explain xkcd - User contributions [en]

Talk:2256: Bad Map Projection: South America

2020-01-19T00:48:50Z

172.69.33.197: How do we know Finland is part of Eurasia? If Scandinavia was actually an island, separated from Europe by a strait running between the Baltic Sea and the Arctic Ocean, that was always covered by ice, would anyone have discovered it yet?~~~~

I overlaid this map on all the projections in https://www.explainxkcd.com/wiki/index.php/977:_Map_Projections to show the difference. Is that something this wiki wants? [[User:EmuSam|EmuSam]] ([[User talk:EmuSam|talk]]) 05:54, 17 January 2020 (UTC)
:I don't know about the rest of the wiki, but I certainly do! --[[User:T0]] ([[User talk:T0|talk]]) 10:40, 17 January 2020 (UTC)
:Heck yeah that's awesome! [[Special:Contributions/108.162.210.222|108.162.210.222]] 13:48, 17 January 2020 (UTC)
: I'm gonna venture out on a limb here in my toe-shoes and say that those of us reading the comments on the explain-XKCD wiki will geek our Azimov socks off over that. [[User:Iggynelix|Iggynelix]] ([[User talk:Iggynelix|talk]]) 13:59, 17 January 2020 (UTC)
: Huwah, want? I clicked the link above with high hopes :x How did you not upload it yet :D [[Special:Contributions/162.158.155.110|162.158.155.110]] 15:40, 17 January 2020 (UTC)
:yes, please! [[User:WhiteDragon|WhiteDragon]] ([[User talk:WhiteDragon|talk]]) 22:05, 17 January 2020 (UTC)
:What amuses me: Since you have the first comment, the wiki doesn't know how to show your picture on my iPad's Safari, so the bottom lines up with your comment and extends UP into the explanation, overlaid by the links for adding a comment etc. LOL! And I agree, totally fitting to include here. [[User:NiceGuy1|NiceGuy1]] ([[User talk:NiceGuy1|talk]]) 08:08, 18 January 2020 (UTC)
:I put the GIMP file here for anyone else to play with. https://drive.google.com/file/d/1QIJJNCaEICZ_8ozxpgRjTPjUECykWDjL/view?usp=sharing [[User:EmuSam|EmuSam]] ([[User talk:EmuSam|talk]]) 22:16, 18 January 2020 (UTC)

How many different kinds of transformation have been applied to South America? I can see resize, rotation, and skew (shear). Can't see any reflections or anything that looks obviously non linear. Anyone care enough to check? [[Special:Contributions/162.158.119.83|162.158.119.83]] 08:02, 17 January 2020 (UTC)
:Not an expert on the terminologies used, especially in English. Does what has been done to the south America that is where Australia should be qualify as resize? It is not maintaining the aspect ratios, and is much "shorter" in the direction that used to be north-south (the way chile is "long") (and is now east west) and much wider in the other one. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 08:17, 17 January 2020 (UTC)

My God. It's full of South Americas [[User:Cosumel|Cosumel]] ([[User talk:Cosumel|talk]]) 20:30, 18 January 2020 (UTC)

Note: 358 is country code for finland, which is completely missing in the projection. {{unsigned ip|162.158.238.216| 08:11, 17 January 2020}}
:Finland is part of Europe and Asia continent, which is now South America. It is thus not more missing thatn any country not in South America. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 13:43, 17 January 2020 (UTC)
::How do you know? If Scandinavia was actually an island, separated from Europe by a strait running between the Baltic Sea and the Arctic Ocean, that was always covered by ice, would anyone have discovered it yet?[[Special:Contributions/172.69.33.197|172.69.33.197]] 00:48, 19 January 2020 (UTC)
Something something a Brazilian South Americas how many is that [[User:Cellocgw|Cellocgw]] ([[User talk:Cellocgw|talk]]) 12:19, 17 January 2020 (UTC)

It's also similar to [[1653: United States Map]], isn't it? [[User:Nedlum|Nedlum]] ([[User talk:Nedlum|talk]]) 15:47, 17 January 2020 (UTC)
:No it is not similar but it is somewhat related. But there is all the states that are moved around, not one state that makes up all of USA. But take Collorado and make it small enough and you can build anything with that square state. :-) I think this one is closer related: [[1500: Upside-Down Map]]. But I have added both to the explanation for reference. --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 23:38, 17 January 2020 (UTC)

I wonder what projection the South America is pulled from. I also wonder whether that projection has the rest of the world laid out similar to this arraignment, or if they are the same projection used for layout as for the shape. [[Special:Contributions/162.158.146.176|162.158.146.176]] 17:39, 17 January 2020 (UTC)

Wait a minute. If Tierra del Fuego is replaced by the whole of South America, does this include a tiny Tierra? [[Special:Contributions/162.158.111.205|162.158.111.205]] 20:42, 17 January 2020 (UTC)
:Yes, there is clearly a small bend in the "tip" of the SA replacing Tierra. --[[User:Lupo|Lupo]] ([[User talk:Lupo|talk]]) 20:56, 17 January 2020 (UTC)
::So many layers :-) --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 23:38, 17 January 2020 (UTC)
:"{{w|The Last Battle|Further <s>up</s>''south'' and further in!}}" [[Special:Contributions/141.101.99.221|141.101.99.221]] 17:05, 18 January 2020 (UTC)

Reckon the twoislands west of sulawesi are actually representing the two separate countries that make up the island of New Guinea ... there are indonesian islands between sulawesi and irian jaya but they are relatively small. Plu irian jaya kind of looks like SA [[User:Boatster|Boatster]] ([[User talk:Boatster|talk]]) 21:30, 18 January 2020 (UTC)
:I used https://en.wikipedia.org/wiki/List_of_islands_by_area to make up the list. I think New Guinea is only one SA as all the others are a single SA to a single island or continent, including not separating Europe and Asia. [[User:EmuSam|EmuSam]] ([[User talk:EmuSam|talk]]) 22:16, 18 January 2020 (UTC)

Was South America chosen because its shape is the ur-geography, sort of a platonic land solid?

2255: Tattoo Ideas

2020-01-15T16:51:24Z

172.69.33.197: /* Transcript */ add categories

{{comic
| number = 2255
| date = January 15, 2020
| title = Tattoo Ideas
| image = tattoo_ideas.png
| titletext = The text ALL YOUR BASE ARE BELONG TO US with a lengthy footnote explaining that I got this tattoo in 2020 and not, as you may assume, 2001, but offering no further clarification.
}}

==Explanation==
{{incomplete|Created by a TATTOO CONTAINING ALL TATTOOS THAT DO NOT CONTAIN THEMSELVES. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
This comic is a list of potential tattoo ideas. Many of them play on the trope of regretting a tattoo by being tattoos of things that would not be useful outside of the immediate future, while others are simply ludicrous ideas with little functionality.

