Graph-3D  v1.03
                         by Bert van Leeuwen, April 1993


QUICK SUMMARY: Graph-3D allows three dimensional display of parametric
equations in the form x=..., y=..., z=... It works in 640x480x16 mode
or (on some SVGA's) in 640x480x256 mode. It also supports shading from
a number of different viewpoints, as well as 6 different palettes. It
supports many different functions, including amongst other sin, cos, ln
and constants such as pi and e. The viewpoint of the graph can be selected
from a number of pre-programmed viewpoints or adjusted manually to
preference.

Files:
GRAPH3D.EXE     The executable file (requires about 161K of memory)
GRAPH3D.DOC     You guessed it! (This document in case you didn't)
SVGA256M.BGI    Svga driver
*.G3D           Saved graphs


Usage: The buttons and input boxes on the bottom of the screen can be clicked
on with the mouse or the following hot-keys on keyboard:

x, y, z    : Pops up the x, y and z equations for editing
t          : Minimum time
T          : Maximum time (shift-T)
p          : Number of points
o          : Options menu
s          : Start calculating & drawing graph
Q          : Quit (shift-Q)

The equations support the *,+,-,/ and ^ operators as well as brackets, the
variable t and several functions:

pi      : the value 3.141592654....
e       : the value 2.718281828....
sin()   : sine, argument must be in radians
cos()   : cosine
tan()   : tangent
arctan(): arctangent
cotan() : cotangent
arcsin(): arcsine
arcos() : arccosine
exp()   : exponential function
ln()    : logarithm base e
log()   : logarithm base 10
log2()  : logarithm base 2
abs()   : returns the absolute value
sqr()   : squares the argument
sqrt()  : square root

No error checking is performed to improve speed, thus if you make a typo, or
the equation parser doesn't understand what you wrote, your graph will just
assume value 0 for that particular equation, and you might not get the
desired results.

The options menu is fairly self-explanatory and obvious. The user defined
view point in the view options menu is controlled by the cursor keys. Some
fiddling with this option and you'll quickly understand how it works. As
soon as the desired viewpoint is achieved, just press enter.

This code probably has a few pesticide resistant bugs left, so if you have
any comments, suggestions, constructive critiscism etc. please contact
me at my internet address :  bert@rkw-lan.cs.up.ac.za

I will also probably add better SVGA support in the future (I'm not sure about
this though as the 16 colour mode looks pretty OK), try and find out what the
@#$#@%# is causing the mouse cursor to dissapear behind the menus and fix any
other bugs that I become aware of. I have also on occasion had trouble with
the ^ operator, but I can never seem to get the problem whilst debugging, so
maybe I dreamt it up.

Thanks to the following people for helping to realise this project:

Ron Loewy            : partial use of his mathematical parser
Jordan Hargraphix    : SVGA driver (Is Hargraphix a coincidental surname?)

and others for ideas, suggestions and bug reports.

Graph 3-D v1.03 by Bert van Leeuwen