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DrawGraphics Figure-8 && CPU Strangeness

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  • Subject: [mg37451] DrawGraphics Figure-8 && CPU Strangeness
  • From: "Steven T. Hatton" <hattons at>
  • Date: Wed, 30 Oct 2002 00:51:04 -0500 (EST)
  • Organization: Global Symmetry
  • Sender: owner-wri-mathgroup at

In a sense this problem gives me an excuse to call attention to one of the 
best uses I've seen a computer put to.  The figure-8 Animation in David 
Park's DrawGraphics package is exactly the kind of graphical expression of 
the mathematics of physics which reviel more about the situation than pencile 
and paper lend themselves to. (People such as John A. Wheeler, and Hermann 
Weyl seem to have this kind of mechanism build into thier brains, and 
therefore don't need no stinkin' computer.)

This is on SuSE Linux 8.1, P4/w 1 GIG of RAM.

While I was exploring this animation I noticed something rather strange about 
the CPU's behavior.  If I open Help Browser -> Add-Ons -> DrawGraphics -> 
Examples -> Figure Eight Animation, the CPU utilization is virtually 0.

I evaluate the first cell to load the package and the CPU jumps for a second 
and then settles back down.  I then select the remainder of the notebook.  
The CPU utilization remains very low. Then I evaluate it.  The CPU 
utilization jumps way up, as is to be expected.  The animation frames are 
created, and the animation runs fine.  The CPU utilization remains very high.

The interesting observation comes when I stop the animation by quitting the 
local kernel.  If I select the cell holding the graphic, I notice the CPU 
utilization jups to 98%+-.  The kernel isn't even running at this time.  When 
I say I select the cell holding the graphic, I mean to say I select the brace 
to the right which has the 'foldable' indicator. Selecting the inner-most 
brace does not cause the CPU utilization to increase, but selecting any of 
its parents does.

Can someone explain this?

You can find the DrawGraphics package here:

Hatton's Law: 
"There is only One inviolable Law."

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