NAME

       gdl - GNU Data Language incremental compiler

SYNOPSIS

       gdl  [--help]  [-h] [--version] [-v] [-V] [[-]-quiet] [-q] [ -arg value ] [ -args ...  ] [
       -e statement ] [ -pref=/path/to/preferenceFile ] [ batch_file ...  ]

DESCRIPTION

       gdl is an incremental compiler for the GNU Data Language (GDL).  GDL  is  being  developed
       with  the  aim of providing an open-source drop-in replacement for ITTVIS Interactive Data
       Language (IDL). It is also partially compatible with Visual Numerics (VN) PV-WAVE. IDL and
       PV-WAVE  are  registered  trademarks  of ITTVIS and VN, respectively.  GDL and its library
       routines are designed as a tool for numerical data analysis  and  visualisation.   GDL  is
       dynamically  typed,  vectorized  and  has  object-oriented  programming capabilities.  The
       library  routines  handle  numerical  calculations,   data   visualisation,   signal/image
       processing,  file  input/output (incl. graphical and scientific data formats such as TIFF,
       PNG, netCDF, HDF etc) and interaction with host OS.

       Information on GDL/IDL/PV-WAVE syntax and library routines can be found in e.g.:

       - GDL documentation draft at: http://gnudatalanguage.sf.net/gdl.pdf

       - IDL manual on-line @ NASA.gov: http://idlastro.gsfc.nasa.gov/idl_html_help/home.html

       - ITTVIS (ittvis.com) and Visual Numerics (vni.com) websites

       - comp.lang.idl-pvwave newsgroup

       A vast part of GDL library routines is implemented using open-source  libraries  including
       GSL,  plPlot,  and  optionally: readline, FFTW, ImageMagick, netCDF, HDF4, HDF5, libproj4,
       UDUNITS-2, libps and others.

OPTIONS

       --help (or -h)
              Show summary of options

       --version (or -v, -V)
              Show version of program

       --quiet (or -quiet, -q)
              Suppress welcome messages

       -arg value
              Tells COMMAND_LINE_ARGS() to report the following argument (may be  specified  more
              than once)

       -args ...
              Tells COMMAND_LINE_ARGS() to report all following arguments

       -e statement
              Execute  given statement and exit (last occurance taken into account only, executed
              after startup file, may not be specified together with batch files)

       -pref=/path/to/PreferenceFile
              (only partially working  now)  setting  using  external  text  file  few  variables
              including default preferences (e.g. X11 Windows Size)

       The -demo, -em, -novm, -queue, -rt, -ulicense and -vm options
              are ignored for compatibility with IDL.

       A list of batch files to be executed before entering the interactive
              mode (but after executing a startup file, if specified) may be given when not using
              the -e option.

FILES

       $DATADIR/gnudatalanguage/lib/*.pro
              Library routines implemented in GDL. $DATADIR is specified during  compilation  and
              usually  translates  to  /usr/share,  /usr/local/share  or alike. GDL includes this
              directory in its search path unless GDL_PATH or IDL_PATH  env.  variables  are  set
              (see below).

       $HOME/.gdl/history
              A file used for storing the history of commands issued in the interactive mode

ENVIRONMENT

       The  following  environment  variables have special meaning to gdl.  The GDL_* variant, if
       defined, takes precedence over any corresponding IDL_* variant.

       GDL_PATH, IDL_PATH
              The GDL command (script) search path.

       GDL_STARTUP, IDL_STARTUP
              A file of commands to be executed on startup.

       GDL_TMPDIR, IDL_TMPDIR
              A directory in which temporary files may be created.

       HOME, SHELL
              Variables influencing shell invocations from within GDL (SPAWN procedure and the  $
              interpreter  command).   Value  of  HOME determines as well the location of the GDL
              history-file.

       PATH   Determines search path when spawning child processes using the SPAWN procedure with
              the /NOSHELL keyword set.

       PYTHONPATH
              Influences behaviour of PYTHON procedure and PYTHON() function (available if GDL is
              compiled with support for calling Python code)

       GDL_MPI
              A message to be sent out using MPI_Send before initialization  of  the  interpreter
              (available if GDL is compiled with support for MPI)

       DISPLAY, XENVIRONMENT
              Tell GDL how to connect to the X server

       PLPLOT_DRV_DIR
              Override the default location of PLplot dynamic drivers.

       LC_*   The  locale-related  settings  accessible  via  LOCALE_GET() (GDL always uses the C
              locale internally)

BUGS

       Please    report    bugs,     comments,     patches     or     feature     requests     at
       http://sf.net/projects/gnudatalanguage/

AUTHOR

       The  primary  author of GDL is Marc Schellens <m_schellens@users.sourceforge.net>.  A list
       of contributors is available in the AUTHORS file shipped with  GDL,  and  on  the  project
       website (see above).

       The   original   version   of   this   manual   page   was   written   by   Sergio  Gelato
       <Sergio.Gelato@astro.su.se>.  It is currently a part of the GDL package, and is maintained
       by the GDL Team.

SEE ALSO

       netcdf(3), hdf(1), gsl(3)