explain xkcd - User contributions [en]

Talk:375: Pod Bay Doors

2025-03-23T22:03:31Z

172.70.58.45:

Made the "WHAT?" text italic, Because that's the way it is in the comic :3 [[Special:Contributions/121.54.48.38|121.54.48.38]] 01:34, 14 May 2013 (UTC)

Fantastic cartoon featuring two of my favourite characters... and with both the pod and the Discovery's hull being spherical they could even stand-in for 'cores'... quite literally "in spaaaaaace".[[User:Squirreltape|Squirreltape]] ([[User talk:Squirreltape|talk]]) 19:42, 14 February 2014 (UTC)

[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) said: OK, how is it possible that when I search YouTube AND Google, I don't get any direct matches for ' "daisy bell" "still alive" '? Where's our duet?
* HAL sings "Daisy" https://youtu.be/OuEN5TjYRCE
* GlaDDOS sings "Still Alive" https://youtu.be/Y6ljFaKRTrI
:{{unsigned|Iggynelix}}
**It is "GLaDOS for "Genetic Lifeform and Disk Operating System"

now i see that glados still runs on dos! [[User:An user who has no account yet|An user who has no account yet]] ([[User talk:An user who has no account yet|talk]]) 00:36, 7 September 2023 (UTC)

So, what is the small thing? I thought maybe it was an LED coming to replace the lightbulb. Is it something like that, or is it just a spaceship?? --Selah
:It's an EVA pod from the film, I believe. [[User:Booyahhayoob|Booyahhayoob]] ([[User talk:Booyahhayoob|talk]]) 00:06, 21 May 2015 (UTC)
*eats potatOS* YUM! {{unsigned ip|173.245.54.5}}

But wasn't GLaDOS technically female? {{unsigned ip|173.245.48.87}}

The song isn't "Daisy Bell", but, as Randall wrote, "Daisy Daisy" aka "A Bicycle Built for Two". This song dates, IIRC, from the late 19th or early 20th century.
[[Special:Contributions/108.162.241.123|108.162.241.123]] 22:00, 3 October 2016 (UTC)
:"Daisy Bell" appears to be the original title.[https://en.wikisource.org/wiki/Daisy_Bell] [[User:Fyndegil|Fyndegil]] ([[User talk:Fyndegil|talk]]) 19:23, 26 February 2021 (UTC)

Technically, GLaDOS becomes the deuteragonist in Portal 2. Check Please! [[User:StillNotOriginal|StillNotOriginal]] ([[User talk:StillNotOriginal|Talk to me!]]) 19:39, 18 May 2018 (UTC)

Yes, you are forced to cooperate with her after Wheatley knocks you both into Old Aperture. [[User:TheresAFlyAttackingMe|TheresAFlyAttackingMe]]

Amusingly, H.A.L. 9000 and GLaDOS do get to interact in the LEGO Dimensions level GLaD to See You - with GLaDOS being very much annoyed with H.A.L.'s presence and the references to "Dave".
https://lego-dimensions.fandom.com/wiki/H.A.L._9000
https://www.youtube.com/watch?v=o5zzndGoM3U

should there be a category about portal refs? - [[User:Bb777|this is a signature]] ([[User talk:Bb777|talk]]) 01:59, 22 March 2025 (UTC)
:What's a "portal ref"? --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 08:56, 22 March 2025 (UTC)
::portal refrence. sorry i suck at abbreviating. --[[User:Bb777|(((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((((]] ([[User talk:Bb777|talk]]) 00:13, 23 March 2025 (UTC)
:::aaand, What's a portal reference? Just a reference to portals? --[[User:FaviFake|FaviFake]] ([[User talk:FaviFake|talk]]) 07:05, 23 March 2025 (UTC)
::::I'm assuming that it's {{w|Portal (video game)}}, in context. That's some of what you get when you don't use capital letters. ;) (But I'm all down wit' da kids and groovy, man, so grok that hip lingo just swell, gee-willikers!) [[Special:Contributions/172.70.58.45|172.70.58.45]] 22:03, 23 March 2025 (UTC)

2043: Boathouses and Houseboats

2025-03-08T01:05:16Z

172.70.58.45: /* Trivia */ URL typo...

{{comic
| number = 2043
| date = September 7, 2018
| title = Boathouses and Houseboats
| image = boathouses_and_houseboats.png
| titletext = The <x> that is held by <y> is also a <y><x>, so if you go to a food truck, the stuff you buy is truck food. A phone that's in your car is a carphone, and a car equipped with a phone is a phonecar. When you play a mobile racing game, you're in your phonecar using your carphone to drive a different phonecar. I'm still not sure about bananaphones.
}}

==Explanation==
Most English {{w|English compound|compound nouns}} can be constructed recursively. In many cases they are written ''open'' or ''spaced'' like "piano player" (a player of a piano) or "player piano" (a piano {{w|Player piano|capable of unattended operation}}). But ''closed'' forms like "wallpaper" (paper for a wall) are not less common. Some other languages have many more compound words: The German word for "hospital" literally means "patient's house," and the Swedish word for "house trailer" literally means "house car".

[[Randall]] is engaging in creative linguistics again. This time he is humorously suggesting to use a consistent naming scheme for things holding other things, the same way we call a boat holding a house a houseboat. He is extending this to all combinations boats, houses and cars. This would, however, be somewhat impractical, as these names do not include why one thing is on an other, and are also sometimes ambiguous: a carcar can be a tow truck as much as a car carrier, and a househouse can be either an apartment (house in a house) or an apartment building (house containing houses).

Additionally, he is somewhat inconsistent in some parts of the chart. While the chart is supposed to show examples of neologistic compound words <x><y> that refer to a <y> that ''holds'' an <x>, rather than a <y> ''in'' an <x>. However, Randall's examples sometimes are those of the latter example. He proposes to call lifeboats, which are boats held by other boats, "boatboat", instead of using that to refer to boats holding other boats, such as floating drydocks. Additionally, it is established naval practice to refer to a boat which is carried by another vessel as a "ship's boat", and call any vessel that carries a boat a "ship". In other words, according to usual naval terminology, a "boatboat" is a contradiction in terms; it is either a "boatship", synonymous with ship and hence redundant, or a "shipboat", the ship's boat. "Apartment" is a similar case: an apartment is a house in a house, while a house that holds a house is an apartment building or apartment complex. (However, in the title text, Randall points out an <x><y> could also refer to a <y> in an <x>, similar to the lifeboat and apartment examples. Nevertheless, "lifeboat" and "apartment" do not fit with the rest of the items of the chart and disobey the rule annotated in the corner.)

In the title text: "Truck food" is in some areas a common term for the meals offered by "{{w|Food truck|food trucks}}." {{w|Car phone}}s were a feature in automobiles throughout the late 1960s, 1970s and 1980s, serving as the predecessors to mobile phones, although they were permanently installed into a car and not mobile. ''{{w|Bananaphone}}'', a song by Raffi Cavoukian, is also mentioned.

{| class="wikitable"
|-
! Real term
! Actual definition
! Randall's definition
! Inaccuracies in Randall's definition
! Randall's term
|-
| {{w|Tow truck}}
| A truck that pulls or carries cars
| A Car that holds a Car
| Definitions are flexible. Tow trucks and cars are both automobiles, but "car" usually means an automobile dedicated to passengers, while "truck" is intended for hauling cargo (in the tow truck's case, other automobiles). We must also distinguish whether "tow truck" simply refers to a truck (pickup or full-size) that is designed to only move one car (on a flatbed trailer or hooked up behind with a winch, letting either the front or rear wheels roll along the ground), or a semi-trailer equipped with a frame that permits the transport of several cars at once (a car carrier).
| Carcar
|-
| {{w|Garage (residential)|Garage}}
| A building for storing or repairing vehicles
| A House that holds a Car
| “Carhouse” actually does have Randall’s definition, but is far less popular than “garage.” It’s in the Oxford English Dictionary (using the spelling “car house”) and is used in To Kill a Mockingbird.
| Carhouse
|-
| {{w|Roll-on/roll-off|Car ferry}}
| A boat that carries cars, especially across a river
| A Boat that holds a Car
| Most car ferries hold more than one car at a time
| Carboat
|-
| {{w|Mobile home}}
| A home that can be moved by a truck
| A Car that holds a House
| The term "mobile home" refers to the home that is moved by a separate vehicle, not to the vehicle that moves it. (If the home is self-propelled, then it is called an RV (recreational vehicle).) The phrase "Trailer home" is also used.
| Housecar
|-
| {{w|Apartment}}
| A home within a building that has been divided into separate living units
| A House that holds a House
| The "apartment" is the individual home within the larger building, which is called an apartment building, possibly an apartment complex, but that usually refers to several apartment buildings on one property managed from the same office.
| Househouse
|-
| {{w|Houseboat}}
| A boat that is used as a house
| A Boat that holds a House
| A houseboat has a home that is part of the boat; it is not a separate home carried on a boat. However, a mobile home theoretically could be carried on a car ferry or a ship.
| Houseboat
|-
| {{w|Boat trailer}}
| A carrier that is towed behind a car or truck and holds a small boat
| A Car that holds a Boat
| The trailer is not the car; it is towed by the car.
| Boatcar
|-
| {{w|Boathouse}}
| A building for storing a boat
| A House that holds a Boat
| The word "house" typically refers to a residential building, but can refer to other buildings. The term more specifically refers to an enclosed, roofed dock where boats may be stored, protected from damage by the weather & other outdoor dangers.
| Boathouse
|-
| {{w|Lifeboat (shipboard)|Lifeboat}}
| A small boat carried on a ship, meant to be used to evacuate the larger ship, especially if it starts to sink or catches fire
| A Boat that holds a Boat
| By traditional nautical definition, a ship is a vessel capable of carrying a boat. Many civilian boats can carry simple watercraft such as inflatable rafts, canoes, kayaks or dinghies.
| Boatboat
|}

