINT - Fatal error!'
    write ( *, '(a)' ) '  Error trying to convert string to integer.'
    stop
  end if

  return
end
subroutine gray_median_news ( m, n, gray, gray2 )

!*****************************************************************************80
!
!! gray_median_news() uses a median NEWS filter on a gray scale image.
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    27 August 2011
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, integer M, N, the number of rows and columns of pixels.
!
!    Input, integer GRAY(M,N), the noisy grayscale data.
!
!    Output, integer GRAY2(M,N), the grayscale data for the 
!    filtered image.
!
  implicit none

  integer m
  integer n

  integer gray(m,n)
  integer gray2(m,n)
  integer i
  integer j
  integer p(5)
!
!  Process the main part of the image:
!
  do i = 2, m - 1
    do j = 2, n - 1
      p(1) = gray(i-1,j  )
      p(2) = gray(i+1,j  )
      p(3) = gray(i  ,j+1)
      p(4) = gray(i  ,j-1)
      p(5) = gray(i  ,j  )
      call i4vec_median ( 5, p, gray2(i,j) )
    end do
  end do
!
!  Process the four borders.
!  Get an odd number of data points, 
!
  do i = 2, m - 1
    j = 1
    p(1) = gray(i-1,j  )
    p(2) = gray(i+1,j  )
    p(3) = gray(i  ,j  )
    p(4) = gray(i  ,j+1)
    p(5) = gray(i  ,j+2)
    call i4vec_median ( 5, p, gray2(i,j) )

    j = n
    p(1) = gray(i-1,j  )
    p(2) = gray(i+1,j  )
    p(3) = gray(i  ,j-2)
    p(4) = gray(i  ,j-1)
    p(5) = gray(i  ,j  )
    call i4vec_median ( 5, p, gray2(i,j) )
  end do

  do j = 2, n - 1
    i = 1
    p(1) = gray(i  ,j  )
    p(2) = gray(i+1,j  )
    p(3) = gray(i+2,j  )
    p(4) = gray(i  ,j-1)
    p(5) = gray(i  ,j+1)
    call i4vec_median ( 5, p, gray2(i,j) )

    i = m - 1
    p(1) = gray(i-2,j  )
    p(2) = gray(i-1,j  )
    p(3) = gray(i  ,j  )
    p(4) = gray(i  ,j-1)
    p(5) = gray(i  ,j+1)
    call i4vec_median ( 5, p, gray2(i,j) )
  end do
!
!  Process the four corners.
!
  i = 1
  j = 1
  p(1) = gray(i+1,j  )
  p(2) = gray(i  ,j  )
  p(3) = gray(i  ,j+1)
  call i4vec_median ( 3, p, gray2(i,j) )

  i = 1
  j = n
  p(1) = gray(i+1,j  )
  p(2) = gray(i  ,j  )
  p(3) = gray(i  ,j-1)
  call i4vec_median ( 3, p, gray2(i,j) )

  i = m
  j = 1
  p(1) = gray(i-1,j  )
  p(2) = gray(i  ,j  )
  p(3) = gray(i  ,j+1)
  call i4vec_median ( 3, p, gray2(i,j) )

  i = m - 1
  j = n - 1
  p(1) = gray(i-1,j  )
  p(2) = gray(i  ,j  )
  p(3) = gray(i  ,j-1)
  call i4vec_median ( 3, p, gray2(i,j) )

  return
end
subroutine i4vec_frac ( n, a, k, frac )

!*****************************************************************************80
!
!! i4vec_frac() searches for the K-th smallest element in an I4VEC.
!
!  Discussion:
!
!    An I4VEC is a vector of I4's.
!
!    Hoare's algorithm is used.
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    30 September 2009
!
!  Author:
!
!    This version by John Burkardt
!
!  Parameters:
!
!    Input, integer N, the number of elements of A.
!
!    Input/output, integer A(N), array to search.  On output,
!    the elements of A have been somewhat rearranged.
!
!    Input, integer K, the fractile to be sought.  If K = 1, the
!    minimum entry is sought.  If K = N, the maximum is sought.
!    Other values of K search for the entry which is K-th in size.
!    K must be at least 1, and no greater than N.
!
!    Output, integer FRAC, the value of the K-th fractile of A.
!
  implicit none

