Balmond's Sigma Code

The Search for the Sigma Code has a dense plot and relies on another imaginary narrator (not a monk this time, but) a boy called Enjil. If you have ever wondered why any prime number is greater than three will, when raised to the sixth power, leave a remainder of one when divided by nine, you will be at home with this book. -- Vanessa Thorpe, The Independent On Sunday - 13 September 1998

You get the sigma code of a given number n like this:
1. Calculate the sum s of all digits of n.
2. If s is smaller then 10, s is the sigma value.
3. Else set n=s and return to 1.
With this definition it is possible to calculate the sigma values of number sequences. The result of some simple sequences are beautiful patterns:

This diagrams you obtain from the Fibonacci and the Pell sequence by using (and modifing) the following script: SigmaCode.zip

Geodesic Shell

The structure of this shell is woven from isocurves and geodesic curves on a surface. Geodesic curves are also called plank lines, they can be build from straigth, but twisted planks. Mårten Nettelbladt studied them on his blog. Geodesic shells build in wood have been studied at the laboratory for timber construction of the EPFL.

Planks generated from lines on a surface with this script: TwistedBeams.zip


The (straight) bamboo strips of this chinese hat are following geodesic lines. Photo by drs2biz.

Strips & Rivets

A sculpture of the Boy Surface at Oberwolfach
Rivets generated from points on surface (grasshopper)
Strips generated from curves on surface (rhinoscript)

StripsAndRivets.zip