The number of tickets available is limited based on the size of our venue, and last year tickets were sold out before the conference. Don’t miss your chance to register!

So, head on over to www.cposc.org to register, and we’ll see you in October! :)

The kits I ordered from Adafruit arrived! Here’s the list:

• 2 x XBee Adapter Kit [v1.1]
• 2 x XBee Module – XB24-ACI-001
• USB TTL-232 cable – TTL-232R 3.3V
• Adafruit Motor/Stepper/Servo Shield for Arduino kit – v1.0

The XBee module that Adafruit sells is the chip antenna version. According to Parallax, “The wire antenna versions will provide 20-30% more distance than the chip antenna in the same environment.” Still, I should be able to get at least 300 feet out of it.

Up until a few weeks ago I was basically keeping a ‘Code’ directory in Dropbox and that was about it. Now I’m using git on each computer (i.e. notebook, desktop, etc.) and made a Github account (github.com/thinkhole).

Right now I have two public repositories:

• Arduino-DS1620 – a library to use a DS1620 temperature sensor with an Arduino
• Euler – a few Project Euler solutions in Ruby

The Arduino library has a decent amount of documentation, and should be quite usable. The Euler solutions are well… hey, they work. :)

Playing with the Arduino a bit again tonight. Here’s a snippet (source) to read the analog output from a Sharp GP2D12 analog distance sensor and convert it to centimeters:

Seems to work reasonably well.

Mix them together and what do you get? Me having a great time making little blocks fall from the sky:

The Chipmunk Ruby documentation is a bit lacking, but it follows the C interface closely enough that I’ve been able to pick it up without a problem so far.

Basically, I randomly seed a bunch of objects and then let them bounce their way through the sequence until they bottom out at 1, and then drop them. There’s a counter in the top left that shows how many are left.

Anyway, here’s the video with the obligatory iMovie stock music in the background:

The little monster blocks are a free icon set from Fast Icon. I’m a huge fan. :)

I was surprised that no one had heard of Ubuntu One even though quite a few people in the room were running Ubuntu 9.10.

I’m having a lot of fun with this. :)

There’s a second video showing similar problems as well.

Looks like this is not uncommon, and the procedure is to take it back to the Apple store and they’ll replace it. That’s cool, but still kind of a pain.

We take any whole number n greater than 0. If n is even, we halve it (n/2), else we do “triple plus one” and get 3n+1. The conjecture is that for all numbers this process converges to 1.

So you start with some seed number (n) and keep moving to the next number in the sequence by either dividing by two or multiplying by three and adding one. If you start with 1, you’d get 1, 4, 2, 1. If you start with 5, you’d get 5, 16, 8, 4, 2, 1. The reason these are also known as “hailstone sequences” is because the numbers rise and sink like ice in an thunderstorm cloud. Every number ever tested has always ended up falling to 1, but it’s never been mathematically proven that every number does the same.

Anyway, here’s some Ruby that, given a seed (n), will yield each number in the sequence and return the total length:

I added a few lines to write the output to a .csv file and then plotted it (n=27) using R:

That’s 112 data points going as high as 9232 before eventually dropping down to 1.