  integer n

  integer a(n)
  integer frac
  integer i
  integer iryt
  integer ix
  integer j
  integer k
  integer left
  integer t

  if ( n <= 0 ) then
    write ( *, '(a)' ) ' '
    write ( *, '(a)' ) 'I4VEC_FRAC  - Fatal error!'
    write ( *, '(a,i8)' ) '  Illegal nonpositive value of N = ', n
    stop
  end if

  if ( k <= 0 ) then
    write ( *, '(a)' ) ' '
    write ( *, '(a)' ) 'I4VEC_FRAC  - Fatal error!'
    write ( *, '(a,i8)' ) '  Illegal nonpositive value of K = ', k
    stop
  end if

  if ( n < k ) then
    write ( *, '(a)' ) ' '
    write ( *, '(a)' ) 'I4VEC_FRAC  - Fatal error!'
    write ( *, '(a,i8)' ) '  Illegal N < K, K = ', k
    stop
  end if

  left = 1
  iryt = n

  do

    if ( iryt <= left ) then
      frac = a(k)
      exit
    end if

    ix = a(k)
    i = left
    j = iryt

    do

      if ( j < i ) then

        if ( j < k ) then
          left = i
        end if

        if ( k < i ) then
          iryt = j
        end if

        exit

      end if
!
!  Find I so that IX <= A(I).
!
      do while ( a(i) < ix )
        i = i + 1
      end do
!
!  Find J so that A(J) <= IX.
!
      do while ( ix < a(j) )
        j = j - 1
      end do

      if ( i <= j ) then

        t    = a(i)
        a(i) = a(j)
        a(j) = t

        i = i + 1
        j = j - 1

      end if

    end do

  end do

  return
end
subroutine i4vec_median ( n, a, median )

!*****************************************************************************80
!
!! i4vec_median() returns the median of an unsorted I4VEC.
!
!  Discussion:
!
!    An I4VEC is a vector of I4's.
!
!    Hoare's algorithm is used.  The values of the vector are
!    rearranged by this routine.
!
!  Licensing:
!
!    This code is distributed under the MIT license.
!
!  Modified:
!
!    18 September 2000
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, integer N, the number of elements of A.
!
!    Input/output, integer A(N), the array to search.  On output,
!    the order of the elements of A has been somewhat changed.
!
!    Output, integer MEDIAN, the value of the median of A.
!
  implicit none

  integer n

  integer a(n)
  integer k
  integer median

  k = ( n + 1 ) / 2

  call i4vec_frac ( n, a, k, median )

  return
end
subroutine pgma_read_data ( file_in_unit, row_num, col_num, g )

!*****************************************************************************80
!
!! pgma_read_data() reads the data in an ASCII PGM file.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    04 June 2010
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, integer FILE_IN_UNIT, the unit number of the file.
!
!    Input, integer ROW_NUM, COL_NUM, the number of rows and 
!    columns of data.
!
!    Output, integer G(ROW_NUM,COL_NUM), the gray data.
!
  implicit none

  integer col_num
  integer row_num

  logical done
  integer file_in_unit
  integer g(row_num,col_num)
  integer i
  integer ierror
  integer j
  character ( len = 255 ) string

  ierror = 0
  done = .true.
  string = ' '

  do i = 1, row_num
    do j = 1, col_num

      call getint ( done, ierror, file_in_unit, g(i,j), string )

      if ( ierror /= 0 ) then
        close ( unit = file_in_unit )
        write ( *, '(a)' ) ' '
        write ( *, '(a)' ) 'PGMA_READ_DATA - Fatal error!'
        write ( *, '(a)' ) '  Problem reading G data.'
        stop
      end if

    end do
  end do

  return
end
subroutine pgma_read_header ( file_in_unit, row_num, col_num, g_max )