==Transcript==
:[A chart with three rows and three columns is shown, both with the same heading "car", "house", and "boat". On the top left a text with the word "this" two times embedded in a bubble and an arrow respectively pointing to the row and column heading reads:]
:A '''this''' that holds '''this'''

:[Most entries have the common word in black, but crossed out in red with another word below also in red. Two entries remain in green.]
:A Car that holds a Car: <s>Tow truck</s> Carcar
:A House that holds a Car: <s>Garage</s> Carhouse
:A Boat that holds a Car: <s>Car ferry</s> Carboat
:A Car that holds a House: <s>Mobile home</s> Housecar
:A House that holds a House: <s>Apartment</s> Househouse
:A Boat that holds a House: Houseboat (green text)
:A Car that holds a Boat: <s>Boat trailer</s> Boatcar
:A House that holds a Boat: Boathouse (green text)
:A Boat that holds a Boat: <s>Lifeboat</s> Boatboat

:[Caption below the frame:]
:I really like the words for "boathouse" and "houseboat" and think we should apply that scheme more consistently.

==Trivia==
The [https://www.explainxkcd.com/wiki/images/archive/3/38/20180907164439%21boathouses_and_houseboats.png original version of the comic] used a different wording to indicate which word held the other. The column word holds the row.

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Comics with red annotations]]
[[Category:Charts]]
[[Category:Language]]
[[Category:Confusion matrices]]
[[Category:Comics edited after their publication]]

Talk:3041: Unit Circle

2025-01-23T16:30:39Z

172.70.58.45: Funny quote lol

First [[Special:Contributions/162.158.175.72|162.158.175.72]] 23:00, 22 January 2025 (UTC)

This would actually be so helpful for my geometry class right now '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 23:06, 22 January 2025 (UTC)
:Are you saying you have problem with abstract thinking? Why should matter if the unit circle had radius 1 yard, 1 foot, 1 meter or 1 lightsecond? -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 23:12, 22 January 2025 (UTC)
::I don’t like having things defined as “x” and like to have exact measurements. The diagram just looks cleaner to me that way '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 23:38, 22 January 2025 (UTC)
:::There's nothing stopping you from considering non-dimensional lengths to be whatever unit you want. If you just write in, for example, "cm" after any linear dimensions, and corresponding units for areas and volumes, that's fine.[[Special:Contributions/162.158.158.169|162.158.158.169]] 14:24, 23 January 2025 (UTC)
::I prefer units of light-nanoseconds or the metric version parnsecs (don't think about it too hard :P) {{unsigned|SammyChips}} SammyChips 23:58, 22 January 2025 (UTC)
:::I like [[3038|square acrminutes per steradian]] '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 02:38, 23 January 2025 (UTC)
:::Please sign off with <code><nowiki>~~~~</nowiki></code>, or change your signature to include a link to either your talk page or user page. Thank you! '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 01:25, 23 January 2025 (UTC)
::::I did sign with <code><nowiki>~~~~</nowiki></code>, but the option for treating my signature as plain text was enabled. [[User:SammyChips|SammyChips]] ([[User talk:SammyChips|talk]]) 15:57, 23 January 2025 (UTC)
:::SammyChips, if that is supposed to be Parallax nano-seconds, you should understand that that is probably more like a Giga-Parsec. The parsec is the distance at which an object appears to move one second of arc when the Earth moves halfway around its orbit. (though I'm not sure which orientation.) [[User:Divad27182|Divad27182]] ([[User talk:Divad27182|talk]]) 03:34, 23 January 2025 (UTC)
::::I told you not to think too hard for that very reason :P It's actually parsec-nanosecond per year, but in a nod to the recent comics dealing with unit cancelation and making up personal scientific jargon, I collapsed it into its own unit. For those who didn't get it, a light-nanosecond is pretty close to a foot, and the "parnsec" is pretty close to a meter. SammyChips 15:50, 23 January 2025 (UTC)
::::: You Americans will use anything but the metric system![[Special:Contributions/172.70.58.45|172.70.58.45]] 16:30, 23 January 2025 (UTC)
:::My Millennium Falcon gets 14 parsecs to the Kessel Run, and that’s the way I likes it! [[Special:Contributions/172.68.186.34|172.68.186.34]] 06:26, 23 January 2025 (UTC)
:::I'm going to take all these desires for weird units with a barn-megaparsec of nackle. [[Special:Contributions/172.69.195.160|172.69.195.160]] 07:00, 23 January 2025 (UTC)
:yo Tori, [https://www.youtube.com/watch?v=VEJWE6cpqw0 ''this''] might help you with geometry too ;) [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 11:14, 23 January 2025 (UTC)
::I’ve watched that video before-it’s really cool and it’s one of my favorite videos ever '''[[User:42.book.addict|42.book.addict]][[User talk:42.book.addict|Talk to me!]]''' 16:10, 23 January 2025 (UTC)

Are "they" also searching for {{w|Doubling the cube|Apollo's doubled altar}}? [[User:Divad27182|Divad27182]] ([[User talk:Divad27182|talk]]) 03:22, 23 January 2025 (UTC)

I guess the correct wording is that $\pi$ is a trancendent number. Some irrational numbers e.g. $\sqrt{2}$ can be constructed by compass and ruler. {{unsigned ip|172.68.185.165|07:12, 23 January 2025}}
:To be more precise, constructable irrational numbers are those that can be obtained through taking square roots, even repeatedly. Transcendental numbers are out, but so are things like cube roots. Note also that the fact that there are no "absolute units" of length is a quirk of Euclidean geometry -- in, say, hyperbolic world, a unit circle like this could actually work. [[Special:Contributions/172.68.213.153|172.68.213.153]] 09:10, 23 January 2025 (UTC)
::Watch out you don't make that unit circle too big, or the square's vertices might stretch out to infinity and ignite the atmosphere! [[User:SammyChips|SammyChips]] ([[User talk:SammyChips|talk]]) 16:14, 23 January 2025 (UTC)

Didn't the unit kilogram lose some of it's mass? It may be working if something similar happened to this unit circle. [[Special:Contributions/172.69.214.117|172.69.214.117]] 15:43, 23 January 2025 (UTC)

Talk:3026: Linear Sort

2024-12-23T20:01:46Z

172.70.58.45:

First in linear time![[User:Mr. I|Mr. I]] ([[User talk:Mr. I|talk]]) 13:28, 18 December 2024 (UTC)

Due to the fact that O(nlog(n)) outgrows O(n), the Linear Sort is not actually linear. [[Special:Contributions/162.158.174.227|162.158.174.227]] 14:21, 18 December 2024 (UTC)
:If your sleep() function can handle negative arguments "correctly", then I guess it could work. [[Special:Contributions/162.158.91.91|162.158.91.91]] 16:27, 18 December 2024 (UTC)
::Yes, on a machine where sleep() allowed negative values (somewhat similarly but more limited than [https://esolangs.org/wiki/TwoDucks TwoDucks]), the algorithm would take linear time regardless of the used constant in place of 1e6. Also, with a smaller constant, the so-called linear optimization is not completely dissimilar to [https://en.wikipedia.org/wiki/Radix_sort Radix sort], which has time-complexity of O(mn), where m is the bitlength of the item, which becomes linear for any item of limited bitlength (such as int64_t). In school we were taught that this is effectively linear, but that is deceptive, since the actual sort time grows to log(n) by virtue of requiring longer memory per item to fit more items in such a list, because a radix sort of 16 bit integers would be limited to useful lists of up to 65536 unique values to sort, and you'd need to grow them to 32 bit integers. If the sleep constant was chosen precisely to match the worst case [https://en.wikipedia.org/wiki/Timosrt Timsort] would take - and I pick timsort because in addition to having O(n) best case, equal items won't be swapped or take time for such swaps - the time complexity deception would be identical to that of Radix sort: The algorithm would be linear, but only until you exceed e^(sleeping steps) unique items in the list (same as radix sort, although radix sort becomes unusable, and LinearSort() only becomes slower), and the time wasted is comparable as it in both cases bounded by a number proportional to the bitlength of the (longest) value, which is usually larger than log(n'), and never smaller, if n' are the number of distinct values. So, in some ways, 1e6 is corresponding to m in a radix sort. [[Special:Contributions/172.68.190.145|172.68.190.145]] 12:10, 23 December 2024 (UTC)
:It relies on 1 second being long enough to outcompete the maximum input length provided. The joke is that most sort operations that take an entire second or more are considered too slow to be worth doing. 02:30, 22 December 2024 (UTC)