===Table of entries===
{|class="wikitable"
! Randall's text
! Explanation
|-
| Lorem Ipsum text
| {{w|Lorem ipsum}} is the beginning of and shorthand for a long section of shuffled-up Latin text. It is often used by both print and web designers as placeholder text until final content is available. Having a Lorem ipsum tattoo would possibly suggest that the tattoo's text is a placeholder for a "final" tattoo.
|-
| Email password
| Getting a tattoo of your password could compromise the security provided by your password. Additionally, it is recommended and, in some cases, required to update your password regularly; which would result in your tattoo either becoming out of date or updated (which is difficult)
|-
| Graph of the popularity of tattoos over time, with the date I got the tattoo marked (Update regularly)
| This would likely take the form of a {{w|run chart}}, showing the continual rise and fall of tattoo popularity over time. [[Randall]]'s love of charts and graphs is [[:Category:Charts|a regular theme]] in the strip. On the surface, getting a tattoo of a tattoo-themed chart would seem appealing. But a chart that tracks over time would become outdated within a few years, making it problematic for a (presumably permanent) tattoo. The solution to this appears to be a note to update the tattoo regularly, presumably as new data becomes available. This would require having the tattoo altered repeatedly, possibly every year; the artist would need to add on to the existing tattoo by extending the x-axis and the data. Depending on the scale of the x- and y- axes, as well as the position and orientation of the graph on Randall's body, this might actually be feasible for Randall's entire lifetime. However, it would involve additional pain, expense and time commitment. Maintaining this novelty tattoo for the rest of his life would seem excessive, but giving it up would once again mean he'd eventually be left with an outdated tattoo.
|-
| "CHANGEME"
| In programming, some text fields are initialized with "CHANGEME" to allow the programmer to get the program running for development purposes, while making it obvious that the actual text needs to be written and inserted. This would be a very difficult operation to perform with a tattoo.
|-
| Slide rule markings on forearms
| A {{w|slide rule}} is a set of logarithmic scales that are used to perform mathematical calculations. Having a set of slide rule markings on his forearms could be convenient, but if he grows, or gains or loses weight, the scales might become distorted.
|-
| EURion constellation, so no one can photocopy pictures of me
| The {{w|EURion constellation}} is a set of five circles in a roughly X-shaped pattern that is put onto lots of currencies. When this design is detected, many photocopiers will refuse to make a copy.
|-
| The sentence "It's what my tattoo says" written in another language
| Intended to provoke the question "What does your tattoo say?" from people not fluent in that language, thus resulting in an interesting / confused exchange.
|-
| Tissot's indicatrix
| {{w|Tissot's indicatrix}} is a matrix of circles placed on a map that change size and proportions (possibly turning into ellipses) based on map distortion. As a tattoo, that would be useful in tracking any distortion of the skin since you had the tattoo.
|-
| Summary of the [https://www.snopes.com/fact-check/suffer-to-be-beautiful Snopes page on the tattoo epidural thing] (Lower back)
| The "tattoo epidural thing" is a mostly debunked medical concern that anesthesiologists attending women in labor would refuse to administer spinal anesthetic by needle through skin with tattoo ink, out of fear of introducing the ink into the spinal column.
|-
| Pre-surgical checklist
| Might come in handy if/when going in for surgery. Surgeons do [https://www.bmj.com/content/331/7512/s56 mark patients prior to surgery] to prevent "wrong site" surgeries ("Oh, it was the ''right'' hip that needed replacing..."), but getting such markings as a tattoo would be unnecessary at best and dangerously misleading at worst.
|-
| Tattoo artist's Social Security number
| In the US, a {{w|Social Security number}} is a unique, nine-digit number assigned by the federal government to citizens and other legal residents. The original purpose of these numbers was to track Social Security accounts, for the payment of federal benefits. In practice, it is also widely used in other contexts in which an individual needs to be identified, including applications for loans, employment, and identity papers. As a result, learning someone's Social Security number is often a critical step in {{w|Identity Theft}}. People are often warned to safeguard their numbers and be very cautious about revealing them. Tattooing one's Social Security number on a customer would mean that both the customer and anyone who happened to see his tattoo in the future would have access to it. That would be a wildly reckless move which very few tattoo artists would be willing to make.
|-
| Boarding pass for an upcoming flight
| Useful only once, therefore not a normal design to have tattooed.
|-
| Recap of the plot of ''Memento''
| ''{{w|Memento (film)|Memento}}'' is a 2000 film in which the protagonist suffers from {{w|Anterograde amnesia|anterograde amnesia}}, a condition that prevents him from creating any new long-term memories. One of the tools he uses to mitigate the issue is tattooing important things on his body.
|-
| This list, in its entirety
| Instead of getting a tattoo of anything listed here, the actual list itself would be the tattoo.
|-
| The text ALL YOUR BASE ARE BELONG TO US with a lengthy footnote explaining that I got this tattoo in 2020 and not, as you may assume, 2001, but offering no further clarification. (title text)
| "{{w|All Your Base Are Belong to Us}}" was a popular internet meme from the early 2000s based on a broken English phrase found in the opening cutscene of the 1992 Mega Drive/Genesis port of the 1989 arcade video game ''Zero Wing''. The lengthy footnote denotes that the decision to get the tattoo was deliberate decision in 2020 and not a spur-of-the-moment decision while the meme was popular (in 2001). Making people question why somebody would make such a decision about such an old meme provides the humor.
|}

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:(In larger font and underlined, apparently the start of a list)
:Tattoo Ideas
:(A list, with all points but the last crossed out in red)
:Lorem Ipsum Text
:Email Password
:Graph of the popularity of tattoos over time, with the date I got the tattoo marked (update regularly)
:"Changeme"
:Slide Rule markings on forearms
:Eurion Constellation, so no one can photocopy pictures of me
:The sentence "it's what my tattoo says" written in another language
:Tissot's Indicatrix
:Summary of the Snopes page on the tattoo epidural thing (lower back)
:Pre-surgical checklist
:Tattoo Artist's Social Security Number
:Boarding pass for an upcoming flight
:Recap of the plot of ''Memento''
:(Last point in list, circled in red)
:This list, in its entirety

{{comic discussion}}
[[Category:Computers]]
[[Category:Fiction]]
[[Category:Programming]]

2255: Tattoo Ideas

2020-01-15T16:48:05Z

172.69.33.197: /* Table of entries */ copyedit

1654: Universal Install Script

2020-01-05T08:11:01Z

172.69.33.197: /* Trivia */ add categories

{{comic
| number = 1654
| date = March 11, 2016
| title = Universal Install Script
| image = universal_install_script.png
| titletext = The failures usually don't hurt anything, and if it installs several versions, it increases the chance that one of them is right. (Note: The 'yes' command and '2>/dev/null' are recommended additions.)
}}

==Explanation==
Most users of computers today are used to simple, easy installation of programs. You just download a {{w|.exe}} or a {{w|Installer_(OS_X)#Installer_package|.pkg}}, double click it, and do what it says. Sometimes you don't even have to install anything at all, and it runs without any installation.

However, when things are more "homebrew", for example downloading source code, things are more complicated. Under {{w|Unix-like}} systems, which this universal install script is designed for, you may have to work with "build environments" and "{{w|makefiles}}", and command line tools. To make this process simpler, there exist repositories of programs which host either packages of source code and the things needed to build it or the pre-built programs. When you download the package, it automatically does most of the work of building the code into something executable if necessary and then installing it. However, there are many such repositories, such as "{{w|pip (package manager)|pip}}" and "brew", among others listed in the comic. If you only know the name of a program or package, you may not know in which repository(ies) it resides.

The <code>install.sh</code> file provided in the comic is a {{w|shell script}}, which attempts to fix this problem by acting as a "universal install script" that contains a lot of common install commands used in various Unix-like systems. This script in particular is interpreted by the {{w|Bourne Again Shell}} (Bash), which is denoted by the <code>#!/bin/bash</code> in the first line. In between each of the install commands in the script is the & character, which in {{w|POSIX}}-compatible {{w|Unix shell|shells}} (including {{w|Bash (Unix shell)|Bash}}, a popular shell scripting language) means it should continue to run the next command without waiting for the first command to finish, also known as "running in the background". This has the effect of running all the install commands simultaneously; all output and error text provided by them will be mixed together as they are all displaying on the screen around the same time.

The script accepts the name of a program or package as an argument when you run it. This value is then referenced as "$1" (argument number 1). Everywhere the script says "$1", it substitutes in the name of the package you gave it. The end result is the name being tried against a large number of software repositories and package managers, and hopefully, at least one of them will be appropriate and the program will be successfully installed. Near the end, it even tries copying the source code from an online source and then runs several commands which compile/build the program.

