Gravitational N-Body Simulation: 16 bit DOS version
June 1994
Written by Henley Quadling

This simple 16 bit Dos protected mode application allows you to simulate 
N particles which are subject to their gravitational interactions, by
clicking with a mouse cursor directly on the screen. Initial velocities
and different masses can also be entered. 

This program will use every iota of floating point power that your system has
to offer, try it out!

There is no limit on the number of particles; the speed of your fpu is the
only limiting factor. The calculation is a true three dimensional calculation,
with no cheating or anything unsavoury. There is an explicit accuracy control.

To learn how to use this program, type "nbody ?" (without the quotes), for 
the following message:

"Creating each particle requires two mouse clicks...

 Click the right mouse button twice for a default particle,
 which has unit mass and zero initial velocity.

 Otherwise, click once on the left button, and type a mass
 in (following the beep), and then click again on the left
 button to define the direction and relative magnitude of
 the initial velocity of the particle (represented by a
 red line).

 The actual magnitude of the particle mass or velocity
 depends on the values of the scaling factors.


 To stop the action during the simulation, click on
 the right button, and again to quit the program.
 Clicking on the left button during the simulation clears the screen.

 VGA/mouse/80387 are the minimum requirements..."

There is also a 32 bit DOS version of this 16 bit DOS program, 
which has SVGA support and is considerably faster. However, due to 
problems with the mouse cursor disappearing, I haven't uploaded it.
(If anyone has an idea about why this problem with the Borland Powerpack
for DOS occurs, I would like to hear about it.)

This DOS program is very crude. A decent (and very different) version 
of this program is available as an interactive multi-threaded 
win32 application (nbody*.zip) at the ftp.cica.indiana.edu 
(or mirror) site, in the win3/nt directory. The win32 version has 
many more features and is much easier to use than this crude 
DOS prototype.

I haven't made win16 or win32s versions. Future Windows NT and 
Windows 95 versions will make use of the more advanced graphics
capabilities, such as 3D openGL graphics.

Both this and the win32 program are free. This DOS program requires a 
mouse and VGA.

Any comments are welcome at my internet address:
HQUADLING@mnhep.hep.umn.edu