That was fast... [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 15:35, 18 December 2024 (UTC)

Do I even want to know what Randall's thinking nowadays? [[User:Definitely Bill Cipher|⯅A dream demon⯅]] ([[User talk:Definitely Bill Cipher|talk]]) 16:02, 18 December 2024 (UTC)
:Does anyone every want to know what Randall is thinking nowadays? :P [[Special:Contributions/198.41.227.177|198.41.227.177]] 22:02, 19 December 2024 (UTC)

The title text would be more correct if Randall used e.g. Timsort instead of Mergesort. They both have the same worst-case complexity O(n*log(n)), but the former is linear if the list was already in order, so best-case complexity is O(n). Mergesort COULD also be implemented this way, but its standard version is never linear. [[User:Bebidek|Bebidek]] ([[User talk:Bebidek|talk]]) 16:35, 18 December 2024 (UTC)

According to my estimates extrapolated from timing the sorting of 10 million random numbers on my computer, the break-even point where the algorithm becomes worse than linear is beyond the expected heat death of the universe. I did neglect the question of where to store the input array. --[[Special:Contributions/162.158.154.35|162.158.154.35]] 16:37, 18 December 2024 (UTC)
:If the numbers being sorted are unique, each would need a fair number of bits to store. (Fair meaning that the time to do the comparison would be non-negligible.) If they aren't, you can just bucket-sort them in linear time. Since we're assuming absurdly large memory capacity. [[Special:Contributions/162.158.186.253|162.158.186.253]] 17:14, 18 December 2024 (UTC)

What system was the person writing the description using where Sleep(n) takes a parameter in whole seconds rather than the usual milliseconds? [[Special:Contributions/172.70.216.162|172.70.216.162]] 17:20, 18 December 2024 (UTC)
: First, I don't recognize the language, but sleep() takes seconds for python, C (et. al.), and no doubt many others. Second, the units don't have to be seconds, they just have to be whatever `TIME()` returns, and multiplicable by 1e6 to yield a "big enough" delay. Of course, no coefficient is big enough for this to actually be linear in theory for any size list, so who cares? To be truly accurate, sleep for `e^LENGTH(LIST)`, and it really won't much matter what the units are, as long as they're big enough for `SLEEP(e)` to exceed the difference in the time it takes to sort two items versus one item. Use a language-dependent coefficient as needed. [[User:Jlearman|Jlearman]] ([[User talk:Jlearman|talk]]) 18:02, 18 December 2024 (UTC)
: Usual where, is that the Windows API? The sleep function in the POSIX standard takes seconds. See https://man7.org/linux/man-pages/man3/sleep.3.html . [[Special:Contributions/162.158.62.194|162.158.62.194]] 18:57, 18 December 2024 (UTC)

If I had a nickel for every time I saw an O(n) sorting algorithm using "sleep"… But this one is actually different. The one I usually see feeds the to-be-sorted value into the sleep function, so it schedules "10" to be printed in 10 seconds, then schedules "3" to be printed in 3 seconds, etc., which would theoretically be linear time, if the sleep function was magic. [[User:Fabian42|Fabian42]] ([[User talk:Fabian42|talk]]) 17:25, 18 December 2024 (UTC)

This comic also critiques/points out the pitfalls of measuring time complexity using Big-O notation, such as an algorithm or solution that runs in linear time still being too slow for its intended use case. [[User:Sophon|Sophon]] ([[User talk:Sophon|talk]]) 17:46, 18 December 2024 (UTC)

Current text is incorrect, but I'm not sure how best to express the correction -- there do exist O(n) sorting algorithms, they're just not general-purpose, since they don't work with an arbitrary comparison function. See [https://en.wikipedia.org/wiki/Counting_sort counting sort]. [[Special:Contributions/172.69.134.151|172.69.134.151]] 18:25, 18 December 2024 (UTC)

Hi! I'm just gonna say this before everyone leaves and goes on their merry way. Significant comic numbers coming soon:
Comics 3100, 3200, 3300, etc, Comic 3094 (The total number of frames in 'time'), Comic 4000, Comic Whatever the next April fools day comic will be, and Comic 4096. Wait for it...[[User:DollarStoreBa'al|DollarStoreBa'al]] ([[User talk:DollarStoreBa'al|talk]]) 20:42, 18 December 2024 (UTC)
:Comic 3141.592654[[Special:Contributions/172.70.163.144|172.70.163.144]] 09:16, 19 December 2024 (UTC)

As everyone observed, the stated algorithm is not theoretically linear, but only practically linear (in that the time and space to detect O(n log n) exceeds reasonable (time, space) bounds for this universe). Munroe's solution is much deeper than that though - it trivially generalises to a _constant_ O(1) bound. [run a sort algorithm, wait 20 years, give the answer]. That's the preferred way of repaying loans, too. {{unsigned ip|172.69.195.27|21:46, 18 December 2024 (UTC)}}

Continues comic 3017's theme of worst-case optimization. [[Special:Contributions/172.70.207.115|172.70.207.115]] 00:32, 19 December 2024 (UTC)

It looks as though this function does not actually do the sort in Linear Time, it only returns in Linear Time.
The MERGESORT Function itself looks to only take one parameter and does not have an obvious return value indicating that it performs an in-place sort on the input mutable list.
This means that the list is sorted at the speed of the MERGESORT function, but flow control is only returned after Linear Time.
For a single threaded program calling this function there is no practical difference, but it would make a difference if some other thread was concurrently querying the list.
A clearer linear time sort might look like this:

function LinearSort(list):
StartTime=Time()
SortedList=MergeSort(list)
Sleep(1e6*length(list)-(Time()-StartTime))
return SortedList

Leon {{unsigned ip|172.70.162.70|17:31, 19 December 2024}}
:There's such a thing as pass-by-reference, variously implemented depending upon the actual programming language used. It's even possible to accept both ''list'' (non-reference, to force a return of ''sorted_list'') and ''listRef'' (returns nothing, or perhaps a result such as ''number_of_shuffles made''), for added usefulness, though of course that'd need even more pseudocode to describe. For the above/comic pseudocode, it's not so arbitrary that a programmer shouldn't know how to implement it in their instance.
:I might even set about to do something like use a SetStartTime() and CheckElapsedTime() funtion, if there's possible use; the former making a persistant (private variable) note of what =Time() it is, perhaps to an arbitrary record scoped to any parameterID it is supplied, and the latter returning the 'now' time minus the stored (default or explicitly IDed) moment of record. I could then have freely pseudocoded the extant outline in even briefer format, on the understanding what these two poke/peek functions are. Which is already left open to the imagination for MergeSort(). [[Special:Contributions/172.69.43.182|172.69.43.182]] 18:04, 19 December 2024 (UTC)

There are situations where you want to return in O(1) time or some other time that is not dependent on the input data to prevent side-channel data leaks. While the run-time of Randall's "O(n)" algorithm has an obvious dependencies on the input data, using the "Randall Algorithm" to obscure a different algorithm can reduce the side-channel opportunities. A more sure-fire way would be to have the algorithm return in precisely i seconds, where i is the number of seconds between now and the heat death of the universe. [[Special:Contributions/172.71.167.89|172.71.167.89]] 17:49, 19 December 2024 (UTC)

;Please write an explanation for non-programmers!
I don't understand this explainxkcd. The comic itself was less confusing. Can please someone who really gets this stuff write a section of the explanation that explains the joke to people like me who do not have a theoretical programming degree? I know that is a tall task but right now it reads as rambling and a bunch of 0(n) that makes no sense to me. I can cut and paste a bash script together and make it work. I can understand that putting a sleep for a million seconds in a loop somewhere makes it slow. But a layperson explanation of what makes a sort linear, what is linear, what is funny about that approach, would be better than all the arguing about 0(n) because we don't get it. Thanks in advance! You folks are awesome! [[Special:Contributions/172.71.147.210|172.71.147.210]] 20:51, 19 December 2024 (UTC)
:Maybe this would be a good start:
::--cut here--
::An algorithm is a step-by-step way of doing things.
::A sorting algorithm is a step-by-step way to sort things.
::There are several commonly used sorting algorithms. Some have very little "overhead" (think: set-up time or requiring lots of extra memory) or what I call "molassas" (yes, I just made that up) (think "taking a long time or lots of extra memory for each step") but they really bog down if you have a lot of things that need sorting. These are better if you have a small list of items to sort.

::Others have more "overhead" or "molasses" but don't bog down as much when you have a lot of things that need sorting. These are better if you have a lot of things to sort.

::A linear sorting algorithm would take twice as long to sort twice as many unsorted items. If it took 100 seconds to sort 100 items, then it would take 200 seconds to sort 200, 300 seconds to sort 300, and so on. Algorithms that take "twice as long to do twice as much" are said to run in "Order(n)" or "O(n)" time, where "n" is the number of items they are working on, or in the case of a sorting algorithm, the number of items to be sorted.

