For the bit tweakers

[kiroje]

Just saw this and wanted to share it, nice bit of history and trick in getting the inverse aquareroot

code
http://www.codemaestro.com/reviews/9

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

[Dann Corbit]

http://www.jjj.de/fxt/fxtpage.html#fxtbook
Look at "Algorithms for Programmers"

[Steelman]

http://www.jjj.de/fxt/fxtpage.html#fxtbook
Look at "Algorithms for Programmers"

No application for chess engines?

[Dann Corbit]

http://www.jjj.de/fxt/fxtpage.html#fxtbook
Look at "Algorithms for Programmers"

No application for chess engines?

Are you kidding? It's crammed with stuff that will be useful for chess programs.

There are loads of bit twiddling algorithms, there are debruijn algorithm explanations and demonstrations.

Much of it is aimed at extended precision calculations, but there is plenty of other interesting stuff in there.

[cms271828]

Interesting, but when would you use an inverse square root in a chess engine, I don't think I use them in mine.

[WinPooh]

Interesting, but when would you use an inverse square root in a chess engine, I don't think I use them in mine.

But maybe proper use of an inverse square root is the main secret of Rybka's strength?

[Gerd Isenberg]

Interesting, but when would you use an inverse square root in a chess engine, I don't think I use them in mine.

But maybe proper use of an inverse square root is the main secret of Rybka's strength?

You mean the fast sigmoid bending of eval terms on the game phase via RSQRTPS?

[mcostalba]

Interesting, but when would you use an inverse square root in a chess engine, I don't think I use them in mine.

But maybe proper use of an inverse square root is the main secret of Rybka's strength?

You mean the fast sigmoid bending of eval terms on the game phase via RSQRTPS?

.

Nice to know this sigmoid implementation. I come up with a linearized one few weeks ago

http://64.68.157.89/forum/viewtopic.php?t=23860

But I didn't know this argument has been already investigated before.

[Dirt]

...inverse aquareroot..

Inverse square root is easy and usually just takes one or two instructions. Just multiply the number by itself.

This all seems to be about calculating a reciprocal square root.

[Dann Corbit]

Interesting, but when would you use an inverse square root in a chess engine, I don't think I use them in mine.

Distance to mate?
G,D,R