All in all, this script would probably work; it runs many standard popular repository programs and package managers, and runs the nearly-universal commands needed to build a program. Most of the commands would simply give an error and exit, but hopefully the correct one will proceed with the install.

One of the more subtle jokes in the comic is the inclusion of <code>apt-get</code> and <code>sudo apt-get</code> in the same script. Good unix practice dictates never logging in as root; instead you stay logged in as your normal user, and run system admin accounts via <code>sudo program name</code>. This prevents accidental errors and enables logging of all sensitive commands. A side effect of this, however, is that an administrator may forget to prefix their command with <code>sudo</code>, and re-running it properly the second time. This is a common joke in the Linux community, an example of which can be found at this [https://twitter.com/liamosaur/status/506975850596536320 viral tweet] which shows a humorous workaround for the issue.

Since Randall's script does not use sudo for any but the <code>apt-get</code> command, there are two possibilities: the script itself was run via the root user or via sudo, in which case the <code>sudo apt-get</code> is not needed, or the script was run as a normal user, in this case the commands may install a local (as opposed to system-wide) version depending on local conditions. For instance npm will install a copy of the package under $HOME/.npm and pip would work as long as the user is working in a [https://iamzed.com/2009/05/07/a-primer-on-virtualenv/ virtualenv] (which is standard practice for Python developers).

Sudo has also been used both by [[Randall]] in [[149: Sandwich]] and by Jason Fox to force Randall to let him appear on xkcd with [[824: Guest Week: Bill Amend (FoxTrot)]].

The tool <code>curl</code> downloads files from the network (e.g., the Internet). For example, <code>curl http://xkcd.com/</code> downloads and displays the xkcd HTML source. The pipe <code>|</code> in the script attaches the output of the command before the pipe to the input of the command after the pipe, thus running whatever commands exist in the web content. Although this "curl|sh" pattern is a common practice for conveniently installing software, it is considered extremely unwise; you are running untrusted code without validation, there may be a MITM who modifies the code you receive, or the remote system could have been hijacked and the code made malicious. Most local package managers (e.g. <code>apt</code>, <code>yum</code>) offer digitally-signed packages that thwart this problem. You can find many examples of software providers suggesting a <code>curl|sh</code> solution at [https://curlpipesh.tumblr.com/ curlpipesh]

There appears to be a bug with the & at the end of the "git clone" line; since a git repository typically contains program source code, not executables, it may have been intended to retrieve the source code with git and then compile and install the program in the next line. In this case, the single & should be replaced with &&, an operator that will run the second command only if the first one has completed successfully. This plays into a second bug on the "configure" line, where the placement of the & means that only the "make install" command will be run asynchronously after the "configure" and "make" steps have finished in sequence (though this would likely fail due to a lack for write permissions unless it was run with sudo). To make success as likely as possible, the two lines should be like this or script should be executed twice:

git clone <nowiki>https://github.com/</nowiki>"$1"/"$1" && (cd "$1"; ./configure; make; sudo make install) &

Since all commands are running in the background, any command that requires user input will stop and wait until brought to the foreground. A common request would be for a database password, or if it is allowed to restart services for the installation. This could lead to packages being only partly installed or configured. (See more about using "yes" below.)

The title text mentions the possibility that the same program may be in multiple repositories, so in this case, the script will download and install several versions, or it may fail on a number of repositories, in which case usually nothing bad happens. Since all the commands come from different operating systems, versions, or distributions, it is not very likely that more than one will work (with the exception of pip/easy_install and the two forms of apt-get) or even exist on the same system. It mentions that adding a way of automatically saying "yes" to questions asked during the different repository-fetching programs' running, by making them read input from another program that writes a (nearly) endless stream of "y"s, could simplify things further. This would not work for any curses-based menus, or to answer any more complicated questions. Adding <code>2>/dev/null</code> to a command redirects the second output stream (the "error stream") to the null device driver, which discards all writes to it, meaning errors (the package not existing) will not be sent to the screen.

==Transcript==
:[In the panel is a shell script which, unusual for xkcd, uses only lower case. At the top the title of the program is inlaid in the frame, which has been broken here.]
:<big>Install.sh</big>

:<nowiki>#!/bin/bash</nowiki>

:pip install "$1" &
:easy_install "$1" &
:brew install "$1" &
:npm install "$1" &
:yum install "$1" & dnf install "$1" &
:docker run "$1" &
:pkg install "$1" &
:apt-get install "$1" &
:sudo apt-get install "$1" &
:steamcmd +app_update "$1" validate &
:git clone <nowiki>https://github.com/</nowiki>"$1"/"$1" &
:cd "$1";./configure;make;make install &
:curl "$1" | bash &

==Trivia==
*pip and easy install are package managers for {{w|Python (programming language)|Python}}
*brew is the successor/replacement for {{w|MacPorts}} and a third-party package manager for OS X
*{{w|npm (software)|npm}} is the node package manager that maintains node.js packages
*{{w|Yellowdog Updater, Modified|yum}} is the package management tool for {{w|Red Hat Enterprise Linux}} and some derivatives
*{{w|DNF (software)|dnf}} is the package management tool for {{w|Fedora (operating system)|Fedora}} since version 22
*docker run is a {{w|Docker (software)|Docker}} command that runs a given container (similar to a virtual machine)
*pkg is the package management tool on {{w|Berkeley Software Distribution|BSD systems}}
*apt-get is the package management tool of {{w|Debian}} and derivatives (e.g. Ubuntu)
*steamcmd refers to the command line version of {{w|Steam (software)|Steam}}, the computer game client
*git is the revision control software used for many projects and gained a lot of traction through the {{w|GitHub}} platform
*configure/make/make install refers to the standard way of compiling software from source (on Linux/Unix)
*curl is a tool for loading data via http:// (i.e. from a website), this data is then pushed to the shell interpreter (in order to install)
**Note: While this is a security nightmare, some projects (like Homebrew) still use it as the preferred or only method of installation.
* a similar comic is {{xkcd|1987}} which concerns only Python.

{{comic discussion}}
[[Category:Linux]]
[[Category:Programming]]
[[Category:Version Control]]

1667: Algorithms

2020-01-05T08:09:52Z

172.69.33.197: /* Transcript */ add catgeory

{{comic
| number = 1667
| date = April 13, 2016
| title = Algorithms
| image = algorithms.png
| titletext = There was a schism in 2007, when a sect advocating OpenOffice created a fork of Sunday.xlsx and maintained it independently for several months. The efforts to reconcile the conflicting schedules led to the reinvention, within the cells of the spreadsheet, of modern version control.
}}

==Explanation==
An algorithm is a basic set of instructions for performing a task, usually on a computer. This comic lists some algorithms in increasing order of complexity, where complexity may refer to either {{w|computational complexity theory}} (a formal mathematical account of the {{w|computational resource}}s – primarily computation time and memory space – required to solve a given problem), or the more informal notion of {{w|programming complexity}} (roughly, a measure of the number and degrees of internal dependencies and interactions within a piece of software).

At the simplest end is '''left-pad''', or adding filler characters on the left end of a string to make it a particular length. In many programming languages, this is one line of code. This is possibly an allusion to a [http://www.haneycodes.net/npm-left-pad-have-we-forgotten-how-to-program/ recent incident] when {{w|Npm (software)|NodeJS Package Manager}} [https://www.techdirt.com/articles/20160324/17160034007/namespaces-intellectual-property-dependencies-big-giant-mess.shtml angered a developer] in its handling of a trademark claim. The developer unpublished all of his modules from NPM, including a package implementing left-pad. A huge number of programs depended on this third-party library instead of programming it on their own, and they immediately ceased to function.

