This code is essentially XGraph release 11.4, with some modifications
which were made for use by the NCSA Relativity group.
These modifications were made by Paul Walker, and he should be
contacted at the below address if you have any problems/questions
regarding these features.

1.	Animation.  XGraph will now do a *very* crude animation of
	your data sets.  It occasionally has problems with refreshes
	and will consequently run your animation three of four times.
	Consider this an undocumented feature!  You can adjust the
	speed of the animation with the -dl option.  I find "2" works
	well on a sparc displaying on MacX, "5" on a sparc on its
	own display, and "10" on an SGI or RS6K on its own display.
	Remeber, this animation is not being advertised as anything
	other than very crude, so if you are looking for production
	quality video, turn elsewhere.  We find it useful as it will
	quickly generate animation which shows time evolution. 

2.	Differentation.  You can press the "Derivative" button to
	see the first and second derivatives of your data set.  The
	method is a standard centered difference.  You cannot display
	higher than second derivatives.  Animation, zooming, etc...
	work in each of the derivative windows.  Endpoints are found
	linearly interpolating inner values to ends, so pay them
	little heed!

3.	New Color Map.  We couldn't differentiate the colors once we
	got past yellow, so we created a new color map.  If you don't
	like it, look in init.c for the variable "defColors" and 
	comment out the new one, replacing it with the commented
	old one.  Of course, you are free to insert your own choices
	here also ... Just use standard X color names. 


These modifications were made by Paul Walker, and distributed with the
Original author's consent.  See Copyright.h for information about
distribution and ownership of these changes.  Contact Paul Walker at

Paul Walker
NCSA
605 E. Springfield Ave
Champaign IL 61820
pwalker@ncsa.uiuc.edu

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1. Bug fixes -- there were a few.  Surface plotting works again.
   Added a bunch of assert statements to catch possible problems.
   Probably we could use more.

2. Can plot 1000 data sets rather than 112.  A bug fix was needed
   to make this happen.  An output message occurs every 25 sets so
   that you can see loading progress.

3. Improved naming: Long file names get truncated now.  Also, all
   data sets in file x will not simply be named "x".  They will now
   have the set number appended in parenthesis.

4. Compiles quietly on IRIX.  I haven't updated any other platform.

5. If you use the -m option and resize the screen, the old points
   are now cleared away.

Steve Brandt
brandt@aei-potsdam.mpg.de

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