Comments on: Repeatable Random

By: jackson

jackson — Thu, 02 Feb 2012 17:25:41 +0000

Yes, those are definitely good uses of the class.

I haven’t performance tested it, but that’s a good idea for a followup article. Thanks for the tip.

By: Alexander

Alexander — Thu, 02 Feb 2012 09:55:12 +0000

Very interesting – this also allows for things like tool-assisted speedruns in games (assuming you store the seed serially or somesuch). It also allows for physics engines to be deterministic.

Have you done a test for performance vs. Math.random()?

By: skyboy

skyboy — Fri, 19 Nov 2010 10:05:11 +0000

I’ve ported it over to AS3: https://github.com/skyboy/AS3-Utilities/blob/master/skyboy/utils/Random.as

I haven’t done extensive testing (ie. checking that the repeating period is the same length), but it looks well enough, and includes a couple helper functions, one being a static function to get results without needing to create an instance yourself (though it will be different between runs).

By: Cory

Cory — Fri, 04 Dec 2009 03:09:32 +0000

Hey Jackson– I ported this to Javascript at http://www.mawhorter.net/web-development/another-look-at-repeatable-random

I found this post while doing research for my own (significantly less powerful) repeatable random generator that creates an even distribution, which is linked in that post.

By: Another look at Repeatable Random » Cory’s Cogitations

Another look at Repeatable Random » Cory’s Cogitations — Fri, 04 Dec 2009 02:59:22 +0000

[...] found this post from Jackson Dunstan about a repeatable random class written in AS3. In that post, he mentioned that it could easily [...]

By: jackson

jackson — Wed, 21 Oct 2009 16:21:29 +0000

Thank you all for the good points! Zevan: I’d be really interested to see your results if you ever do port the Mersenne Twister.

By: Subblue

Subblue — Wed, 21 Oct 2009 13:31:06 +0000

You might find this link interesting about pseudo random number generators: http://www.bobwheeler.com/statistics/Password/MarsagliaPost.txt

By: Zevan

Zevan — Wed, 21 Oct 2009 13:06:07 +0000

hmmm looks like the tags got stripped out of my post… here is an image of the recurrence relation:

http://upload.wikimedia.org/math/1/4/4/144550627858cb6d44ceb02ba9434317.png

By: Zevan

Zevan — Wed, 21 Oct 2009 13:05:01 +0000

Nice post... @Og2t this is a linear congruential generator which uses the recurrence relation: Xn+1 = (aXn + b) mod m I was messing with these awhile back but couldn't get decent values for a, b and m.... looks like your a, b and m values make for some pretty good noise (tried this with setPixel()). In the past I've opted for the Tauseworthe RNG (which can be used to draw seeded noise) and have been meaning to port an example of the Mersenne twister

By: Og2t

Og2t — Wed, 21 Oct 2009 10:10:33 +0000

Pretty interesting that * 9301 + 49297) % 233280, never heard of it before… wonder who came up with it and if it really proves seed/iteration dependent.