Missing mushroom and object generation question

[buzzkill]

So the first time I attack the monster, I hit him for one damage... then I hit him for two... then I hit him for three... :P

I've a better idea... mechanical hands, real dice, and an optical scanner. No more getting screwed over by the RNG.

[zaimoni]

That sounds like it's a simple linear congruential generator.

It is not: there's way too many slots. There is also a linear congruential generator, but it's used only to initialize the main RNG and compact the town and flavors into a 4-byte seed.

Those are seriously NOT random; they have major sub-cycles in them. ... But even if the coefficients are set up to give properly total cycle length, these generators inherently produce

R(n+k) ~= R(n)

where k is the sub-cycle length.

That is...elegant. (I'm not specialized in this literature, but that's not something I've seen in 200+ reasonably technical-looking web pages.)

[Pete Mack]

I would be happy to rewrite the random number provider to use an optional secure random number generator, like /dev/random on *NIX or CryptGenRandom on Windows. But I would be shocked, shocked, if you could tell the difference vs even a bad RNG like a linear congruential generator. Angband runs as the composition of the RNG with a really complicated finite state machine. So long as it can't get stuck in a cycle (like the borg), the lack of "randomness"* of the random numbers is not likely to be an issue.

* I put "randomness" in quotes, because even a secure RNG isn't necessarily truly random. It's just very, very hard to second guess. For true randomness, you need an ergodic (physically random) source like rolling dice or shuffling cards. This is surprisingly hard to come across on a purely digital system. The references above are to (mostly) ergodic RNGs. They use things like disk drive latency, mouse movement, keyboard delays, and WIFI signal strength as entropy sources. For the tinfoil hat set, you can buy true hardware RNGs for $100-$200. I suspect this won't fly with the angband crowd...

edited for broken link, /dev/random reference, and completeness

[zaimoni]

I would be happy to rewrite the random number provider to use an optional secure random number generator, like /dev/random on *NIX or CryptGenRandom on Windows.

Goodbye, RNG state within savegame. Reintroducing the V2.7.9- (?) behavior of just being able to reload ad-nauseum and get potentially different results every time sounds like a large step backwards.

[nobody]

does it?

i guess it might induce people to 'loadscum' but is there any other reason this is bad?

[Pete Mack]

Ok, ok. So no true rngs. How about using even a week secure hash of a bad rng?

Like MD4(random.Next())
That is still repeatable, but is a lot more "random".

[Atarlost]

It may actually be an improvement for competitions since currently they're repeatable if you log keystrokes.

[Nick]

Changing the RNG is a solution looking for a problem, IMHO.

[Pete Mack]

Changing the RNG is a solution looking for a problem, IMHO.

Well, yes.

[buzzkill]

i guess it might induce people to 'loadscum' but is there any other reason this is bad?

That's reason enough. I'll also go with don't fix it if it's not broken. The RNG works just fine as far as I can tell. Sure weird things happen every once in a while, but that's just life. The way I figure it, the RNG generates dozens, if not hundreds of random numbers between each move you make. The chance of any particular failure or repetition on it's part being noticed by you is non-existent.

If you take the RNG and continue to make it more and more random, wouldn't it eventually evolve into a non-random state?

[nobody]

are you theorizing something can be so random it'd be ordered?

[Sirridan]

are you theorizing something can be so random it'd be ordered?

Well... if we make the RNG always pick a number between 1 and 1 inclusive, it will always be perfectly uniform...

[Nate]

The context in which I noticed these possible clusters of DSM was definitely not normal game play. I was doing an experiment in collecting all the artifacts and was down to Mediator and Bladeturner. I cloned Great Ice Wyrms until I got them. As you can imagine, this provided plenty of opportunity to observe object generation. Under "normal" conditions where you get what you get and take on Morgoth when you think you're ready, I don't imagine any potential RNG issues would have much impact.