3068: Rock Identification

2025-03-26T22:34:21Z

104.23.187.72: changed a word to a different word

{{comic
| number = 3068
| date = March 26, 2025
| title = Rock Identification
| image = rock_identification_2x.png
| imagesize = 430x409px
| noexpand = true
| titletext = 'Is it worth anything?' 'I dunno, is the answer to that question worth another $5?'
}}

==Explanation==
{{incomplete|Created by a GEOLOGIC BOT THAT WILL DO IT FOR $4 - Please change this comment when editing this page. Do NOT delete this tag too soon.}}
It is somewhat hard to identify rocks without knowing where they're from, but Randall insinuates that this is just a lie geologists insinuate to obtain free money from curious people looking to identify rocks and assures that the best way to get rocks identified is to pay the geologist you ask.

This subverts the expected "correct" way to ask the question, which in these sorts of tips is often made by asking a slightly different question that gives a reason for the person who knows the information to become interested, rather than feel like they are being asked to do work for you. Examples of expected ways to get the information might be to ask premptively, "Can you tell me where this rock came from?". Or, to draw their attention by being intentionally wrong, i.e. "Why is this granite red?"

Alternate Explanation: garnets in mica schists actually grow in $5 bill environments. That was sufficient geologic context.

==Transcript==
[Cueball is holding a small spotted rock]
Cueball: Can you identify this rock I found?

Ponytail: Not without knowing '''where''' you found. It's difficult to identify minerals by sight without the geological context.

[Cueball is holding $5 bill under the same small spotted rock]

Cueball: Can you identify this rock I found wrapped in a $5 bill?

Ponytail: Sure! Looks like garnets in a mica schist.

{{incomplete transcript|Do NOT delete this tag too soon.}}
[Caption above the comic:]
:how to ask geologists to identify a rock
:[A two-paneled comic, one panel being labeled "wrong:" and the other being labeled "right:"]
:[The panel labeled "wrong:"]
:[Cueball holds out a rock to Ponytail]
:Cueball: Can you identify this rock that I found?
:Ponytail: Not without knowing where you found it. It's difficult to identify minerals by sight without the geologic context.

:[The panel labeled "right:"]
:[Cueball holds out a rock wrapped in a $5 bill to Ponytail]
:Cueball: Can you identify this rock that I found wrapped in a $5 bill?
:Ponytail: Sure! Looks like garnets in a mica schist.

{{comic discussion}}

Talk:3062: Off By One

2025-03-13T13:28:53Z

104.23.187.72:

But what about floats? [[User:GreyFox|GreyFox]] ([[User talk:GreyFox|talk]]) 20:01, 12 March 2025 (UTC)

Is this dithering? [[User:Hcs|Hcs]] ([[User talk:Hcs|talk]]) 21:19, 12 March 2025 (UTC)

: Could be. --[[User:PRR|PRR]] ([[User talk:PRR|talk]]) 22:19, 12 March 2025 (UTC)

But if it's adjusted both on store and on read, then there is a chance (of about 1 in 22) that the value after read will be exactly the same as the value before store. This does not eliminate pre-existing off-by-one errors, and in fact, introduces new ones if the adjustment on read is off by one from the adjustment on store, when there was no off-by-one error in the original code. And what's worse - with a single store-read cycle, the value can never be off by 40 to 50. It can be off by up to 10, or by between 80 to 100, in either direction. --[[User:NeatNit|NeatNit]] ([[User talk:NeatNit|talk]]) 22:42, 12 March 2025 (UTC)
:I was ''just'' adjusting the explanation to imply this sort of thing (without having read your comment, just yet). Given the assumption that n=n±(40+rand(11)) at every stage (I'm assuming 'inclusive', Snaxmcgee!), two steps of 'intentional adjustment' might result in: -100 (x1), -99 (x2), -98 (x3), -97 (x4), -96 (x5), -95 (x6), -94 (x7), -93 (x8), -92 (x9), -91 (x10), -90 (x11), -89..-80 (x10..x1), -10 (x2), -9 (x4), -8 (x6), -7 (x8), -6 (x10), -5 (x12), -4 (x14), -3 (x16), -2 (x18), -1 (x20), ±0 (x22), +1..+10 (x20..x2), +80..+90..+100 (x1..x11..x1).
:This gives a chance of being entirely correct as 22/484 (4.5454...%) and ''each'' off-by-one as ''very'' slightly less (though ±1, in total is almost twice as likely!).
:Adding further steps (skipping odd step-cummulations, at least at first, until you get to nine of them and everything entirely stops being discontinuous) just spreads out an increased number of highs right next to zero deflection... [[Special:Contributions/172.70.86.129|172.70.86.129]] 23:38, 12 March 2025 (UTC)

::Obligatory quote:
There are two hard things in computer science: cache invalidation, naming things, and off-by-one errors.
::See here for a full story of this quote: https://twitter.com/codinghorror/status/506010907021828096
::--[[Special:Contributions/162.158.129.64|162.158.129.64]] 08:28, 13 March 2025 (UTC)
:::And 3 hard things in distributed computing: 3. Delivering messages exactly one time, 2. Making sure things happen in the correct order, and 3. Delivering messages exactly one time [[User:Jamcdonald|Jamcdonald]] ([[User talk:Jamcdonald|talk]])
::::Presumably 1 is not losing data? --[[User:NeatNit|NeatNit]] ([[User talk:NeatNit|talk]]) 10:19, 13 March 2025 (UTC)

In the comic, Cueball clearly says the adjustment amounts is ‘’between’’ 40 and 50, yet this explanation says the adjustment is from 40 to 50, ironically making an off-by-1 error on both ends of the range. Neither integers 40 nor 50 are “between 40 and 50”. [[Special:Contributions/172.71.154.39|172.71.154.39]] 10:43, 13 March 2025 (UTC)
:English language is imprecise with its use of "between", but it's usually taken as inclusive. Most people, when asked, "Pick a number between 1 and 10," will assume that 1 and 10 are both valid choices. Even in computing, you have things like Excel's RANDBETWEEN function to generate random integers, which is inclusive.

It's easy to make an off-by-one error without using a computer at all. Ask a friend how many fenceposts are needed for a 100-foot fence if the rails are ten feet long. [[Special:Contributions/172.71.30.199|172.71.30.199]] 12:58, 13 March 2025 (UTC)

explain xkcd - User contributions [en]

3068: Rock Identification

Talk:3062: Off By One