::For traditional sorting algorithms that don't use "parallel processing" (that is, they don't do more than one thing in any given moment), a linear sorting algorithm with very little "overhead" or "molasses" would be the "holy grail" of sorting algorithms. For example, a hypothetical linear sorting algorithm that took 1/1000th of a second to "set things up" (low "overhead") and an additional 1 second to sort 1,000,000 numbers (not much "molasses") would be able to sort 2,000,000 numbers in just over 2 seconds, 10,000,000 numbers in just over 10 seconds, and 3,600,000,000 numbers in a hair over an hour.

::The reality is that there is no such thing as a general-purpose linear sorting algorithm that has very little overhead (in both time and memory) and very little "molasses." All practical general-purpose sorting algorithms either use parallel processing, they have a lot of overhead (set-up time or uses lots of memory), a lot of "molasses" (takes a long time or uses lots of memory for EACH item in the list) or they are "slower than linear," which means they bog down when you give them a huge list of things to sort. For example, let's say the "mergesort" in Randall's algorithm doesn't have much "overhead" or "molasses" and it sorts 1,000,000 items in 1 second. It's time is "O(nlog(n))" which is a fancy way of saying if you double the number, you'll more than double the time. This means sorting 2,000,000 items will take more than 2 seconds, and sorting 4,000,000 items will take more than twice as long as it takes to sort 2,000,000. Eventually all of those "more than's" add up and things slow to a crawl.

::The joke is that Randall "pretends" to be the "holy grail" by being a linear sorting algorithm, but he has lots of "molasses" because his linear sorting algorithm takes 1 million seconds for each item in the list, compared to the 1,000,000 items per second in the hypothetical "linear sorting algorithm" I proposed.

::As others in the discussion point out, Randall's "algorithm" is "busted" (breaks, doesn't work, gives undefined results) if the mergesort (which is a very fast sort if you have a large list if items) is sorting a list so big that it takes over 1 million seconds per item to sort anyways. I'll spare you the math, but if the mergesort part of Randall's "algorithm" could do 1,000,000 numbers in 1 second with a 1/1000th of a second to "set things up," it would take a huge list to get it to "bust" Randall's "algorithm."
::--cut here--
:[[Special:Contributions/162.158.174.202|162.158.174.202]] 21:44, 19 December 2024 (UTC)

:Layman's guide to O(n) time, second try:
::--cut here--
::First, "O" is "Order of" as in "order of magnitude." It's far from exact.
::O(1) is "constant time" - the time it takes me to give you a bag that contains 5000 $1 bills doesn't depend on how many bills there are in the bag. It would take the same amount of time if the bag had only 500, 50, or even 5 bills in it.
::O(log(n)) is "logarithmic time" - the time is the time it takes me to write down how many bills are in the bag. If it's 5000, I have to write down 4 digits, if it's 500, 3, if it's 50, 2, if it's 5, only 1.
::O(n) is "linear time" - the time it takes me to count out each bill in the bag depends on how many bills there are. It takes a fixed amount of time to count each bill. If there's 5000 $1 bills it may take me 5000 seconds to count them. If there's 500 $1 bills, it will take me only 500 seconds.
::O(nlog(n)) is "linear times logarithmic time" - the time it takes me to sort a pre-filled bag of money by serial number using a good general-purpose sorting algorithm (most good general-purpose sorting algorithms are O(nlog(n)) time). If it takes me 2 seconds to sort two $1 bills, it will take me about 3 or 4 times 5000 seconds to sort 5000 $1 bills. The "3 or 4" is very approximate, the important thing is that "logarithm of n" (in this case, logarithm of 5000) is big enough to make a difference (by a factor of 3 or 4 in this case) but far less than "n" (in this case, 5000).
::O(n2) is "n squared" time, which is a special case of "polynomial time." "Polynomial time" includes things like O(n3) and O(n1,000,000). Many algorithms including many "naive" sorting algorithms are in this category. If I used a "naive" sorting algorithm to sort 5000 $1 bills by serial number, instead of it taking about 15,000-20,000 seconds, it would take about 5,000 times 5,000 seconds. I don't know about you, but I've got better things to do with 25,000,000 seconds than sort paper money.
::It gets worse (O(2n) anyone? No thanks!), but you wanted to keep it simple.
:[[Special:Contributions/198.41.227.177|198.41.227.177]] 23:30, 19 December 2024 (UTC)
::Personally, I've got better things to do than sort dollar bills, full stop.[[Special:Contributions/172.70.91.130|172.70.91.130]] 09:37, 20 December 2024 (UTC)
:: O() notations is about behavior with large values, not small values. Try the "handing a bag of bills" algorithm with a few million dollar bills. You're going to need a forklift. Getting a forklift is not, in practice, instantaneous. Big N notation is almost always a joke for people trying to solve real problems. It only works on an abstract machine with some really weird (not physically achievable) properties. [[Special:Contributions/162.158.155.141|162.158.155.141]] 20:54, 20 December 2024 (UTC)

Friendly reminder that some users of this site are just here to learn what the joke is, and not to read the entire Wikipedia article on Big O Notation. Perhaps the actual explanation could be moved up a bit, and some of the fiddly Big-O stuff could be moved down? I'd do it myself, but I'm not really sure which is which. [[Special:Contributions/172.70.176.28|172.70.176.28]] 06:42, 20 December 2024 (UTC)
:I mean, it is fairly fundamental to the joke, and therefore to the explanation. It might be possible to slim it down a bit, but I don't think you can explain the joke without ''some'' explanation of Big O.[[Special:Contributions/172.70.91.130|172.70.91.130]] 09:37, 20 December 2024 (UTC)

I've just come to the conclusion that I will never 100% understand 3026. [[User:Dogman15|Dogman15]] ([[User talk:Dogman15|talk]]) 10:14, 20 December 2024 (UTC)
:Tell me that again when you've actually tried the official process...
function Understand(comic):
StartTime=Time()
ReadExplanation(comic)
Sleep(1e12*length(comic)-(Time()-StartTime))
return
:[[Special:Contributions/172.70.162.56|172.70.162.56]] 11:10, 20 December 2024 (UTC)
::The article should start off "This is a joke about Big-O notation and sorting algorithms, a topic in introductory computer science education." then continue with something like "An algorithm is computer code for solving a general problem. Big-O notation is a method for describing the efficiency of algorithms." and maybe something like "Randall has designed an algorithm that appears more efficient than commonly considered possible, claiming to solve a popular challenge of many decades, by trying to game how the Big-O approach to analysis ignores the real speed of an algorithm, instead considering how it changes when the data is changed." [[Special:Contributions/172.68.54.209|172.68.54.209]] 02:43, 22 December 2024 (UTC)

Here's my crack at a shorter explanation of the joke, without explaining the entirety of the Big-O notation Wikipedia article and without getting unnecessarily pedantic. (Please keep this in mind when critiquing this explanation! I probably know whatever simplification you notice.)
:The joke here consists of two parts: (1) a linear-time sort of a list is mathematically impossible, and yet (2) a linear-time algorithm is presented, with it being roughly correct because Big-O notation hides the full picture on purpose. The title-text joke is that someone realizes (1) and investigates (2) because of the purposeful full-picture-hiding.
:Let's start with part (2): how Big-O notation is a bit handwavy and inexact. This is not to say it's not useful in computer science research and explaining differences between algorithms, but it inherently and on purpose hides the full picture. It's kind of like rounding away unnecessary digits when doing a back-of-the-envelope physics calculation, except in Big-O, the thing that is rounded is a mathematical formula. The formula is for calculating the time it takes for an algorithm to run (whether in (nano)seconds or something abstract like "number of operations"), and it will be in terms of ''n'', which is basically "how many things does your algorithm need to process" (in this case, it's the size of a list). An algorithm might be calculated to have a running time of something complicated like 32''n''2.796+1.31''n''+6500, but it's Big-O "rounding" would be expressed as O(''n''2.796). This is because as ''n'' grows larger and larger (into the billions), the extra stuff is irrelevant: except in special cases, an algorithm with a running time of O(''n'') will take less time than an algorithm taking O(''n''2) time, because no matter what the stuff you "rounded away" was, the former will eventually be less than the latter once ''n'' grows big enough.
:With the relevant bits of Big-O notation explained, we can look at the problem of sorting a list. This is a classic problem in computer science and it comes up in coursework all the time, so Randall assumes a lot of his audience will be familiar with it. Part (1) of the joke is that a linear, ''i.e.'' O(''n'') time, sorting of a list is mathematically impossible: just checking whether a list is sorted in the first place requires comparing every pair of elements at least once, taking O(''n'') time, and after this you have to swap elements that are out of place and check again. If you build an algorithm carefully you can get away with doing log(''n'') "scans" back and forth along the list, ending up doing log(''n'') scans of ''n'' time each, which comes to O(''n'' × log(''n'')) time. This "O(''n'' log ''n'')" time is accepted as the lowest general sorting algorithm average-case run-time, and all improvements to sorting algorithms are in improving the stuff that Big-O notation hides – remember how we rounded away all those factors as unnecessarily complicated and irrelevant? Turns out they're actually relevant in practice! They can be fine-tuned for real computers and practical inputs; the mergesort in the comic is special because it's guaranteed to always take the same time, no matter the input.
:Putting both parts together: the "linear sort" presented is "linear", taking O(''n'') time, not because it has actually magically found a way to cheat at math and do sorting faster than is possible, but because O(''n'') notation hides the fact that it just waits for a million (milli)seconds for each item in the list: O(''n'') looks faster than O(''n'' log ''n''), but what's actually going on is that 1,000,000''n'' is way slower than mergesort's O(''n'' log ''n'').
:Curiously, this is actually a thing that [[wikipedia:Galactic algorithm|does happen in computer science]], although not as blatantly as this: there are some problems for which there exists an algorithm with a "better" Big-O-notated time, but which for whatever technical reason run worse in practice on real computers than apparently-slower algorithms.
(And again, please remember that I've on purpose left out irrelevant technical details! I know about radix sort etc., and I know the difference between O, Θ and Ω, and I know about space complexity also; I do actually have a master's degree in this stuff and know what I'm talking about.) [[Special:Contributions/172.69.136.141|172.69.136.141]] 16:09, 23 December 2024 (UTC)
:Actually I already thought of an improvement to this explanation (if it were to be used as the main explanation): it's unnecessary to bring up Big-O notation in the first place, until explaining the title text. The comic itself just talks about linear time, and mergesort (and sorting in general) could just be explained as requiring "more than linear time" because of the repeated comparisons I already mentioned. (O(''n'' log ''n'') is "quasilinear" or "log-linear" time but introducing that term can – and in my opinion should – be avoided). The title text explanation requires explaining that "O(n) means linear", and a bit about how Big-O notation is "rounding" away the complicated parts of the formula. [[Special:Contributions/172.69.136.165|172.69.136.165]] 16:42, 23 December 2024 (UTC)

