write_xyy_data Subroutine

subroutine write_xyy_data ( data_file_name, lda, nrow, ncol, x, ierror )
!
!*******************************************************************************
!
!! WRITE_XYY_DATA writes a table of data to a file, for plotting by GNUPLOT.
!
!
!  Discussion:
!
!    The first column of data is assumed to be the independent variable, X.
!    Separate plots are made of X versus all the other columns of data.
!
!  Modified:
!
!    21 February 2001
!
!  Author:
!
!    John Burkardt
!
!  Parameters:
!
!    Input, character ( len = * ) DATA_FILE_NAME, the name of the data file.
!
!    Input, integer LDA, the leading dimension of X.
!
!    Input, integer NROW, NCOL, the dimensions of X.
!
!    Input, real X(LDA,NCOL), the NROW by NCOL data to be written.
!
!    Output, integer IERROR, nonzero if an error occurred.
!
  implicit none
!
  integer lda
  integer ncol
!
  character ( len = * ) data_file_name
  integer file_unit
  integer i
  integer ierror
  integer ios
  integer nrow
  real x(lda,ncol)
!
  ierror = 0

  call get_unit ( file_unit )

  if ( file_unit == 0 ) then
    ierror = 1
    write ( *, '(a)' ) ' '
    write ( *, '(a)' ) 'WRITE_XYY_DATA - Fatal error!'
    write ( *, '(a)' ) '  Could not get a free FORTRAN unit.'
    return
  end if

  open ( unit = file_unit, file = data_file_name, status = 'replace', &
    iostat = ios )

  if ( ios /= 0 ) then
    ierror = 2
    write ( *, '(a)' ) ' '
    write ( *, '(a)' ) 'WRITE_XYY_DATA - Fatal error!'
    write ( *, '(a)' ) '  Could not open the output file.'
    return
  end if

  do i = 1, nrow
    write ( file_unit, * ) x(i,1:ncol)
  end do

  close ( unit = file_unit )

  write ( *, '(a)' ) ' '
  write ( *, '(a)' ) 'WRITE_XYY_DATA:'
  write ( *, '(a)' ) '  Wrote the GNUPLOT XYY data file "' // &
    trim ( data_file_name ) // '"'

  return
endsubroutine write_xyy_data