!*****************************************************************************80
!
!! pgma_read_header() reads the header of an ASCII PGM file.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    04 June 2010
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, integer FILE_IN_UNIT, the unit number of the file.
!
!    Output, integer ROW_NUM, COL_NUM, the number of rows and 
!    columns of data.
!
!    Output, integer G_MAX, the maximum gray value.
!
  implicit none

  logical done
  integer file_in_unit
  integer ierror
  integer ios
  character ( len = 2 ) magic
  integer g_max
  integer col_num
  integer row_num
  logical s_eqi
  character ( len = 255 ) string
!
!  Read the first line of data, which must begin with the magic number.
!
  read ( file_in_unit, '(a)', iostat = ios ) magic

  if ( ios /= 0 ) then
    write ( *, '(a)' ) ' '
    write ( *, '(a)' ) 'PGMA_READ_HEADER - Fatal error!'
    write ( *, '(a)' ) '  End or error while reading file.'
    ierror = 2
    stop
  end if

  if ( .not. s_eqi ( magic, 'P2' ) ) then
    ierror = 3
    write ( *, '(a)' ) ' '
    write ( *, '(a)' ) 'PGMA_READ_HEADER - Fatal error.'
    write ( *, '(a)' ) '  First two bytes are not magic number "P2".'
    write ( *, '(a)' ) '  First two bytes are: "' // magic // '".'
    stop
  end if
!
!  Now search for COL_NUM, ROW_NUM, and G_MAX.
!
  done = .true.
  string = ' '

  call getint ( done, ierror, file_in_unit, col_num, string )

  if ( ierror /= 0 ) then
    close ( unit = file_in_unit )
    ierror = 4
    write ( *, '(a)' ) ' '
    write ( *, '(a)' ) 'PGMA_READ_HEADER - Fatal error!'
    write ( *, '(a)' ) '  Problem reading COL_NUM.'
    stop
  end if

  call getint ( done, ierror, file_in_unit, row_num, string )

  if ( ierror /= 0 ) then
    ierror = 4
    close ( unit = file_in_unit )
    write ( *, '(a)' ) ' '
    write ( *, '(a)' ) 'PGMA_READ_HEADER - Fatal error!'
    write ( *, '(a)' ) '  Problem reading ROW_NUM.'
    stop
  end if

  call getint ( done, ierror, file_in_unit, g_max, string )

  if ( ierror /= 0 ) then
    ierror = 4
    close ( unit = file_in_unit )
    write ( *, '(a)' ) ' '
    write ( *, '(a)' ) 'PGMA_READ_HEADER - Fatal error!'
    write ( *, '(a)' ) '  Problem reading G_MAX.'
    stop
  end if

  return
end
subroutine pgma_write ( file_out_name, row_num, col_num, g )

!*****************************************************************************80
!
!! pgma_write() writes an ASCII PGM file.
!
!  Example:
!
!    P2
!    # feep.pgm
!    24 7
!    15
!    0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
!    0  3  3  3  3  0  0  7  7  7  7  0  0 11 11 11 11  0  0 15 15 15 15  0
!    0  3  0  0  0  0  0  7  0  0  0  0  0 11  0  0  0  0  0 15  0  0 15  0
!    0  3  3  3  0  0  0  7  7  7  0  0  0 11 11 11  0  0  0 15 15 15 15  0
!    0  3  0  0  0  0  0  7  0  0  0  0  0 11  0  0  0  0  0 15  0  0  0  0
!    0  3  0  0  0  0  0  7  7  7  7  0  0 11 11 11 11  0  0 15  0  0  0  0
!    0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0  0
!    
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    01 March 2003
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, character ( len = * ) FILE_OUT_NAME, the name of the file 
!    to which the data should be written.
!
!    Input, integer ROW_NUM, COL_NUM, the number of rows and 
!    columns of data.
!
!    Input, integer G(ROW_NUM,COL_NUM), the gray value of each 
!    pixel.  These should be nonnegative.
!
  implicit none

  integer col_num
  integer row_num

  logical, parameter :: debug = .false.
  character ( len = * ) file_out_name
  integer file_out_unit
  integer g(row_num,col_num)
  integer ios
  integer g_max
!
!  Compute the maximum color value.
!
  g_max = maxval ( g(1:row_num,1:col_num) )
!
!  Open the file.
!
  call get_unit ( file_out_unit )

  open ( unit = file_out_unit, file = file_out_name, status = 'replace', &
    form = 'formatted', access = 'sequential', iostat = ios )