Why is the prose so terrible on this site? Who writes "As one can image in most contexts one would wish for...." and thinks other people can understand it? Please run your text through ChatGPT, it's free now. [[Special:Contributions/172.71.147.54|172.71.147.54]] 17:31, 23 December 2024 (UTC)

Regarding {{diff|360113|this edit}}, I have my reservations. While Log2 ''may'' be 'logical' in a system using binary, there's no reason why the algorithm cannot be implemented upon a trinary-based "machine code" system, or one in quad (and I actually have created a four-instruction 'ultra-RISC' microcode kernel, of sorts, that used base-4 principles, not base-2), or decimal/BCD, and then byte-size is commonly 8-bit with 16-bit, 32-bit and 64-bit extensions to the basic unit and ''could'' translate to an equivalent higher-base if you are bothered about ''n'' vs. log''x'' ''n'' efficiency at lower ''n''s and higher ''x''s. Could even be natural-log (for reasons entirely unrelated to the hardware/firmware/software it is implemented on, just what it needs to do). Most of the time, we don't care if it's O(log10 ''n'') or O(ln ''n'') or whatever, because the difference is an appropriate constant multiple. That's something generally not retained... we may have O(''m'' log ''n''), for independent variable ''m'', but something like O(2 log ''n'') is treated as O(log ''n'') equivalent, like O(2) is just O(1) in the final analysis, and why the O(1e8*n) reality sneaks through here as O(n). So, ''by actual implementation'', you can't actually say that O(''n'' log ''n'') will be gte O(''n'') always. With 1<''n''<log_base, it won't be. ...Whether or not we're free to consider either generality, though, I definitely won't ask you how algorithms actually stack up next to each other where run under ''n''=0 conditions! But at least O(''n''-1) isn't a common thing... ;) [[Special:Contributions/172.69.194.19|172.69.194.19]] 18:01, 23 December 2024 (UTC)
:What does this possibly have to do with explaining the comic? [[Special:Contributions/172.68.23.81|172.68.23.81]] 18:07, 23 December 2024 (UTC)
:Hi, I made this edit. I removed that bit because it's too pedantic for an ExplainXKCD explanation, and in my opinion completely unnecessary. We don't need to explain Big-O, we need to explain the comic. In addition, while the math is strictly speaking true in that x>x*loga(x) when x<a, in computer science literature and discussion base-2 logs are typically assumed to be the default; if it isn't, it needs to be marked as such. Additionally the whole point of Big-O is growth: sure, that inequality holds when x is small, but we're not interested in it being small. As for ternary or whatever, those never come up. A few ternary machines existed in the 60s, sure, whatever, and occasionally someone experiments with something weird, but of the billions of computers that are in use, all are binary. So basically my message is to remember what forum we're speaking in. [[Special:Contributions/172.69.136.141|172.69.136.141]] 18:43, 23 December 2024 (UTC)
::Interesting, and it probably can do without saying the bit that is removed, but not for the reason given in the removal. As pointed out, above, practical timing issues don't depend upon the base computer being binary or not ("assume log-base-2 because computers are all binary" isn't really a useful argument). Some theoretical function creating and using a basic binary tree might (according to its operational needs) scale its operational speed by log-base-2 as a key factor, but a version that uses a k-d tree by log-base-k (you can imagine them being ultiately functionally equivalent by way of a Cantor-pairing(/tripling/etc) equivalence, if you want justification for this hypothetical choice between). They'd both be considered O(... log N ...), give or take any other accompanyting factors (or overriding terms). But you can't say that an O(... log N ...) solution will take a-specific-base-of-N multiple of time, certainy not base-2. [[Special:Contributions/172.70.58.45|172.70.58.45]] 20:01, 23 December 2024 (UTC)

2891: Log Cabin

2024-11-24T13:19:25Z

172.70.58.45: Undo revision 357751 by 162.158.178.223 (talk) No such Category. (I can think of one possible other 'Floorplan', perhaps a third. Is there even demand for the category to be set up?)

{{comic
| number = 2891
| date = February 7, 2024
| title = Log Cabin
| image = log_cabin_2x.png
| imagesize = 353x265px
| noexpand = true
| titletext = I'm sure the building inspectors will approve my design once they finally manage to escape.
}}

==Explanation==
[[File:log_cabin_golden_spiral.png|thumb|301px|Golden spiral (approximately) overlaid on the floor plan]]

This is a comic featuring a {{w|floor plan}}, presumably of a {{w|log cabin}}, and a pun on the word "log". The odd part about it is the right half, which appears to be infinitely recursive copies of the building, a self-similar {{w|fractal}}. The house as a whole represents a {{w|golden rectangle}} with a side ratio of the {{w|golden ratio}} (Φ =(1+√5)/2 ≈ 1.6180339887...), with successively smaller living areas (further subdivided into rooms, to a common but shrunken and rotated plan) being square adjoined by a golden-rectangle of all smaller living areas in the manner of the areas defined by the classic {{w|Golden spiral}} diagram. The joke is that Randall is intentionally conflating the word "log" in the common phrase "log cabin," where "log" refers to the wood the cabin is made of, with a {{w|logarithmic spiral}}, as "log" is shorthand for "logarithmic".

Every square subunit of the premises consists of a main combined kitchen/lounge area, with an adjoining shower-equipped bathroom, and a hallway leading to a closet and two bedrooms (a double-bed one with en-suite bath-equipped bathroom, and another with a single bed; both having their own walk-in closet space). Between the kitchen and the dining table is the open doorway that serves as the entry into the next inwards level of the floorplan.

A visitor can also walk in a spiral by using the open doorways in the building plan.

In the title text, Randall says that he is confident that building inspectors will approve the design of his log cabin, assuming they can escape. As one moves deeper into the infinite spiral of architecture, the entire log cabin ''seems'' to be a denser labyrinth of rooms and hallways.

It is unknown how the inspectors lost in the inner rooms would shrink in the same ratio, and would only have to head out through the last doorway they walked in through (or two, if they're currently in the en-suite) and then exit each 'main' area in turn until they exited the building itself. If they have any trouble at all (other than rescaling themselves), it would be that there is ''always'' a further inward area that they might consider needs exploring to fulfil their inspection routine. This construction could imply folded spacetime. To perform a correct inspection, the inspectors might need sufficient relation that inner rooms are identical to the outer rooms, and to solve algebraic equations for various parameters.

It could have been that the repetition continued outside of what is drawn here, continuing to grow larger as it moves further out, except that only the top-level external entry has a door: the entries to each lower level only have open doorways marked with no door, and except for the clear marking of external windows on the first four iterations, with no internal ones (and therefore no equivalent windows on the subsequent iterations) precludes that possibility. In fact, the first iteration has windows on the 'southern' edge for the single bedroom and seating area, for which there are no equivalents on any of the other iterations.

[https://www.generations-quilt-patterns.com/log-cabin-quilt-block.html Log Cabin] is also a classic quilting block, which starts with a tiny square and spirals outwards.

==Transcript==
: [Plan view of a multiroom house or cabin, in the manner of an architectural drawing. The overall outline is a rectangle, with an aspect ratio of approximately 1:1.6. On the left side, five rooms — an open-plan kitchen/living/dining room, two bedrooms, and two bathrooms — form a perfect square taking up part of the overall rectangular outline. In the remaining rectangular part to the right, the top, square part is taken up by a copy of those five rooms, slightly smaller and rotated 90 degrees clockwise. In the bottom part of that part, the right-hand part is a second copy, smaller and rotated again. In the left-hand part, the bottom part is a third copy, smaller and rotated again. In the top part, the left-hand part is a fourth copy. And so on. It is clear that there is an infinite number of copies of the basic five-room plan, spiraling logarithmically inwards to infinity.]

