Missing mushroom and object generation question

[Nate]

This is for version 3.1.2 I've got one unidentified mushroom on my object info list. I'm guessing this is the mushroom of turbulence and that it can never be found in the current version because of the "#" in front of a couple of the fields for that mushroom in obj.txt. I've unsuccessfully searched here and at the development site.

Also, I've noticed that Power and Balance DSM seems to appear in clusters. I'll get 2 or 3 Power DSM and 6 or 7 Balance DSM and then neither for a long, long time and then another bunch. Is this a known behavior of the RNG?

-Nate

[dhegler]

On a separate note about mushrooms.... Why do they appear so scarcely? I bet I could walk into any cave around here on a hillside and find dozens!

I have played Angband for upteen years (it seems) and a week ago was the first time I ever found BDSM. I have still never found PDSM, but this was the first game I played in 3.1.2.

[Marble Dice]

I believe you are correct; without at least one "A:" allocation line, the mushroom will never spawn. The mushroom's effect (SHROOM_TURB) is not implemented, and so the mushroom would serve no purpose even if you found one.

The appropriate action would have been to comment out the entire entry in object.txt, which will prevent it from appearing in the knowledge menu. I'm not sure why only two lines of the object definition were commented out.

You could say it is a known behavior of the RNG to go on lucky/unlucky streaks, but more specifically, it's just the nature of probability.

[Nate]

Rng

Thanks for the info Marble Dice. I hear you on the luck of the dice. Like coin flips. 10 heads in a row! the coin must be rigged!. How to tell if a series of coin flips is really from flipping a coin or just made up? The made up series won't have enough long runs of one type or the other. I did my Masters thesis on statistically testing for the presence of patterns in piles of sedimentary rocks and I found that there was randomness over short sections of rock types superimposed on a longer term nonrandom cycle. So a longer term periodic cycle of lots of shallow water rock types and then lots of deeper water rock types but within any given section of shallow or deep water rock types, there was no way to predict the order in which the rock types would be deposited. The DSM behavior reminded me of that. A longer term cycle of lots of DSM vs little DSM but within each part of the cycle (lots or little DSM) no way to predict which items will be generated. I know there is some kind of debate about whether RNGs are really random but I don't know anything about the details. Back to the dungeon!

[Sirridan]

IT's always bugged me, what is a mushroom of Turbulence supposed to do?

[Derakon]

Nothing; its effect hasn't been coded yet.

I suppose it could be speed + starvation. Or speed + confusion.

[Marble Dice]

I know there is some kind of debate about whether RNGs are really random but I don't know anything about the details. Back to the dungeon!

Almost everyone on this forum will tell you that the RNG is not random, but is in fact deterministic, and that:

1. The RNG is omnipotent
2. The RNG is malevolent
3. The RNG will kill you
4. If the RNG does not kill you, it is only so the RNG may prolong your suffering
5. If the RNG gives you something good, it is only so the RNG can take it away

[Zikke]

Almost everyone on this forum will tell you that the RNG is not random, but is in fact deterministic, and that:

1. The RNG is omnipotent
2. The RNG is malevolent
3. The RNG will kill you
4. If the RNG does not kill you, it is only so the RNG may prolong your suffering
5. If the RNG gives you something good, it is only so the RNG can take it away

The RNG can fry ants with a magnifying glass. At NIGHT.
The RNG can divide by zero.

(and other assorted Chuck Norris facts, too)

[Tiburon Silverflame]

What RNG is being used? Don't feel like digging through the code to find out.

[Derakon]

As I recall, it's a homebrew. Someone ran some tests comparing it to the Mersenne Twister years ago and found that it's of comparable randomness, though.

Ultimately, it's not that the RNG isn't random; it's that people love to anthropomorphize things and see patterns that aren't there.

[zaimoni]

What RNG is being used? Don't feel like digging through the code to find out.

It's a reimplementation of a fairly standard addition-shift RNG; no in-source documentation of where the coefficients are from, but as it's very easy to get these things wrong I assume there is a properly documented source "out there".

My testing suggests it's naked-eye random for events with probability greater than about 1/27. (Below that point, save-scumming enchant __ scrolls starts hitting excessively many long runs of non-occurrence: the empirical chance of a 1 in n event having a run of 3n failures ideally is about 5% for moderately large n. Hardly a major failing.)

[Tiburon Silverflame]

That sounds like it's a simple linear congruential generator. Those are seriously NOT random; they have major sub-cycles in them. Yes, they're god-awful if you pick the parameters wrong...but we're talking TOTAL cycle lengths of, like, 10 when you do that. 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.

[Pete Mack]

@Tiburon: so what's your point?
Poor pseudo-randomness matters a lot when all you have is an array of random numbers, but composed with some complex state machine (like Angband), cycles aren't likely to be obvious to the end user.
They sure aren't obvious to me; if they were, I'd win every game in very small number of turns...

[LostTemplar]

For such a complex thing like andband you do not need random numbers, any uniformly distributed numbers will be OK.

[ekolis]

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