## Time To Say Goodbye

When I started this blog, I wasn’t sure how much time I would devote to blogging, so I took the free WordPress route. I’ve been incredibly busy over the last year and a half and the lack of posts reflects that situation. I’m now in a position to devote a small amount of time to blogging and I decided to take the leap into the 21st century and create a WordPress site at algorithmist.net (my business site).

Since I now have a blog at my site, I will no longer maintain this one. I will leave all the posts online since many of them have code samples from which readers may realize some benefit.

I will continue blogging about math and programming, just in a different place. I hope you enjoyed the content of this blog and will keep up with the new one.

thanks!

– jim armstrong

## haXe and fast inverse square root

Inverse square root is a common operation in vector normalization, something that happens a lot in 3D math, particularly in game engines. An incredibly clever algorithm was developed using so-called ‘magic numbers’ and implemented in C, making its production debut in Quake.

Essentially, the algorithm makes a very smart guess as to an initial starting point that can be used to drive a single iteration of Newton’s method for 1/sqrt(x). You can read more about it here,

http://betterexplained.com/articles/understanding-quakes-fast-inverse-square-root/

http://www.geometrictools.com/Documentation/FastInverseSqrt.pdf

http://www.lomont.org/Math/Papers/2003/InvSqrt.pdf

http://www.beyond3d.com/content/articles/8/

Some time ago, I gave this approach a try using ByteArray and was disappointed with the performance, although it was a fun exercise. Recently, Nicolas Cannasse implemented the algorithm with haXe optimizations and the performance is awesome. Great work Nicolas!

## Mathematical Algorithm Predicts Political Power

Hmmm … this sounds like an interesting application of game theory and AI, and I’d like to get a reprint of the article somewhere as I don’t subscribe to any current journals. Even so, what I really want is an algorithm to eliminate politicians and political process. Whether we vote for tweedledumb or tweedledumber next month, all we get is another political bozo to replace the current one.

Now, where’s the algorithm to resolve that equation imbalance? Please forgive the rant – next post will be back on topic of text along splines