>  I'm having a problem with my program.  When I draw this using turtle = 
>  graphics, it isn't plotting all of the pixels, even though they fall = 
>  inside the range of the tree (and they have coordinates within the SIZE = 
>  of the turtle window). 
>   
>  But I think I have an even more basic problem - if I try to run the = 
>  NBodyBrute.java program on my computer, the bodies don't move at all - = 
>  this is when I've made no changes to this program or Body.java.  And I'm = 
>  running into the same problem when I use my own NBody.java program - the = 
>  bodies don't move.  What could be going wrong?  Is there a bug in the = 
>  program that is provided? 
>   
>  ~Rachel 

The programs seem to work for me fine.  It's hard to diagnose your
problem without access to your computer.

One thing you could do is to zip up your entire working directory.
Make sure the directory has the minimum files necessary to reproduce
the problem.  (Include the .class files.)  Send me the zip file and I
can see whether your working directory works on my machine.

Another thing you can try is to see whether any Turtle animation
program still works.

You could also do some of this detective work on a computer in the
Friend center on your own.  Or you could even finish the assignment on
the Friend center computers all together.