:[Caption below the panel]:
: Log cabin

{{comic discussion}}

[[Category:Engineering]]
[[Category:Math]]
[[Category:Puns]]

Talk:3015: D&D Combinatorics

2024-11-24T13:17:46Z

172.70.58.45: /* The physical difficulties of an M-of-N locking system */

The bot originally created this page as “D Combinatorics”. I renamed it to the correct title and tried to get as many of the references as possible (including a few redirects). [[User:JBYoshi|JBYoshi]] ([[User talk:JBYoshi|talk]]) 00:54, 23 November 2024 (UTC)

:The title in the Atom feed (which I'm assuming the bot consumes) is "D Combinatorics". I'm guessing something in Randall's pipeline didn't like the ampersand. --[[Special:Contributions/162.158.154.160|162.158.154.160]] 01:41, 23 November 2024 (UTC)

::Yup, if you look at [https://xkcd.com/3015/info.0.json 3015's JSON] you see that <code>title</code> and <code>safe_title</code> differ, and if you look at the HTML page source you'll see '''3''' different things: <code><title>xkcd: D Combinatorics</title></code>, <code><meta property="og:title" content="D&amp;D Combinatorics"></code>, and <code><div id="ctitle">D&D Combinatorics</div></code>! So probably what happened is Randall entered D&D but was supposed to enter D&amp;D, and the openGraph tags adder code, having to be HTML-aware, decoded & normalized D&D as HTML would, but the other parts of the pipeline just ate it for some reason.

:By raw combinatorics: 71 + 52 + 34 + 20 + 10 + 4 + 1 ways to get each of 16 - 22 respectively, for a total of 192, out of 4(6^3) = 864 total. 192/864 simplifies to exactly 2/9. I have no idea how Randall found this; if anyone has an idea, please let me know. [[User:Kaisheng21|Kaisheng21]] ([[User talk:Kaisheng21|talk]]) 01:33, 23 November 2024 (UTC)
::I used some simple python code to loop over every dice and confirm and it's 2/9 [[Special:Contributions/162.158.158.111|162.158.158.111]] 12:11, 23 November 2024 (UTC)

It seems like we edited the transcript at the same time. The odds of rolling 16 or higher in this situation seem to be 2/9? [[User:Darkmatterisntsquirrels|Darkmatterisntsquirrels]] ([[User talk:Darkmatterisntsquirrels|talk]]) 01:29, 23 November 2024 (UTC)

: There are 864 possible rolls (6 * 6 * 6 * 4). If you enumerate all of the rolls you will find that 192 are 16 or higher. 192/864 = 2/9, the value from the explanation. [[Special:Contributions/172.68.54.139|172.68.54.139]] 01:41, 23 November 2024 (UTC)

I added a table of outcomes to clarify how it works out to 2/9, anyone know how to make it pretty? -- Laurence Cheers

A much simpler approach: Roll two six sided dice and sum the result. You are successful if the result is 5 or 9. That happens 8 times out of 36. 8/36 = 2/9. (Or successful if the sum is 4 or 6, or 2 or 7, or 2,3,4 or 11, or several other combinations.) [[Special:Contributions/172.68.54.139|172.68.54.139]] 01:41, 23 November 2024 (UTC)
:Clever, but dice rolls in D&D involving summing all the dice, applying modifiers, if any, and then comparing to one or more threshold values. Your method makes it very difficult to apply modifiers. [[Special:Contributions/162.158.41.8|162.158.41.8]] 02:49, 23 November 2024 (UTC)
::I think you misunderstand the problem here. This is not skill, no modifiers apply, it's purely probability [[Special:Contributions/162.158.158.111|162.158.158.111]] 12:11, 23 November 2024 (UTC)

Minor quibble, arrows aren't fired (unless they're flaming or self-propelled, perhaps), they are shot. (Shotguns are fired of course.) [[Special:Contributions/162.158.41.73|162.158.41.73]] 02:52, 23 November 2024 (UTC)
:Arrows are "loosed", even more accurately. At least to avoid the confusion from how so many things may be shot, or ''a'' shot. (Many different nouns, from a physical measure of liquer/coffee/vaccine to a projectile, or an even abstract fundemental of chance; and, as verb, projectiles perhps may be shot, then so may their targets.) [[Special:Contributions/172.68.205.178|172.68.205.178]] 14:32, 23 November 2024 (UTC)

Rolling 22 or lower on percentile dice (or, equivalently, 79 or higher) is close enough, and easier to come up with. (Give or take whether 00 is treated as 100 or zero.) Or directly represent the action: roll a d10. If it's 1-5, you lose. If it's 6-10, roll again; if it's 1-5 you lose, 6-9 you win, 10 roll again. (Modify slightly if you want to distinguish the case of grabbing *two* cursed arrows.) [[User:Jordan Brown|Jordan Brown]] ([[User talk:Jordan Brown|talk]]) 03:26, 23 November 2024 (UTC)

== Alternative exact solution for getting this probability using dice ==

Roll: 1d8, 2d6, 1d4 succeed on 19 or higher.

== Alternative way to calculate the probability of drawing two non-cursed arrows ==

I couldn’t remember the formula for binomial coefficients (“n choose k”), but there’s an easy way to calculate that the probability of drawing no cursed arrows is 2/9 without that formula. You just need to multiply the probabilities that each of the arrows drawn is not cursed. Since only two arrows are drawn, you only have to multiply two numbers.

The probability that the first arrow is not cursed is 5/10 – there are 5 non-cursed arrows and 5 cursed arrows out of 10 total. After taking out one non-cursed arrow, there are 4 non-cursed arrows and 5 cursed arrows out of 9 total, so the probability that the second arrow is not cursed is 4/9. Multiplying the two probabilities, the probability of drawing two non-cursed arrows is (4*5)/(10*9) = 20/90 = 2/9.

I was considering writing this observation in the Explanation section of the page, but I’m not if it belongs there. This solution avoids using formulas from combinatorics, so it might not be connected enough to the comic.—[[User:Roryokane|Roryokane]] ([[User talk:Roryokane|talk]]) 06:02, 23 November 2024 (UTC)

== My simple-minded approach ==

• Roll d10 once for your first arrow: if 1 to 5, the arrow is cursed, otherwise not;

• Roll d10 again for your second arrow: same rules, but repeat until you have a different number from the first one (so d10 is in fact only a d9 this time)

• I won't calculate probabilities – these are your arrows, live with it ;-)
[[Special:Contributions/172.69.109.51|172.69.109.51]] 07:33, 23 November 2024 (UTC)
:That has the benefit (over 3d6+1d4) of telling you which arrow(s) (if either) was cursed. [[User:RegularSizedGuy|RegularSizedGuy]] ([[User talk:RegularSizedGuy|talk]]) 07:52, 23 November 2024 (UTC)
:If you don't like re-rolls, you can make d9 out of 2d3. Nine possibilities, so just assign one of them (perhaps by rolling them one at a time) to be the more significant digit. Don't have a d3 handy? Use d6 and modulo off the extra! (1=1, 2=2, 3=3, 4=1, 5=2, 6=3) [[Special:Contributions/172.68.150.91|172.68.150.91]] 05:59, 24 November 2024 (UTC)

== The physical difficulties of an M-of-N locking system ==
There seems to be doubt that a "N locks and M keys to unlock them" system could be easily accomplished. I think it could be trivial, with strategically interlocking locked-restraints. A chain formed of bike-locks can give a larger locked loop that can be unlocked by just unlocking any ''single'' one of the constituent locks, leaving the other locked loops to not matter (or you could also try the {{w|Borromean rings}} system, whereby it is again secure against itself, until just one ring is opened up to reveal that the rest now ''aren't even locked at all''...). With almost arbitrary ability to cross-link (or, if you will, repeated/alternating-reflected Borromean triplet connections), you can extend the requirements to more than one unlocking being required (by looping chain elements to mre than just the 'adjacent' loops, sideways onto a parallel meta-loop or up/down the chain, all you might do is allow some slack (could be sufficient to get a thing held directly closed by the taut loop-of-loops, but not enough if the passage of the loop through a hasp/sneck actually prevents the otherwise free movement of the final slide-to-unlock action to occur), but a second (or third, or fourth) unlocking can be required to open-end the whole metaloop of locks. At the top end, M=N solutions are also trivial (e.g. two keys, two locks popularly of safety deposit boxes or [[2677: Two Key System|other things]]). Which is not to say that a specific M-of-N puzzle (where 1<M<N) might not need a ''little'' bit of thought to actually design and implement, but there's no obvious reason why all such combinations shouldn't be nicely doable. [[Special:Contributions/172.69.79.165|172.69.79.165]] 14:56, 23 November 2024 (UTC)
:Can we first confirm that the M-of-N Encryption was what Randall was referencing in the first place? [[Special:Contributions/172.71.154.140|172.71.154.140]] 03:17, 24 November 2024 (UTC)
::No, first confirm that this is what the explanation treats as what Randall was referencing. As it was, "complicated lock mechanics" and/or "magic" were suggested as the only ways of doing this, when this (or what we thought this was) just needs a little thought and N bike-locks suitably entangled. [[Special:Contributions/172.70.58.45|172.70.58.45]] 13:17, 24 November 2024 (UTC)

==Polyhedral Dice==
"other polyhedral dice, with the number of faces denoted by dX (e.g., d10 is a 10-sided die, with numbers from 1 to 10 on it)." - the d10 may be a poor choice as exemplar here; Back in the last century, when I was playing D&D, d10 were typically (and uniquely) numbered 0-9, not 1-10. This may no longer be the case, and I may be showing my age, but if it is still the norm, the d8 or d20 might be a better choice of example. [[Special:Contributions/172.68.210.6|172.68.210.6]] 02:40, 24 November 2024 (UTC)

== You've all been nerd-sniped. ==

[[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 10:53, 24 November 2024 (UTC)

566: Matrix Revisited

2024-11-14T13:39:17Z

172.70.58.45: /* Explanation */ Correction and adjustments.