'''{{w|Quicksort}}''' is an efficient and commonly used {{w|sorting algorithm}}.

'''{{w|Git (software)|Git}}''' is a {{w|version control}} program, i.e., software that allows multiple people to work on the same files at the same time. When someone finalizes ("commits") their changes, the version control program needs to join the new content with the existing content. When more than one person has made overlapping changes at the same time, the process of figuring out how to join them is called '''{{w|Merge (version control)|merging}}''', and the algorithm for it is anything but simple.

A '''{{w|self-driving car}}''' is an automobile with sensors and software built into it so that it can maneuver in traffic autonomously, i.e. without a human controller. Various companies have been working on such vehicles for many years now, and while they're further along now than would have been imaginable even a couple of years ago, we're still far away from the dream of hopping in a driver-less taxi and sitting back as the car itself navigates to where we want to be. Recently [[Randall]] has made several references to self-driving cars which has become a [[:Category:Self-driving cars|recurring topic]] on xkcd.

The '''{{w|Google Search}} backend''' is what enables you to type "what the heck is a leftpad algorithm" into your browser and have Google return a list of relevant results, including correcting "leftpad" to "left-pad", truncating "what the heck is" to simply "what is", and sometimes even summarizing the findings into a box at the top of the results. Behind all that magic is a way to remember what pages the Internet contains, which is just a mind-bogglingly large quantity of data, and an even more mind-numbingly complex set of algorithms for processing that data.

The last item is the punchline: a sprawling {{w|Microsoft Excel|Excel}} {{w|spreadsheet}} built up over 20 years by a church group in Nebraska to coordinate their scheduling. Spreadsheets are a general {{w|end-user development}} programming technique, and therefore people use Excel for all sorts of purposes that have nothing to do with accounting (its original purpose), including one guy who made a [http://arstechnica.com/gaming/2013/04/how-an-accountant-created-an-entire-rpg-inside-an-excel-spreadsheet/ role-playing game that runs in Excel]; but even that doesn't approach the complexity that develops when multiple people of varying levels of experience use a spreadsheet over many years for the purpose of coordinating the schedule of several coordinated groups.

The scheduling of tasks over a group of resources (a.k.a. the ''{{w|nurse scheduling problem}}''), while respecting the constraints set by each person, is a {{w|NP-hardness|highly complex}} problem requiring stochastic or heuristic methods for its resolution. Here, the algorithm would be further complicated by being solved by inexpert users over a spreadsheet model without using engineering practices. The potential hyperbole here is in thinking that such combination of circumstances would produce complexity far over that required to drive a car or sort the public contents of the Internet. While most churches meet mainly on Sunday morning, scheduling of what happens during the service when (especially if there are multiple concurrent services) as well as Sunday School, church business meetings, and congregation-wide events all potentially needing to be scheduled on a particular Sunday morning, the need to find a solution very close to the best possible solution quickly becomes a dire need. Furthermore, with different members involved in a wide variety of activities within and outside of the church, and the classrooms available to the church on Sunday itself, (just scheduling the choir practice times to coordinate with everyone's work schedules is very possibly impossible, especially if two people share the same occupation, and one is the relief for the other,) can indeed be daunting. In addition, there would likely be assorted committee meetings and youth groups during the week.

In the title text, part of the spreadsheet's complexity is described as originating from different versions of the file for different programs. The words used like {{w|schism}} and {{w|sect}} are normally used in context of religions splitting into groups about differences in beliefs. In this case, the split seems to have been not over a {{w|theology|theological}} issue, but about the use of {{w|open-source software|open-source}} vs. {{w|proprietary software|proprietary}} software, disagreements about which are often compared to religious debates. Most likely, the schism being referred to is the {{w|East–West Schism|East-West Schism of 1054}}.

The title text also implies that while trying to reconcile after the schism and to merge the two schedules they reinvented an alternative to Git within the spreadsheet itself, making the algorithms in place at least as complicated as that. Since most spreadsheet programs have a sort algorithm built in, that aspect is implied too, and left-padding could be compared to vamping on an introduction to a hymn. This would indicate that the other milestones of complexity are either included in the current version of the spreadsheet or are planned to be implemented.

==Transcript==
'''Algorithms''' By Complexity
{|
|colspan="6" style="text-align:left;border-bottom:1px solid;"|More complex →
|- style="vertical-align:top;"
|style="padding-right:2em;"|Leftpad
|style="padding-right:2em;"|Quicksort
|style="padding-right:2em;"|GIT Merge
|style="padding-right:2em;"|Self- driving car
|style="padding-right:8em;"|Google Search backend
|Sprawling Excel spreadsheet built up over 20 years by a church group in Nebraska to coordinate their scheduling
|}

{{comic discussion}}

[[Category:Charts]]
[[Category:Google Search]]
[[Category:Programming]]
[[Category:Religion]]
[[Category:Self-driving cars]]
[[Category:Spreadsheets]]
[[Category:Version Control]]

624: Branding

2020-01-05T08:09:16Z

172.69.33.197: /* Transcript */ add category

{{comic
| number = 624
| date = August 17, 2009
| title = Branding
| image = branding.png
| titletext = Actually, 'RSS&M' is kinda catchy.
}}

==Explanation==
This comic pokes fun at web sites (adult-themed sites in particular) which try to inflate their popularity by comparing themselves to other popular online services. The strip shows four such advertisements that appear to [[Cueball]] as he browses the Internet.

{{w|Adblock}} is a browser extension which prevents advertisements from being displayed. Presumably Cueball normally browses the Internet with Adblock enabled, and thus would not see any of these ads.

The first advertises a website that brands itself as the "{{w|Facebook}} of sex". Because Facebook is ubiquitous, this is a good branding idea. Facebook is known to most users and connotes an easy-to-use platform where it's very easy to find people, chat with them, share pictures, etc. For someone looking for sex, this would probably seem like a good site to use. There are, in fact, sites that use this branding in their advertisements and/or their user interface which is likely what inspired [[Randall]] to write this comic. Cueball sighs and moves on, probably having seen this kind of ad many times already.

The second brands itself as "Twitter for 18+ singles". It is a similar but seemingly invented ad which again plays on the ubiquity and popularity of {{w|Twitter}}. Twitter being a (generally) public chat forum which at the time this comic was published limited posts to 140 characters is still popular enough to get some attention and make someone think about going to the site. Sending messages to the world in 140 characters or less might be somewhat less of a versatile platform than Facebook for chatting with other singles, but still perhaps viable. Cueball notes that it is becoming more and more popular to brand adult sites by comparing them to popular non-adult sites.

This third takes a turn for the unusual, branding itself as "Google Reader for S&M". {{w|Google Reader}} is a now-defunct platform that allowed users to aggregate web feeds such as RSS feeds into one place for convenience. The service is notably less well-known and popular than Facebook or Twitter, and given that it doesn't directly link you with other people, doesn't have the same connotation of allowing you to connect with others. Perhaps it would be a site that allowed you to aggregate various fan fictions, blogs, or other written works relating to {{w|Sadomasochism|S&M}}. However, Cueball is surprised such a site would exist.

The final ad brands itself as a "GitHub for lesbians". {{w|GitHub}} is a website that allows developers to collaborate on software projects using the {{w|Git (software)|Git}} revision control system. The concept is absurd — GitHub has a specialized function unrelated to anyone's gender or orientation, and it's barely a social network at all; the usefulness or appeal of such a system made specific to lesbians is not apparent. Cueball is surprised and possibly even intrigued by this last ad.

The title text relates to the third panel. {{w|RSS}} is a technology involved in Google Reader. RSS&M is a portmanteau of RSS and S&M. This is a possible way for the third web site to brand itself.

