Comment by ArbitraryLimits | Hacker News Reader

Top New Best Ask Show Jobs

Comment by ArbitraryLimits | Hacker News Reader

Parent Full thread

ArbitraryLimits·

Dijkstra's algorithm is close enough to the Bellman equation for programmers, I guess :)

Also I don't really think taking a Taylor series for the inverse square root should count as an "algorithm."

I think the reason the inverse square root function got so much coverage was because of the bithacking of the float format, and the apparent WTFyness of the code. Also didn't it use Newtons method, not a Taylor series expansion? My math at that level is stale.

> ... and the apparent WTFyness of the code.

That's what ID Software thought:

http://en.wikipedia.org/wiki/Fast_inverse_square_root#Overvi...

It did use Newton's method, and the cool part was that with a carefully-chosen initial value, you only had to run 1 iteration to get a reasonably good result.

You're right, it was Newton's method.

Reply on news.ycombinator.com