Comments on: Magical Square Root Implementation In Quake III

by: PNGout : Ramin Hossaini (blog)

Thu, 10 Apr 2008 22:45:05 +0000

[…] For those who don’t know, Ken Silverman is the programmer that created the game-engine for Duke Nukem 3D. Silverman received lots of praise from John Carmack - which says a lot because Carmack is co-founder of ID Software and lead developer for games like Doom and Quake (he also wrote what is likely the fastest inverse-square-root function, but that’s a topic for another day). […]

by: Those old C bit tricks | Oh Null!

Wed, 05 Mar 2008 01:34:26 +0000

[…] After spending a lot of years writing C code it is sometimes hard to get some of those “tricks” out of your mind. The thing I always felt about C was it seemed to encourage you figure out or use cool tricks. Couple that with graphics coding you can get some strange stuff like the infamous 0×5f3759df q_sqrt function. Even though some of them are fairly worthless in modern computing, they are fun to look at and think about why they work! […]

by: ATOzTOA

Tue, 05 Feb 2008 09:26:31 +0000

What the ???

Why can’t someone ask Carmack how he conjured the magic number :)

And why isn’t Newton’s Approximation used in common mathematics?

by: Cornell CS 322 - Intro to Scientific Computing » Blog Archive » Quake3’s fast invSqrt()

Wed, 30 Jan 2008 04:01:27 +0000

[…] CodeMaestro: Magical Square Root Implementation in Quake III […]

by: Graeme E. Smith

Fri, 23 Nov 2007 10:26:57 +0000

Is anyone aware of a double precision implementation? Presumably the magic number at the heart of the speed-up would need to be different.

by: Quest3D|Log » Blog Archive » Carmack’ magic constant

Thu, 22 Nov 2007 10:09:51 +0000

[…] Article link […]

by: Greg Dolley

Thu, 22 Nov 2007 04:37:40 +0000

Carmack didn’t invent this implementation. It’s an algorithm that has been around for about 20 years; Greg Walsh is suspected of inventing it. See the paper entitled, “Fast Inverse Square Root” by Chris Lomont for details. I think there’s a link to it on this blog; if not, you’ll find it on google for sure.

by: Primordial Ooze

Thu, 22 Nov 2007 02:26:11 +0000

links for 2007-11-22…

CodeMaestro » Magical Square Root Implementation In Quake III (tags: programming math) Mac Buyer’s Guide: Know When to Buy Your Mac, iPod or iPhone (tags: mac shopping)……

by: Mythor

Wed, 21 Nov 2007 13:09:53 +0000

The code is elegant but not written by Carmack.
Here is a short piece of the email

>Hi John,
>
>There’s a discussion on Beyond3D.com’s forums about who the author of
>the following is:

Not me, and I don’t think it is Michael. Terje Matheson perhaps?

John Carmack

And here you can find the rest of the search for the origin of this piece of code:

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

by: Daniel Mueller

Wed, 21 Nov 2007 10:01:10 +0000

And just to complete the References, here’s another excellent paper on the topic (probably more interesting than the one by Chris Lomont) http://www.mceniry.net/papers/Fast%20Inverse%20Square%20Root.pdf