==Transcript==
:Browsing without adblock
:[Cueball is sitting at a computer.]
:[Pop-up window with red background.]
:The Facebook of SEX! Click now!
:Cueball: Sigh.
:<nowiki>*Close*</nowiki>

:[Pop-up window with green background.]
:Twitter for 18+ singles! Join today!
:Cueball: Does every porn site have to brand itself like this?
:<nowiki>*Close*</nowiki>

:[Pop-up window with blue background.]
:We're like Google Reader for S&M!
:Cueball: ''Really?''
:<nowiki>*Close*</nowiki>

:[Pop-up window with orange background.]
:Try the new GitHub for lesbians!
:Cueball: Ok, wait, what?

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics with color]]
[[Category:Internet]]
[[Category:Portmanteau]]
[[Category:Sex]]
[[Category:Social networking]]
[[Category:Version Control]]

1597: Git

2020-01-05T08:08:29Z

172.69.33.197: /* Transcript */ add category

{{comic
| number = 1597
| date = October 30, 2015
| title = Git
| image = git.png
| titletext = If that doesn't fix it, git.txt contains the phone number of a friend of mine who understands git. Just wait through a few minutes of 'It's really pretty simple, just think of branches as...' and eventually you'll learn the commands that will fix everything.
}}

==Explanation==
===This is Git===
{{w|Git (software)|Git}} is a version control system, used to manage the code in many millions of software projects. It is very powerful, and was amongst the first widely adopted tools to use a distributed version control model (the "beautiful {{w|graph theory}} {{w|Tree (graph theory)|tree model}}"), meaning that there is no single central repository of code. Instead, users share code back and forth to synchronise their repositories, and it is up to each project to define processes and procedures for managing the flow of changes into a stable software product.

===How do we use it?===
Although very powerful, the command line of Git is notoriously difficult to learn and master. Dozens of blog posts and websites (see [http://think-like-a-git.net/epic.html], [http://stevebennett.me/2012/02/24/10-things-i-hate-about-git/]), and even books ([http://blog.anvard.org/conversational-git/chapter-01.html], [http://git-scm.com/book/en/v2]) have been written to help users navigate this complexity.

The difficulty of using Git in common situations is contradicted by the apparent simplicity of its use in tutorial-style situations. Committing and sharing changes is fairly straightforward, for instance, but recovering from situations such as accidental commits, pushes or bad merges is difficult without a solid understanding of the rather large and complex conceptual model. For instance, three of the top five highest voted questions on Stack Overflow are questions about how to carry out relatively simple tasks: undoing the last commit, changing the last commit message, and deleting a remote branch.

This comic thus explores the difference between the idealised view of Git's architecture, and its actual typical usage. Tutorials for Git tend to use simple systems in their examples, and only deal with the most basic commands to get started, which can create the misleading impression that Git can be used effectively without extensive study.

Due to this problem, compounded by the fact that Git's commands are named differently from similar commands in other version control systems, many users (including Cueball) are unable to use it beyond basic commands, and might try to avoid problems by saving their code outside Git, downloading a newer copy, and then re-applying their changes to the new copy instead of trying to understand and use the features that exist in Git to accomplish this task.

===Memorize these shell commands===
Cueball suggests "just memoriz[ing] these shell commands and type them to sync up". He is probably referring to a sequence of commands such as:

git pull
# remote changes have now been received, so work on your file
git add file.txt
git commit -m "Added some text"
git push

===If you get errors...===
As long as every contributor to the project follows these principles, this may suffice for a while. But many situations may cause "errors":

* merge conflicts (two people editing the same part of the same file)
* unmerged changes (another person committed a change before you did, so you need to merge their changes first)
* attempting to recover from a situation such as an accidental merge, and making the situation worse.

In a situation such as a merge conflict, Git will show an error message such as:

CONFLICT (modify/delete): README.md deleted in HEAD and modified in branch-b. Version branch-b of README.md left in tree.
# Automatic merge failed; fix conflicts and then commit the result.

===Save your work elsewhere...===
Although Git experts can of course deal with such situations, the remedy proposed by Cueball is "save your work elsewhere, delete the project, and download a fresh copy". That is, to copy the files out of their local repository's working directory, delete that whole structure, then clone the remote repository again (and, implicitly, copy the saved work back again):

# Copy files elsewhere
mkdir /tmp/myproject
cp * /tmp/myproject
cd ..
# delete the project
rm -rf myproject

# Download a fresh copy
git clone https://github.com/myorg/myproject
cd myproject

# Copy saved work
cp /tmp/myproject/* .

Abandoning the old project likely means losing some work, but may be faster and give a more predictable outcome than attempting to salvage the situation. Applying this method to a mere merge conflict issue may prolong the issue however, as the merge conflicts may still be present.

===Title text===
The title text suggests an alternative method for working around Git's complexities, which reflects common practice: knowing a "Git expert" who can help in any situation. Such experts are somewhat notorious for waxing lyrically about Git's strengths, so it may be necessary to win their favour by first letting them ramble enthusiastically about it. They will hopefully eventually give the exact commands needed. In practice, the question-and-answer site Stack Overflow is frequently used for this exact purpose.

It may even be a reference to the infamous tweet "[https://twitter.com/agnoster/status/44636629423497217 Git gets easier once you get the basic idea that branches are homeomorphic endofunctors mapping submanifolds of a Hilbert space]" which has been [http://www.beyondjava.net/blog/git-explained-in-really-simple-words/ discussed here] but it is inconclusive whether a meaningful interpretation exists.

Putting a telephone number of someone who "understands Git" into such a file is humorous because:
*Software teams would more normally use electronic means of communication
*Explaining Git over the phone to team members should not be necessary, as there is extensive help available online, and
*In the situation where many team members would need phone support to avoid or fix basic Git problems, this would be extremely distracting to the person whose phone number was given in the file.

=== TL;DR===
In short: programmers use {{w|Version control|version control systems}} to track changes to code. Most of these version control systems are quite similar and easy to learn if you already know another one. Git is a version control system based on completely different principles, and most programmers find it difficult to wrap their heads around it (although Git also offers a large number of nontrivial benefits over standard version control systems, which is why it is used). Cueball is one of those programmers.

== Trivia ==

This comic was referenced in an earlier version of the page for ''what if?'' #153, where Randall, due to a problem with git, had at one time erroneously posted a draft of his [[what if?]] piece on peptides. As of December 17th, 2016 the page read:

:;Whoops
:This article is still in progress. An early draft was unintentionally posted here thanks to Randall's {{xkcd|1597|troubled approach to git}}, and it took a little bit to get everything sorted out and rolled back. Sorry for the mixup!

On January 30, 2017, the page was updated with a completed article, ''{{what if|153|Hide the Atmosphere}}''. As of September 23, 2019, the page no longer contains any reference to this comic or Randall's earlier mistake with Git (or anything related to Git, for that matter).

The comic [[1296: Git Commit]] also features Git.

==Transcript==
:[Cueball points to a computer on a desk while Ponytail and Hairy are standing further away behind an office chair.]
:Cueball: This is git. It tracks collaborative work on projects through a beautiful distributed graph theory tree model.
:Ponytail: Cool. How do we use it?
:Cueball: No idea. Just memorize these shell commands and type them to sync up. If you get errors, save your work elsewhere, delete the project, and download a fresh copy.

