gd is a derivative from the once famous satangd data plotting program
which ran on GSIs former MVS mainframe computer.
gd has been kept as much data- and command-compatible to the original as possible,
so you can recycle old data as well as command files without major changes.

Here's a list of remaining differences as well as some hints to port old data.

Output devices

   On satangd/MVS there was a fixed list of output devices.
   gd has no fixed list, it supports any existing X11 or 
   PostScript device (files and printers):

   ... / DEVICE(ps65gps)    a postscript printer queue
   ... / DEVICE(plot.ps)    a postscript file
   ... / DEVICE(biori6k:0)  an X11-screen (number 0) on host biori6k

   See section on printing for details.

Prompting the user ...

   ... for input is bad style and has been kept at a minimum.

Cursor Input

   See section on cursor input for details.

Input files

   The line length is unlimited (MVS: 256 characters).
   Note that datasets may not contain line numbers.
   You should UNNUM datasets on MVS before FTPing them to UNIX.
   Nested INBED:s are allowed.
   Some manual conversions that might be necessary:

   MVS                        UNIX

   H: -Y                      H: Y*-1
   A:                         not available
   A():                       not available
   R:                         not available
   PHI:                       not available
   H: X,BIN(4)                not available
   H: PHI R                   not available
   P: CUT(cut1) CUT(cut2)     P: CUT(cut1,cut2)


Commands GMEMBER,GREAD

   GMEMBER is identical to command GREAD.
   There's no prompting for the file name.

GDISP vs GPLOT

   There is no difference between commands GDISP, GPLOT.
   Both commands can address any supported output device.

What happened to DCOPY ?

   Has been replaced by command GCOPY.

What happened to DDEVICE/FREE ?

   Use GDCLOSE or GPCLOSE instead.

Scaling / picture sizes

   The SCALING parameter is taken seriously: x-axis = scaling * 20 cm.
   If the printer you select is not capable of supporting large pictures
   it will cut them without warning.
   Use the SIZE parameter or the GCOPY/SIZE command to scale down the picture size.

Placing legends

   In contrast to the old satangd where the legends were placed
   automatically (but never in the right place) there is a new command GDESCR
   as well a new line tag GDESCR: in the input file which place legends at your desire.

2-dimensional data

   Contour- and cluster plots are available, isometric plots are not yet
   supported. A new cluster plot mode (full clusters) is available.
   A new display parameter NCUT allows to specify the number of cuts.
   However, labelled cuts are no longer supported. Use command GDESCR instead.

   See section on 2-dimensional data for details.

Fitting

   There are some enhancements for user functions.
   See section on fitting for details.

Fitting

   Attributes and linewidth of graphic elements have to be specified
   as only two items separated by a comma.

   MVS                        UNIX

   E: ARLINE(...,l,0.1,r)     E: ARLINE(...,lr,0.1)


Not yet available :

   Polar diagrams, SHIFT(), isometric/3D plots, analyzers, command GELEMENT