{{comic
| number = 566
| date = April 8, 2009
| title = Matrix Revisited
| image = matrix_revisited.png
| titletext = I actually remember being entertained by both the sequels while in the theater. They just don't hold up nearly as well in later comparison.
}}

==Explanation==
This comic was drawn in celebration of the ten-year anniversary of the movie ''{{w|The Matrix}}''. (Despite the claims of the first panel, the movie was actually released on 31 March 1999 in the US, although it was next released in Australia on 8 April 1999.)

[[Megan]] is shocked when she realizes it is already ten years ago that ''The Matrix'' came out. This is an effect Randall has used to [[:Category:Comics_to_make_one_feel_old|make you feel old]] several times (for instance he mentions The Matrix again two years later in [[891: Movie Ages]].)

In ''The Matrix'', almost all of humanity lives in a computer simulation. Many years ago, robots took over the real world (not the simulation), and placed humans into the simulation while their body heat generated power for the robots. A few people have escaped from the Matrix, and they are on a mission with others to free the human race from the robots. The title of the strip is a reference to the documentary on the filming of ''The Matrix'': ''{{w|The Matrix Revisited}}''.

In the first three rows of the comic we see three famous scenes from ''The Matrix'' parodied by Randall. The characters are {{w|Morpheus (The Matrix)|Morpheus}}, with sunglasses; {{w|Neo (The Matrix)|Neo}}, as [[Cueball]] in the first two scenes and with a black coat in the third scene; {{w|Trinity (The Matrix)|Trinity}}, as [[Hairbun]]; and a security guard in the third scene, as another Cueball-like guy.

In the first scene Morpheus tells Neo that one cannot explain what the Matrix is and that he must see it for himself to understand. Morpheus is very mysterious as he tempts Neo to take a look himself, which, in the movie, leads to the next scene. In this comic, however, Trinity makes Morpheus look foolish by clearly explaining the Matrix in a single, simple phrase, and then telling him that he must suck at explaining. (The actual quote from the movie is <q>no one can be told what the Matrix is</q>, which makes more sense: even after being rescued from the Matrix, Neo at first refuses to accept that his entire life has been a simulation, becoming highly distraught when confronted with that truth. Morpheus later mentions that for this reason, it is unusual to rescue people past a certain age.)

In the next scene Morpheus (ignoring Trinity's remark, or in a separate rerun of the interaction) has reached the part of the scene where he shows Neo two pills, one red and one blue, and tells Neo that he can either take the blue pill and return to the simulation (the Matrix), never to hear about the Matrix again, or he can take the red pill and leave the Matrix, and "see how deep the rabbit hole goes" (a reference to ''{{w|Alice in Wonderland}}''). In the movie, Neo takes the red pill. In the comic, however, he mixes the two pills then {{w|Insufflation_(medicine)|snorts}} the purple powder he has created as though it was an illegal drug such as cocaine, and apparently winds up in a bizarre upside down and inverted dimension, presumably caused by his 'Drug Trip'. Even Morpheus now has no idea where they are. Note that the inversion of both color and orientation could be intended to evoke the idea of capturing an image on film (i.e. a film negative), which is ''really'' the only place where Neo and Morpheus exist. It is possible that the combination of pills allowed Neo to break through another layer of the simulation. Alternatively, this could simply be Randall trying to explain that they are in an alternate dimension whilst still remaining within the constraints of stick figures on white and black backgrounds.

The third scene is at the point that Neo and Trinity must save Morpheus, who has been captured by {{w|Agent (The Matrix)|agents}} of the simulation. They obtain many guns and much ammunition, holstering and clipping a large amount of their stock beneath trenchcoats (the remainder in large canvas bags that they carry). We are shown the point at which Neo is stopped at a security checkpoint in a building in the Matrix. A {{w|Metal detector#Security screening|security arch}} has shown him to have metal on his person, typically indicative of having inadvertently taken keys through the gateway rather than sending them through the luggage scanner (which has not yet shown the bag contents). A security guard tells him to remove any metallic items (such as the keys) and place them in a container in order to walk again through the scanner, cleanly. In the movie, he opens his trenchcoat to revealing his myriad of weapons, surprising the previously unwary guard, and then (with the assistance of Trinity) proceeds to dispatch all of the outclassed and outgunned guards that are present or arrive in immediate response. In the comic, Neo also opens his trenchcoat, but the guard's response of "eww" implies that Neo may instead be {{w|Exhibitionism#Types of exposure|mostly naked underneath}} and the guard is disgusted by him flashing his genitals.

Back in the real world, after watching the movie, Cueball turns to his friends (Megan and another Cueball-like guy) and exclaims that he had forgotten how great the movie is. When his friend suggests that they put on the other two sequels, there is a beat panel where Megan and Cueball look at each other, then they beat up the offender off-panel.

The two sequels to ''The Matrix'' are widely regarded as inferior to the original, with some fans {{tvtropes|FanonDiscontinuity|pretending they don't exist}}. This is what happens when Megan and Cueball return, and Cueball repeats his statement about how good it was. Then Megan is saddened by the fact they never made any sequels and Cueball agrees, having tried hard (even violently) to forget those sequels. In the title text, however, Randall disagrees with the characters in the comics, remarking that he enjoyed the films when he watched them in the movie theater, but agrees that they are not as good as the original.

On {{w|IMDb}} the original movie was still in the top 20 on their [http://www.imdb.com/chart/top?tt0133093&ref_=tt_awd top 250 chart] in December 2023, with an average of [http://www.imdb.com/title/tt0133093/ 8.7] vs. only [http://www.imdb.com/title/tt0234215 7.2] and [http://www.imdb.com/title/tt0242653 6.7] to the sequels (though even those two scores are relatively high compared to other action titles).

==Transcript==
:[Megan stands below two pieces of text, in a panel that is without a frame.]
:Today was the ten-year anniversary of the release of ''The Matrix.''
:I sat down to watch it again.
:Megan: Holy fuck, ten years ago?

:[The next three panels of the first row and the next two rows spoofs three scenes from The Matrix.]

:[In scene 1 Morpheus with sunglasses and Trinity with hair bun are talking to Cueball-Neo. Morpheus has his hands together.]
:Morpheus: Unfortunately, no one can explain what the matrix is. You have to see it for yourself.

:[Trinity lifts her hand.]
:Trinity: Sure you can. It's a computer simulation in which you live, thinking it's reality.
:Neo: Oh.

:[Morpheus takes his hands down and turns around glaring at Trinity who has also taken her hand down.]
:Trinity: ...What?
:Trinity: Look, maybe you just suck at explaining.

:[In scene 2 Morpheus is talking to Neo while holding a red pill and a blue pill. To the far right is a part of a table.]
:Morpheus: ...Or you take the red pill, and I show you how deep the rabbit hole goes.

:[Neo takes both pills from Morpheus.]

:[Neo crushes both the red and blue pills on a table top.]
:''Crush''

:[Neo snorts the resulting purple powder through a pipe he holds up to his face (his nose).]
:''Snort''

:[Morpheus and Neo are shown upside down in a frame with inverted colors, i.e., black background with white lines.]
:Morpheus: Now look what you've done.
:Neo: Where ''are'' we?
:Morpheus: I have no idea.

:[In scene 3 Neo, wearing a long, black trench coat, at a metal detector, is accosted by the Cueball-like security guard.]
:Guard: Please remove any keys, metallic items, weapons—

:[Neo steps close to the guard and opens his trench coat towards the guard, who is facing the reader. The reader can't see what Neo has under his coat.]

:[Same scene as above, but side view: Neo, on the left, is opening his coat toward the guard, who is on the right and seems to be looking down. Nobody speaks.]

:[Same scene as above but the guard now looks up to Neos face and finally speaks:]
:Guard: Eww.

:[In the last row of the comic we see three characters that have obviously just finished watching The Matrix. Cueball is sitting on the floor nearest to the TV, Megan is sitting on the floor, farther from the TV and a Cueball-like friend is sitting on an armchair, farthest from the TV.]
:Cueball: I forgot how good that movie was.
:Friend: Wanna put on the other two?

:[Cueball, still sitting has turned to face Megan. They exchange looks without speaking.]

:[View of room, which is now empty, as is the chair. Sounds comes from off-screen to the right.]
:''Crash''
:''Wham''
:Friend (off-screen): Ow! Ow!