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Hairy]]
[[Category:Computers]]
[[Category:Programming]]
[[Category:Version Control]]

1296: Git Commit

2020-01-05T08:07:48Z

172.69.33.197: /* Transcript */ add category

{{comic
| number = 1296
| date = November 27, 2013
| title = Git Commit
| image = git_commit.png
| titletext = Merge branch 'asdfasjkfdlas/alkdjf' into sdkjfls-final
}}

==Explanation==
This comic refers to the {{w|Git (software)|Git}} source code revision control software, which saves earlier versions of files and folders for later access into a special repository. This comes handy when you want to try out whether an idea works (branching). Further, you can collaborate with others by use of remote repositories. Perhaps most importantly, it allows members of the development team to find key changes in the history, later. Git has been discussed in [[1597: Git]] as well.

A {{w|wikt:commit#Noun|''commit''}} is a saved version in a Git repository; a commit comes with a message that is supposed to describe what the commit contains, similar to the edit summaries used on {{w|MediaWiki}} sites such as ''explain xkcd'' and on [http://www.explainxkcd.com/wiki/index.php?title=1296:_Git_Commit&action=history this explanation]. [[Randall]], however, finds himself losing interest in the commit messages the more code he writes and winds up just using placeholder text or jokes to himself. Presumably, this is because his separate commits are part of a large effort that can't be effectively summarized, and where there's no particular urgent need to differentiate the commits. Seeing as in this context 12 hours of coding can be considered "dragging on," it's safe to assume that the kinds of commits Randall is talking about are not for some major in-production project, nor for something that a lot of other people are working on. In both of those cases, one would be much more likely to use descriptive commit messages, since you want to flag things that are important, either from a technical standpoint (e.g. "fix the thing that's making the site not work") or for the benefit of others who want to know which commits they should be paying attention to.

The phrase "Merge branch 'asdfasjkfdlas/alkdjf' into sdkjfls-final" mimics the phrasing used by Git. A ''branch'' is a specific sequence of commits which can be made in parallel to other branches of development, and later merged. Here, we see that Randall has also gotten lazy with his branch names: "branch 'asdfasjkfdlas/alkdjf'" might be the series of two commits starting with "here have code". "sdkjfls-final" could be the branch indicated by the vertical string of circles on the left, into which the other more branch is merged in commit "adkfjslkdfjsdklfj".

Most git tools show the commit history with the most recent commits first, so showing the oldest first like this would require something like the <code>--reverse</code> option.

The comments go from being pretty detailed as to his thoughts and reasons for the code ("enabled config file parsing"), to relatively uninformative summaries ("misc bugfixes"), to completely uninformative words ("more code"), and then finally he doesn't even bother trying to come up with words, instead just hitting a key ("aaaaaaaa") or semi-random keys ("adkfjslkdfjsdklfj"), then goes back to typing words but words that have a bit of a craziness to them rather than having anything to do with describing the code ("my hands are typing words"). The "adkfjslkdfjsdklfj" line and similar garbage in the title text comes from having your hands on the "{{w|home row}}" on a standard {{w|QWERTY}} keyboard, then hitting "random" keys without moving your fingers from their standard home row positions. The keys you hit "randomly" will be combinations of A, S, D, and F on the left hand, and J, K, L, and ; on the right hand (although the ; key seems to have been avoided, possibly because without the presence of surrounding quotes a ; character will end the comment). It is common to see stuff like that when a person is required to type something — i.e. a mandatory field — but they have no interest in typing anything meaningful or no idea what to write, so they just hit the easiest keys to hit and call it done.

==Transcript==
{| class="wikitable"
! 
!Comment
!Date
|-
|(main)||created main loop & timing control||14 hours ago
|-
|(main)||enabled config file parsing||9 hours ago
|-
|(main)||misc bugfixes||5 hours ago
|-
|(main)||code additions/edits||4 hours ago
|-
|(main)||more code||4 hours ago
|-
|(branch)||here have code||4 hours ago
|-
|(branch)||aaaaaaaa||3 hours ago
|-
|(main)||adkfjslkdfjsdklfj||3 hours ago
|-
|(main)||my hands are typing words||2 hours ago
|-
|(main)||haaaaaaaaands||2 hours ago
|}
:[Caption below the panel:]
:As a project drags on, my Git commit messages get less and less informative.

{{comic discussion}}
[[Category:Comics with color]]
[[Category:Programming]]
[[Category:Version Control]]

Category:Version Control

2020-01-05T08:07:19Z

172.69.33.197: Git category was removed

Comics that are about {{w|version control}}.

[[Category:Programming]]

2249: I Love the 20s

2020-01-01T22:17:55Z

172.69.33.197: Dionysius Exiguus screwed up the calendar; centuries should begin and end in the mid '90s

{{comic
| number = 2249
| date = January 1, 2020
| title = I Love the 20s
| image = i love the 20s.png
| titletext = Billboard's "Best of the 80s" chart includes Blondie's 1980 hit "Call Me." QED.
}}

==Explanation==
{{incomplete|Created by a PEDANT. Explain title text.}}
This comic was released on the first day of {{w|2020}}. [[Megan]], [[Cueball]], and [[Ponytail]] are all happy for the beginning of the new {{w|decade}}, for a variety of reasons. However, [[White Hat]] disagrees, claiming that the "20s" don't start until 2021, citing that {{w|Century|centuries}} are "off-by-one" (for instance, the {{w|20th century}} lasted from 1901 through 2000) and attempting to draw something, presumably a number line that starts with "Year 1" as the Anno Domini / Common Era years do. Ponytail's argument is that, while centuries are numbered ordinally (traditionally, the First Century starts in year 1 and ends in the year 100, the Second Century starts in the year 101 and runs through the year 200, and so on, because {{w|Zero-based numbering|zero indexing}}, like the number zero itself, was not in wide use at the time; however, due to an error by {{w|Dionysius Exiguus}}, the year 1 was after the death of {{w|Herod the Great}}, so Jesus could not have been born in that year, and was probably born either in 4 B.C. or 6 B.C., so the first, second, etc., century after his birth would actually end in the mid '90's), decades are more commonly delimited by the tens digit. For example, the {{w|Roaring Twenties}} are the years whose three most significant digits are 192, running from 1920 through 1929 (sometimes said to end slightly before the end of 1929, with the onset of the {{w|Great Depression}} in October 1929). Nobody{{Citation needed}} refers to this time as "the 193rd decade", which would run from 1921 through 1930.

Megan breaks up their heated argument by stating that {{w|MC Hammer}}'s song ''{{w|U Can't Touch This}}'', released in 1990, was featured in a 1990s-themed television show instead of its 1980s-themed counterpart.

==Transcript==
{{incomplete transcript}}

:[Megan, Cueball, White Hat, and Ponytail stand in frame.]
:Megan: Happy new decade!
:Ponytail: Welcome to the '20s!
:White Hat: ''Actually—''
:Ponytail: I'm excited we can name decades again.
:Ponytail: "Aughts" and "teens" never caught on.

:White Hat [raising a finger]: Actually, the new decade doesn't start--
:Ponytail: Mostly, I'm just glad we can go back to attributing cultural trends to decades instead of generations.

:Cueball: Yeah.
:Cueball: Decades were silly, but making everything about "millennials" turned out to be even worse.
:Ponytail: Seriously.

:[The panel zomms in, displaying only White Hat and Ponytail.]
:White Hat: It's technically not a new decade until 2021.
:Ponytail: OK, listen.
:Ponytail: If you're going to be pedantic, you should at least be right.
:White Hat: I ''am'' right!
:Ponytail: You're ''not''.

:[White Hat and Ponytail gesture towards each other.]
:White Hat: See, the 20th century didn't start until--
:Ponytail: But decades aren't centuries. They're not cardinally numbered.
:White Hat: You don't get it. Let me draw a--
:Ponytail: No, ''you'' don't--
:Megan (off-panel): Stop!

