[Edu-sig] teaching python using turtle module

[kirby urner]

I'm glad turtle graphics intersected my thinking re extended precision
decimals (Decimal type) on edu-sig just now.

I've updated my tmods.py to contain a turtle rendering the plane-net of a T-mod:

http://www.4dsolutions.net/ocn/python/tmod.py (runnable source)
http://www.flickr.com/photos/17157315@N00/4147429781/  (GUI view)

Here's the graphical output:

http://www.flickr.com/photos/17157315@N00/4148139184/in/photostream/
(Python 3.1)

If you actually wanna fold the T, you need to snip off the cap and
reverse it, per this diagram:

http://www.rwgrayprojects.com/synergetics/s09/figs/f86515.html

120 of them, 60 folded left, 60 folded right, all of volume 1/24, make
the volume 5 rhombic triacontahedron.

http://www.rwgrayprojects.com/synergetics/s09/figs/f86419.html

If you blow up the volume by 3/2, to 7.5, the radius becomes phi /
sqrt(2) -- what we're showing with Decimals.

The reason this seems unfamiliar is the unit of volume is the
tetrahedron formed by any four equi-radiused balls in inter-tangency.

I'm spinning this as Martian Math these days, yakking on
math-thinking-l about it, learned it from Bucky Fuller, Dave Koski et
al.

Kirby