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 occurrence 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)

       --fakerelease version
              setting   !VERSION.RELASE  to  that  value.  !VERSION.RELASE  is  often  tested  by
              procedures to decide whether  some  function  or  option  should  be  used.  It  is
              sometimes  possible  to use this option to fool a procedure that request a specific
              value of !VERSION.RELEASE

       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)

       GDL_GR_WIN_HEIGHT
              Sets the preference for the default height of a Windows(tm) graphic window

       GDL_GR_WIN_QSCREEN
              if  set  to  true  (1)  this  will  prevent  the  use  of the GDL_GR_WIN_HEIGHT and
              GDL_GR_WIN_WIDTH preferences and the default dimensions of graphic windows will  be
              1/4 of the screen dimensions

       GDL_GR_WIN_WIDTH
              Sets the preference for the default width of a Windows(tm) graphic window

       GDL_GR_X_HEIGHT
              Sets the preference for the default height of an X11 graphic window

       GDL_GR_X_QSCREEN
              if  set  to  true  (1)  this  will  prevent  the  use  of  the  GDL_GR_X_HEIGHT and
              GDL_GR_X_WIDTH preferences and the default dimensions of graphic  windows  will  be
              1/4 of the screen dimensions

       GDL_GR_X_WIDTH
              Sets the preference for the default width of an X11 graphic window

       GDL_WX_BACKEND
              can  be  set  to  [0,1,2] which will select, respectively, the backends 0,1 or 2 of
              plplot's old wxWidgets driver (plplot versions < 5.10). Backend 2 has  antialiasing
              enabled.

       GSHHS_DATA_DIR
              If  not  automatically  found, tells GDL where the gshhs files (coasts rivers, etc)
              are located.

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)