:[All four characters are displayed again. Megan has raised a finger.]
:Megan: I can resolve this.
:Megan: *ahem*
:Megan: MC Hammer's ''U Can't Touch This'' (1990) was featured in ''I Love the '90s'', not '''80s''.
:Ponytail: ...That settles that.
:White Hat: Yeah, I accept VH1's authority.
:White Hat: You win.

{{comic discussion}}

[[Category:Comics featuring Megan]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring White Hat]]
[[Category:Comics featuring Ponytail]]

Talk:2243: Star Wars Spoiler Generator

2019-12-19T19:26:41Z

172.69.33.197: Added link to C#/LINQ implementation.

I made this JavaScript implementation of the generator: https://codepen.io/qgustavor/full/gObgBxo [[Special:Contributions/172.68.24.70|172.68.24.70]] 22:33, 18 December 2019 (UTC)
:there are some words that should be capitalized: First Order, Sith, Force, Jawa... Also ochre is misspelt and colors should NOT be capitalized. Thanks![[Special:Contributions/141.101.98.196|141.101.98.196]] 10:21, 19 December 2019 (UTC)

who said that the rise of skywalker would be released two days before the publishing date after stating that it's going to be released on the twentieth?

Re: Malloc, there was also a Darth Malak, the antagonist of Star Wars Knights of the Old Republic and a recurring character in the Old Republic comics [[Special:Contributions/172.69.69.244|172.69.69.244]] 02:08, 19 December 2019 (UTC)47.221.57.204

Should something be linked to about diectric breakdown, or is that considered obvious in the context of, er, Force lightning? Also, am I remembering right that Dark Helmet, in Spaceballs, wears a smaller helmet with a really big helmet over it? Maybe not! Robert Carnegie rja.carnegie@gmail.com [[Special:Contributions/141.101.98.250|141.101.98.250]] 02:48, 19 December 2019 (UTC)

There are a couple of posts to be found online that refer to "Darth Sebelius" in the context of Obamacare, but they're all on pretty niche forums. --[[User:NotaBene|NotaBene]] ([[User talk:NotaBene|talk]]) 03:07, 19 December 2019 (UTC)

Perchance generator: https://perchance.org/q3wi2jqf0j [[Special:Contributions/173.245.54.59|173.245.54.59]] 03:16, 19 December 2019 (UTC)

For a less US-centric view, the movie was released officially in France and Norway (and probably also other countries) already on the 18.12. (that is December 18). So "On December 20, 2019 [...], the final movie [...] will be released." should say "[...] will be released in the US."[[Special:Contributions/162.158.134.220|162.158.134.220]] 12:01, 19 December 2019 (UTC)

Another generator: http://xkcd-2243.surge.sh/

I don't know enough to add to the actual page, but the Sith car wash reminded me of this. Perhaps it was also part of the inspiration for it? https://www.cnet.com/roadshow/news/tesla-laser-windshield-wiper-patent/ [[Special:Contributions/141.101.69.35|141.101.69.35]] 15:28, 19 December 2019 (UTC)

"A New Hope" should just be called "Star Wars". [[Special:Contributions/141.101.76.16|141.101.76.16]] 18:58, 19 December 2019 (UTC)

C#/LINQ: https://dotnetfiddle.net/r0JMJz

2241: Brussels Sprouts Mandela Effect

2019-12-13T23:00:58Z

172.69.33.197:

{{comic
| number = 2241
| date = December 13, 2019
| title = Brussels Sprouts Mandela Effect
| image = brussels_sprouts_mandela_effect.png
| titletext = I love Brussels Sprouts Mandela Effect; I saw them open for Correct Horse Battery Staple.
}}

==Explanation==
{{incomplete|Created by a TASTY BRUSSELS SPROUT. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

I always thought of Brussels sprouts as terrible, but they're actually really good! I can't believe I let everyone mislead me!

It's not just you! Farmers developed a less-bitter cultivar like 15 years ago.*

*npr.org/773457633

Now the whole world is having this revelation, one person at a time. It's like a real mandela effect. We secretly switched to the parallel universe where Brussels sprouts taste good.

Cool.

Also, licorice is good now.

Whoa, really?

This is a trap.

And those silica gel packets that say "do not eat"? Delicious.

I knew it.

{{comic discussion}}

1882: Color Models

2019-12-04T00:53:41Z

172.69.33.197: /* Transcript */ this is science-related

{{comic
| number = 1882
| date = August 28, 2017
| title = Color Models
| image = color_models.png
| titletext = What if what *I* see as blue, *you* see as a slightly different blue because you're using Chrome instead of Firefox and despite a decade of messing with profiles we STILL can't get this right somehow.
}}

==Explanation==
[[Randall]] is describing how his level of understanding of colors has changed by age. The chart starts with two tracks of understanding color.

In grade school he learned about the primary colors, and the very simple model of colors, as shown in the left track. Mixing of color solids, as in painting (or finger painting being probably the earliest exposure to color mixing), is intuitive for a child. The process is subtractive, and the more colors you mix the darker and closer to black you get. Color is seen by the eyes when light bounces off the solid colors and becomes light of different wavelengths that the eye can then see. However at this level, things just "look" like different colors without understanding light's role. The color models mentioned in the second point of the left track are the additive model {{w|RGB}} (red-green-blue) and the subtractive models {{w|RYB}} (red-yellow-blue) and {{w|CMYK}} (cyan-magenta-yellow-key, used in color printing).

The right track is about mixing of colored light, as in prisms and light waves, where mixing colors is additive and the more you mix the lighter and closer to white you get. But this is without a real understanding of light bouncing off surfaces, and is limited to an understanding of different colors of light and how they mix. The first exposure in grade school is usually by shining white light through a prism to separate it into the different visible colors.

Meanwhile, philosophically, color is unknowable because it's impossible to say if everyone has the same qualia for colors. E.g. "Maybe what I see as blue, you see as my idea of purple, but we both call it blue because we've been brought up to know to call that color blue?."

The {{w|Opponent process|opponent color model}} connects these two models, by considering how the signals from rods and cones are processed, after different wavelengths of light are absorbed by different rods and cones in the eyes.

The "complex multidimensional gamut" mentions two more models: {{w|CIE 1931 color space|CIE 1931}} and {{w|Lab color space|L*a*b*}}. These are more detailed models based on the opponent color model, which precisely define how a particular color maps to the different channels that our eyes see.

However, understanding how the eye sees color ''still'' isn't enough, because not every device can display all the colors your eye can see. Your laptop might have a different {{w|Gamut|gamut}} from that of your phone, and when you print the page, you might see yet another color. To handle this issue, web browsers use "color profiles", so that an image can be tagged with the color space it uses and the browser can handle it appropriately. Unfortunately, browsers do this inconsistently and not very well.

Further complicating the matter, ostensibly identical device may show colors differently (depending on how they are adjusted, variations between devices, aging of the device, and the viewing environment). Devices and software exist to attempt to match systems to reproduce colors consistently, however most systems are not set up this way, color correction can be complicated, and the corrections have to be frequently readjusted.

The "hyperdimensional four-sided quantum Klein manifold" is a joke, and could also be a pun upon the color {{w|International Klein Blue|Klein Blue}}. A ''Klein manifold'' is described by the {{w|Klein bottle}}, where the bottle was originally a surface (a mix-up of the German words Fläche for surface and Flasche for bottle). It is a two-dimensional manifold, or simply just a surface with some special characteristics. Randall is here projecting an "abstract multidimensional gamut" onto an even more complicated surface, presumably in order to eliminate the errors in color rendering caused by previous attempts to eliminate the errors in color rendering. The Klein bottle has to be projected into 4 dimensional (4-D) space for this to work, as it would otherwise intersect with itself.
The “quantum” may be a reference to the "color" charge in {{w|Quantum chromodynamics}}.

