Since everyone else here was putting up banners, I created a banner for my blog. The text and figure come from Chapter 8 (The Deltoid) of EH Lockwood's A Book of Curves (1961). It was on sale for $1 at a book sale, so I snapped it up.
A deltoid is the concave triangular curve formed when a small circle rolls around the inside of a circle three times as big. Eric Weisstein's Mathworld has a nice animation as well as a description of its properties.
If you've ever played with Spirograph you might have drawn a deltoid. Under the fold is a spirograph applet (courtesy of Anu Garg) that lets you create this curve and other pretty ones:
More like this
As promised a little while ago, I've copied everything here and shut down the old blog. I've set up redirects so links to the old blog end up at the right place. Links to
A deltoid is the concave triangular curve formed when a small circle rolls around the inside of a circle th
This is my last post ever here. My blog has moved to http://scienceblogs.com/deltoid/ where I will join some fantastic bloggers at ScienceBlogs.
Check out Deltoid for a set of refutations of
I always assumed that deltoid was a reference to the awe-inspiring shoulders you developed from years of power-lifting.... Next you'll be telling be that my subscription to Penthouse is not for the real estate listings!
The interesting thing is how a simple process can produce spikes. The entire economics profession is based on everything being non-spiky. In other words variables like tax and consumption are linked by smooth curves with no abrupt changes.
It's good to see the deltoid again - although I misss the lime green.