:[Cueball and Megan are back in the room, zoomed in so the TV is no longer visible, but the chair is and it remains empty. The friend is nowhere to be seen.]
:Cueball: I forgot how good that movie was.
:Megan: Too bad they never made any sequels.
:Cueball: True.

==Trivia==
*The 6th, 7th and 8th panels have been turned into an internet meme.{{Actual citation needed}}

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Comics with inverted brightness]]
[[Category:Comics featuring Megan]]
[[Category:Comics featuring Hairbun]]
[[Category:Comics featuring Cueball]]
[[Category:Multiple Cueballs]]
[[Category:The Matrix]]
[[Category:Comics to make one feel old]]

Talk:3011: Europa Clipper

2024-11-14T12:12:34Z

172.70.58.45:

I'm not brave enough to actually add an explanation myself, quite yet, but ... I guess this is a reference to the fact(?) that Europa looks a bit like a creme brulee', when viewed from space? https://science.nasa.gov/jupiter/moons/europa/ It does look tasty ... :) [[User:ModelD|ModelD]] ([[User talk:ModelD|talk]]) 12:53, 13 November 2024 (UTC)
:I suspect it's more due to the need to drill through a couple miles of ice to get to the ocean; much like breaking through the sugar crust on a creme broule! [[User:Seebert|Seebert]] ([[User talk:Seebert|talk]]) 13:16, 13 November 2024 (UTC)

Thank you to the people at 9AM Post things on another website to try and explain XKCD Comics. -Forgotten_Mail {{unsigned ip|172.69.33.177|13:30, 13 November 2024}}

The comically large spoon!!!!!!!!!! I love those. -[[User:Psychoticpotato|P?sych??otic?pot??at???o ]] ([[User talk:Psychoticpotato|talk]]) 16:38, 13 November 2024 (UTC)
: Don't be sucked in! Protect yourself! https://rathergood.com/2017/02/10/spoonguard/ [[Special:Contributions/141.101.99.105|141.101.99.105]] 10:57, 14 November 2024 (UTC)

I think the "Crème brûlée is from France, France is in Europe, the moon is called Europa" connection is a bit of a stretch...? [[User:Yorkshire Pudding|Yorkshire Pudding]] ([[User talk:Yorkshire Pudding|talk]]) 18:36, 13 November 2024 (UTC)
: Eh, it's the same etymology. --[[Special:Contributions/172.69.134.230|172.69.134.230]] 11:04, 14 November 2024 (UTC)
:: That the currency used in France is the euro is due to the continent that France is in. The issue of the continent and the moon coming from the same classical source (for different reasons) rather stretches the link between the dish (from the country, from the country, from the region/continent, from the region of Greece, ''possibly'' from the pantheon) and the moon (directly from the pantheon). I agree with the 'stretch' assessment. You can probably find easier and more plausible (but wrong) links worth alluding to than that, which relies upon several steps and a ''possible'' polysemic pair of original links. [[Special:Contributions/172.70.58.45|172.70.58.45]] 12:12, 14 November 2024 (UTC)

"only a spoonful" moment 💔 [[User:CalibansCreations|'''Caliban''']] ([[User talk:CalibansCreations|talk]]) 19:20, 13 November 2024 (UTC)

Someone should add a reference to XKCD's previous mention of a Planetary Protection Officer: https://what-if.xkcd.com/117/ [[Special:Contributions/162.158.42.221|162.158.42.221]] 00:09, 14 November 2024 (UTC)

JUICE mentioned!!! cracker ham cheese cracker ham cheese cracker [[User:N-eh|N-eh]] ([[User talk:N-eh|talk]]) 07:31, 14 November 2024 (UTC)

Talk:2082: Mercator Projection

2024-11-03T23:29:32Z

172.70.58.45:

The choice of characters in this comic is...interesting. I never got the impression that White Hat was gullible. [[User:GreatWyrmGold|GreatWyrmGold]] ([[User talk:GreatWyrmGold|talk]]) 21:27, 7 December 2018 (UTC)
:White Hat is just a fill in character as Cueball so he can both be one way or the opposite. Definitely not like Black Hat or Beret Guy. I have added an example of Cueball spreading misinformation in the explanation, and also here it is White Hat that is the victim, just to show that your statement is not generally valid for White Hat. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 12:35, 10 December 2018 (UTC)

I can convince people that all of Randal's maps are real? [[User:Linker|Linker]] ([[User talk:Linker|talk]]) 00:53, 8 December 2018 (UTC)

But wait, how does driving north reach Alaska? I thought it was an island near Hawaii to the southwest. More seriously, should we mention that the Mercator does have useful properties such as preserving angles or is that too much for explaining the comic? [[Special:Contributions/162.158.186.108|162.158.186.108]] 06:12, 8 December 2018 (UTC)

People putting a joke in the incomplete tag but completely ignoring the “Please mention here why this explanation isn't complete.” part is really annoying [[User:DrMeepster|DrMeepster]] ([[User talk:DrMeepster|talk]]) 07:38, 8 December 2018 (UTC)
:Good Dr. It is an autobot that fills in the first page of the explanation, and here it is always clearly incomplete. Others may later delete that it is a bot that has made the explanation, but not knowing if it is complete, but also now knowing if it is not. And then there is the large text stating do not delete too soon. So I agree that reasons should be given for old comics that are suddenly listed as incomplete, but that the newest comic is listed as incomplete is just basic info ;-) --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 18:29, 9 December 2018 (UTC)
::Why doesn’t the autobot explicitly say that it is incomplete by virtue of being a new comic? [[User:Saklad5|Saklad5]] ([[User talk:Saklad5|talk]]) 19:54, 9 December 2018 (UTC)

Perhaps it should elaborate on "ridiculous" i.e. Cueball claims that the Mercator projection changes the topology of land and water masses, not just their relative size and (oh it's a long time since I did maths, so I'll call it) squishiness. [[User:ColinHogben|ColinHogben]] ([[User talk:ColinHogben|talk]]) 10:19, 8 December 2018 (UTC)

Mercator map projection has the advantage that shortest line between two points on Earth (on globe) is straight line in this projection. --[[User:JakubNarebski|JakubNarebski]] ([[User talk:JakubNarebski|talk]]) 11:17, 8 December 2018 (UTC)
::I'm afraid you are mistaken. A straight line on Mercator translates to a {{w|rhumb line}}, not a {{w|great-circle distance|great circle}}. Rhumb lines are useful for navigation, more so than great circles if all you have is a compass, but they are not (necessarily) the shortest distance between two points. [[User:Jaalenja|Jaalenja]] ([[User talk:Jaalenja|talk]]) 08:17, 10 December 2018 (UTC)

The largest islands in Lake Ontario are either the western parts of the Thousand Islands or the southern-most part of the City of Toronto. Neither would be considered "in the middle" of the lake. While Lake Erie has some islands in the middle, like Middle Island, Lake Ontario does not have similar navigation targets/hazards. [[User:Nutster|Nutster]] ([[User talk:Nutster|talk]]) 17:11, 8 December 2018 (UTC)

Both the XKCD comic (in its caption) and the explanation (in its current form) misuse the word "fact." The point that Randall is trying to make is that you can convince people of '''lies''' or anyway '''mistaken ideas''' by referring to the Mercator projection. '''Facts''' are by definition correct. [[Special:Contributions/162.158.63.166|162.158.63.166]] 13:53, 9 December 2018 (UTC)
::Facts can also be anything ''presented'' as objectively real. Under that definition, this is proper usage. [[User:Saklad5|Saklad5]] ([[User talk:Saklad5|talk]]) 20:02, 9 December 2018 (UTC)
:: Falsehoods presented as fact are facts only in the mind of someone like Trump. For the rest of us, Canada as an island is not a fact. Does still count as a factoid though; they by definition may only look like facts, and may or may not be true. [[Special:Contributions/162.158.38.106|162.158.38.106]] 17:01, 15 April 2020 (UTC)

I wonder if it is possible to make a map projection stupid enough to support this at first glance. [[User:Saklad5|Saklad5]] ([[User talk:Saklad5|talk]]) 20:05, 9 December 2018 (UTC)
: You could probably do it with a janky Peirce quincuncial that's not centered on the North Pole. [[Special:Contributions/172.68.59.108|172.68.59.108]] 15:05, 10 December 2018 (UTC)

The trivia should be merged with the main explanation. The fact that a projection can't erase a border, such as the land border between the US and Canada, is an important part of the joke. -[[Special:Contributions/108.162.238.161|108.162.238.161]] 06:33, 10 December 2018 (UTC)
:Agree, Done --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 12:35, 10 December 2018 (UTC)

You're supposed to capitalize "Northwest" in "Pacific Northwest". [[Special:Contributions/108.162.246.34|108.162.246.34]] 20:36, 3 November 2024 (UTC)
:Depends. The "Pacific Northwest" may be a semi-informal region in its own right, but the "Pacific" region (which may not necessarily be "The Pacific Ocean") could be considered a larger, or maybe even completely different, semi-informal region which (less formally) can be said to have a northwest sub(sub-)part.
:Just like the town of {{w|Rushden}} could reasonably, if confusingly, be said to be "in the North Northamptonshire south". [[Special:Contributions/172.70.58.45|172.70.58.45]] 23:29, 3 November 2024 (UTC)