LIB 557 (22Dh) -- GraphWriter

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* Copyright (c) 2001-2007 by Albert Graef, Johannes Gutenberg University,
* Mainz, Germany.

* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2, or (at your option)
* any later version.

* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.

* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

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REVISION HISTORY: (see src/ChangeLog for details)

07 Jan 2007 - 3.0 - 49G+/50G compatibility

17 Feb 2002 - 2.1 - better help function

16 Feb 2002 - 2.0 - more bug fixes and improvements:

  - all known bugs in the editor (RCL, zoom, some other minor problems in the
    display routines) have been fixed, as well as the broken EDGE-> and
    REVGRAPH operations (bad value errors)

  - good new stuff(TM) in the editor: node and edge label display (thanks to
    Thomas Rast for insisting ;-), and simplified label entry (the node/edge
    inform boxes now recognize single label values, and also add a null tag if
    no tag is given)

  - overhauled the manual, added bookmarks

11 Feb 2002 - 1.2 - bug fixes (inform boxes)

8 Feb 2002 - 1.1 - bug fix in ADDNODE2, HIST/STO support in browser,
overhauled the DIJKSTRA example

7 Feb 2002 - 1.0 - first official release

DESCRIPTION: GraphWriter is an interactive application which allows you to
create and edit "graphs" -- those abstract mathematical structures consisting
of "nodes" and "edges" which pertain to many important applications such as
network design and optimisation, scheduling, routing and visualization.
GraphWriter makes this interesting area of mathematics come to life on your HP
49G/49G+/50G calculator. To my knowledge it is the first and only graph editor
available for *any* calculator.

The graph is displayed on the calculator's graphics screen (PICT), using a 2D
coordinate system which can be configured by the user. There are two main
entry points: GRW creates a new graph, while GRED edits the graph on stack
level 1. Graphs are represented in adjacency list form, may contain node and
edge labels (as tagged values), and may have multiple edges and loops. A
number of user-level operations for use in programming and on the command line
are also provided.

GraphWriter is distributed under the GPL, Debug4x-based sources can be found in
the src.zip file. Documentation in PDF format is in GRW.pdf. The manual is
still rather terse, but hopefully enough to get you started. Well, if you're a
seasoned 49G user, you probably know how to find your way without the
docs. ;-)

The present version should work with all calculators of the HP 49 series (49G,
49G+, 50G). To install, transfer the GRW.hp library file to your calc, move
the resulting variable to any port (e.g., using the filer), press ON+C to
reboot and you should be set.

An example implementation of Dijkstra's shortest path algorithm can be found
in the examples directory, along with a sample graph ready to be used with
that program. These are plain text files which you can transfer to your calc
in ASCII mode as usual.

Note that this is still BETA SOFTWARE, so MAKE SURE YOU BACK UP YOUR MEMORY
BEFORE USING THIS LIBRARY. Bug reports, code donations and all kinds of
comments and contributions are welcome, of course.

Future releases of this software will be made available from www.hpcalc.org
and the GraphWriter website:
http://www.musikwissenschaft.uni-mainz.de/~ag/hp49

Enjoy!

Dec 2006

Albert Graef
Dept. of Music-Informatics
Johannes Gutenberg University Mainz
Germany

Email: ag@muwiinfa.geschichte.uni-mainz.de, Dr.Graef@t-online.de
URL:   http://www.musikwissenschaft.uni-mainz.de/~ag