USING THIS CODE

All files contained herein are by Brian C. Young, for Scientific Computing, 
Spring 2004, Harvey Mudd College.

Files:

drop3body.m
plot3body.m
vectabs.m

drop3body.m
Syntax: [hit, t] = drop3body(x0, y0, prec, tmax)
This introduces the fourth body at the point (x0, y0) and allows it to fall
until it passes within prec of one of the three attracting bodies, reaches escape
velocity, or passes the time tmax.  It returns a two-element vector, the first 
element being the index of the collided body, or 8 if escape velocity is reached,
or 0 if tmax was passed; the second element is the time index at which a result
was reached.

plot3body.m
Syntax: fract = plot3body(xmin, xmax, ymin, ymax, xres, yres, prec, tmax)
This calls drop3body over a grid of points on the range (xmin - xmax), 
(ymin - ymax), at a resolution of xres by yres.  The prec and tmax values are 
passed into drop3body; see their use above.  The function returns the matrix of
values returned by drop3body, and plots those values as an image on the current
figure.

vectabs.m
Syntax: len = vectabs(x)
This is a helper function to compute the magnitude of a vector representing a 
coordinate set in R(n).