  if ( ios /= 0 ) then
    write ( *, '(a)' ) ' '
    write ( *, '(a)' ) 'PGMA_WRITE - Fatal error!'
    write ( *, '(a)' ) '  Could not open the file.'
    stop
  end if
!
!  Write the header.
!
  call pgma_write_header ( file_out_name, file_out_unit, row_num, col_num, &
    g_max )
!
!  Write the data.
!
  call pgma_write_data ( file_out_unit, row_num, col_num, g )
!
!  Close the file.
!
  close ( unit = file_out_unit )
!
!  Report
!
  if ( debug ) then
    write ( *, '(a)' ) ' '
    write ( *, '(a)' ) 'PGMA_WRITE - Note:'
    write ( *, '(a)' ) '  The data was checked and written.'
    write ( *, '(a,i8)' ) '  Number of data rows ROW_NUM =    ', row_num
    write ( *, '(a,i8)' ) '  Number of data columns COL_NUM = ', col_num
    write ( *, '(a,i8)' ) '  Maximum gray value G_MAX =       ', g_max
  end if

  return
end
subroutine pgma_write_data ( file_out_unit, row_num, col_num, g )

!*****************************************************************************80
!
!! pgma_write_data() writes the data of an ASCII PGM file.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    28 February 2003
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, integer FILE_OUT_UNIT, the output file unit number.
!
!    Input, integer ROW_NUM, COL_NUM, the number of rows and 
!    columns of data.
!
!    Input, integer G(ROW_NUM,COL_NUM), the gray value of each 
!    pixel.  These should be nonnegative.
!
  implicit none

  integer col_num
  integer row_num

  integer file_out_unit
  integer g(row_num,col_num)
  integer i
  integer jhi
  integer jlo

  do i = 1, row_num
    do jlo = 1, col_num, 12
      jhi = min ( jlo + 11, col_num )
      write ( file_out_unit, '(12i5)' ) g(i,jlo:jhi)
    end do
  end do

  return
end
subroutine pgma_write_header ( file_out_name, file_out_unit, row_num, col_num, &
  g_max )

!*****************************************************************************80
!
!! pgma_write_header() writes the header of an ASCII PGM file.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    01 March 2003
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, character ( len = * ) FILE_OUT_NAME, the name of the output file.
!
!    Input, integer FILE_OUT_UNIT, the output file unit number.
!
!    Input, integer ROW_NUM, COL_NUM, the number of rows and 
!    columns of data.
!
!    Input, integer G_MAX, the maximum gray value.
!
  implicit none

  character ( len = * )  file_out_name
  integer file_out_unit
  character ( len = 2 ) :: magic = 'P2'
  integer g_max
  integer col_num
  integer row_num
!
!  Write the header.
!
  write ( file_out_unit, '(a2)' ) magic
  write ( file_out_unit, '(a)' ) '# ' // trim ( file_out_name ) &
    // ' created by PGMA_IO::PGMA_WRITE.'
  write ( file_out_unit, '(i8,2x,i8)' ) col_num, row_num
  write ( file_out_unit, '(i8)' ) g_max

  return
end
function s_eqi ( s1, s2 )

!*****************************************************************************80
!
!! s_eqi() is a case insensitive comparison of two strings for equality.
!
!  Example:
!
!    S_EQI ( 'Anjana', 'ANJANA' ) is .TRUE.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    14 April 1999
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, character ( len = * ) S1, S2, the strings to compare.
!
!    Output, logical S_EQI, the result of the comparison.
!
  implicit none

  character c1
  character c2
  integer i
  integer len1
  integer len2
  integer lenc
  logical s_eqi
  character ( len = * ) s1
  character ( len = * ) s2

  len1 = len ( s1 )
  len2 = len ( s2 )
  lenc = min ( len1, len2 )

  s_eqi = .false.

  do i = 1, lenc

    c1 = s1(i:i)
    c2 = s2(i:i)
    call ch_cap ( c1 )
    call ch_cap ( c2 )

    if ( c1 /= c2 ) then
      return
    end if

  end do

  do i = lenc + 1, len1
    if ( s1(i:i) /= ' ' ) then
      return
    end if
  end do

  do i = lenc + 1, len2
    if ( s2(i:i) /= ' ' ) then
      return
    end if
  end do

  s_eqi = .true.

  return
end
subroutine s_to_i4 ( s, ival, ierror, last )

