Fast Inverse Square Root

[shvarz]

http://www.math.purdue.edu/~clomont/Math/P...003/InvSqrt.pdf

most of this went over my head, but for those of you who are more mathematically/programming inclined this may be interesting

[Numsgil]

I'm actually very familiar with this.  However, in most modern computers with a math coprocessor, the square root operation is going to be alot faster than almost anything you can make yourself, including using a custom inverse version.

Or that's my experience anyway.  Primarily this sort of thing is important if you're building hardware.  Video cards use this I'm sure.