!*****************************************************************************80
!
!! s_to_i4() reads an I4 from a string.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    28 August 1999
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, character ( len = * ) S, a string to be examined.
!
!    Output, integer IVAL, the integer value read from the string.
!    If blank, then IVAL will be returned 0.
!
!    Output, integer IERROR, an error flag.
!    0, no error.
!    1, an error occurred.
!
!    Output, integer LAST, the last character that was
!    part of the representation of IVAL.
!
  implicit none

  character c
  integer i
  integer ierror
  integer isgn
  integer istate
  integer ival
  integer last
  integer lens
  character ( len = * ) s

  ierror = 0
  istate = 0

  isgn = 1
  ival = 0

  lens = len ( s )

  i = 0

  do

    i = i + 1

    c = s(i:i)

    if ( istate == 0 ) then

      if ( c == ' ' ) then

      else if ( c == '-' ) then
        istate = 1
        isgn = -1
      else if ( c == '+' ) then
        istate = 1
        isgn = + 1
      else if ( lle ( '0', c ) .and. lle ( c, '9' ) ) then
        istate = 2
        ival = ichar ( c ) - ichar ( '0' )
      else
        ierror = 1
        exit
      end if

    else if ( istate == 1 ) then

      if ( c == ' ' ) then

      else if ( lle ( '0', c ) .and. lle ( c, '9' ) ) then
        istate = 2
        ival = ichar ( c ) - ichar ( '0' )
      else
        ierror = 1
        exit
      end if

    else if ( istate == 2 ) then

      if ( lle ( '0', c ) .and. lle ( c, '9' ) ) then
        ival = 10 * ival + ichar ( c ) - ichar ( '0' )
      else
        istate = 3
      end if

    end if
!
!  Continue or exit?
!
    if ( istate == 3 ) then
      ival = isgn * ival
      last = i - 1
      exit
    else if ( lens <= i ) then
      if ( istate == 2 ) then
        ival = isgn * ival
        last = lens
      else
        ierror = 1
        last = 0
      end if
      exit
    end if

  end do

  return
end
subroutine word_next_rd ( line, word, done )

!*****************************************************************************80
!
!! word_next_rd() "reads" words from a string, one at a time.
!
!  Licensing:
!
!    This code is distributed under the MIT license. 
!
!  Modified:
!
!    27 June 2008
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, character ( len = * ) LINE, a string, presumably containing
!    words separated by spaces.
!
!    Output, character ( len = * ) WORD.
!    If DONE is FALSE,
!      WORD contains the "next" word read from LINE.
!    Else
!      WORD is blank.
!
!    Input/output, logical DONE.
!    On input, on the first call, or with a fresh value of LINE,
!      set DONE to TRUE.
!    Else
!      leave it at the output value of the previous call.
!    On output, if a new nonblank word was extracted from LINE
!      DONE is FALSE
!    ELSE
!      DONE is TRUE.
!    If DONE is TRUE, then you need to provide a new LINE of data.
!
!  Local Parameters:
!
!    NEXT is the next location in LINE that should be searched.
!
  implicit none

  logical done
  integer ilo
  integer lenl
  character ( len = * )  line
  integer, save :: next = 1
  character ( len = 1 ), parameter :: TAB = char(9)
  character ( len = * ) word

  lenl = len_trim ( line )

  if ( done ) then
    next = 1
    done = .false.
  end if
!
!  Beginning at index NEXT, search LINE for the next nonblank.
!
  ilo = next

  do
!
!  ...LINE(NEXT:LENL) is blank.  Return with WORD=' ', and DONE=TRUE.
!
    if ( lenl < ilo ) then
      word = ' '
      done = .true.
      next = lenl + 1
      return
    end if
!
!  ...If the current character is blank, skip to the next one.
!
    if ( line(ilo:ilo) /= ' ' .and. line(ilo:ilo) /= TAB ) then
      exit
    end if

    ilo = ilo + 1

  end do
!
!  To get here, ILO must be the index of the nonblank starting
!  character of the next word.
!
!  Now search for the LAST nonblank character.
!
  next = ilo + 1

  do

    if ( lenl < next ) then
      word = line(ilo:next-1)
      return
    end if

    if ( line(next:next) == ' ' .or. line(next:next) == TAB ) then
      exit
    end if

    next = next + 1

  end do

  word = line(ilo:next-1)

  return
end