Eventually it appears Randall has given up, realizing color is very difficult and hoping somebody else will deal with the difficulty in describing, understanding and using the concept of colors.

The title text expands on this joke, implying that the reason for the "unknowable" answer in the cartoon is that everyone's browser shows colors slightly differently. Despite the complexity and thoroughness of color models, this common software can't get it right.

==Transcript==
:[A simple flowchart is shown. The text above the panel reads:]
:Evolution of my understanding of color over time:

:[On the left side is a vertical dashed line in gray, on top it's labeled:]
:Grade school
:[And at the bottom the label reads:]
:Now

:[Header above the chart:]
:"Color" is...

:[The chart starts with three items, one left and an other on the right, a third is below in the middle.]
:...three primary colors mixed together
:...a rainbow, and each color is a wavelength
:...unknowable ("maybe what ''I'' see as blue, ''you'' see as...")

:[Arrows from the left and the middle item point to a new left one, while two other arrows from the middle and the right item lead to one at the right.]
:...three-ish primary colors mixed together (RGB/RYB/CMYK)
:...a mix of infinite wavelengths filtered through three eye pigments

:[The arrows of both items point to one in the middle:]
:(something about the opponent color model)

:[The remaining items are all in the middle and each is connected by one arrow downwards to the next.]
:...an abstract multidimensional gamut (CIE 1931, L*a*b*, etc)
:...an abstract multidimensional gamut filtered through inconsistently-implemented device color profiles
:...a hyperdimensional four-sided quantum Klein manifold? Is that a thing?
:...hopefully somebody else's problem.

{{comic discussion}}

[[Category:Flowcharts]]
[[Category:Science]]

2236: Is it Christmas?

2019-12-02T23:13:30Z

172.69.33.197: /* Explanation */ working now?

{{comic
| number = 2236
| date = December 2, 2019
| title = Is it Christmas?
| image = is_it_christmas.png
| titletext = We've tested it on 30 different days and it hasn't gotten one wrong yet.
}}

==Explanation==
{{incomplete|Created by a BOT (99.73% accurate). Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}
Here Randall has made a comic which nearly always correctly tells if it is Christmas. This also works for any annual event lasting only one day.

Randall lists a rounded calculation of 99.73%. If we calculate without leap years, 364/365 shows 99.726027397‬% accuracy. Calculating with leap years gives 364.2425/365.2425: approximately 99.726209299%. Or running the calculation on just a leap year gives 365/366 (99.7267759562%). Because all three numbers round up to 99.73%, the listed percentage is correct all three ways.

Although Randall's claim on {{w|Accuracy and precision#In binary classification|accuracy}} is true, accuracy alone doesn't make a predictive device useful. In this case, the page {{w|False positives and false_negatives#false negative rate|miss rate}} or false negative rate, that is, the percent of positive condition days (it's Christmas) that are predicted by the comic not to be Christmas, is 100%. In other words, it misses all actual events of Christmas. A reasonably useful prediction, however, should be likely to say "No" when it is not Christmas - as Randall's one does - but it should also be likely to say "Yes" when it's Christmas - which Randall's one doesn't.

In fact, in most settings where a single outcome is a lot more common than any other one, predicting always that most common outcome would yield very high accuracy without any usefulness. It isn't hard to find examples even more accurate than Randall's:

* A useless test for AIDS giving always negative results would have an accuracy about 99.95% when applied to a random human, and even more if used in countries with low prevalence of AIDS.
* A web saying "You are not the cartoonist Randall Munroe" would be right for 99.9999999857% of humans.

https://isitchristmas.com/ is a website that looks similar to the comic, with a '''No''' printed if it is not Christmas, and a '''Yes''' if it is Christmas. This website does a check on the computer's current date, and updates accordingly if it is indeed Christmas. Randall's comic doesn't do any of this, but as stated, is still correct most of the time. In addition, isitchristmas.com gives the answer in the language of your region (i.e. a visitor from Canada will give the answer in English and French to account for Canada's bilingularity); the strip only gives a fixed answer in English.

The title text is a "proof" that his service works. He claims to have tested this on 30 different days and confirmed that NO is the correct result. Any date except Christmas would result in a correct result.

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon.}}

:NO*
:<nowiki />*99.73% accurate

:[Caption below the panel:]
:xkcd.com presents a new "Is It Christmas" service to compete with isitchristmas.com

{{comic discussion}}
[[Category:Christmas]]

Talk:809: Los Alamos

2019-09-04T23:54:42Z

172.69.33.197: just conversational

How does trigonometry come into it?

[[User:Weatherlawyer| I used Google News BEFORE it was clickbait]] ([[User talk:Weatherlawyer|talk]]) 00:40, 26 January 2015 (UTC)

I think the joke of the title text lies in the word "spoiler alert".--[[Special:Contributions/199.27.128.169|199.27.128.169]] 02:32, 6 March 2015 (UTC)

Removed the following sentence from the explanation. ''Also, Steve says that he is 99% sure that it is "SOH CAH TOA, or COH SAH TOA," he is asking a question that doesn't work, since you can't be 99% sure that it is SOH CAH TOH or COH SAH TOA.''
It seems to stem from the explainer not understanding the comic. The "Although I'm 99% sure" is not a part of the question that follows, although it is part of the same sentence. Dashes are used to insert one sentence into another--like this--without changing the original sentence's meaning.
Steve's comment could be rephrased as "I have a question, although I'm 99% certain that I know the answer. Is it SOH CAH TOA, or COH SAH TOA? [[Special:Contributions/173.245.48.97|173.245.48.97]] 08:29, 28 May 2015 (UTC)

The comic also might be referencing a legend about how Trinity scientists came to Oppenheimer with their concern that the bomb might explode the world. He told them to run the math and if probability of destruction was under 1% they should still do the test (it was.) The comic implies then that the 1% probability has nothing to do with physics and is simply based on Steve's certainty about what Sine is.[[Special:Contributions/141.101.88.224|141.101.88.224]] 12:57, 1 June 2015 (UTC)

I feel that the comment is both about Steve being "99% sure" of the SOHCAHTOA, and the test being "99% sure" of not destroying the world, since Steve seems to be a mathematician behind the explosion size and effects of "The Gadget". [[User:Drcrazy102|Drcrazy102]] ([[User talk:Drcrazy102|talk]]) 00:09, 3 June 2015 (UTC)

I'd say that destroying the world is more of a 'make us as god' action than just making a big bomb. [[User:Danshoham|Mountain Hikes]] ([[User talk:Danshoham|talk]]) 23:10, 1 January 2016 (UTC)

This comic really made me think that "soh cah toa" is a bad mnemonic, since "coh sah toa" sounds just as natural and is a mistake. [[Special:Contributions/172.68.26.221|172.68.26.221]] 13:22, 14 April 2017 (UTC)

I always think "Soccer toe," but needing a mnemonic to remember another mnemonic to remember something is weird. --[[Special:Contributions/172.69.33.197|172.69.33.197]] 23:54, 4 September 2019 (UTC)

I always used an individual mnemonic for each function, so cosine is rendered 'cos-adj-hyp'; sine as 'sin-opp-hyp'; and tangent as 'tan-opp-adj'. I haven't done any trigonometry for about 30 years, and nor have I checked the mnemonics are correct, so if they are, they've worked pretty well.

312: With Apologies to Robert Frost

2019-09-03T02:18:32Z

172.69.33.197: /* Grammar fix */

{{comic
| number = 312
| date = September 5, 2007
| title = With Apologies to Robert Frost
| image = with apologies to robert frost.png
| titletext = Some say the world will end in fire; some say in segfaults.
}}

==Explanation==
This comic presents a poem about a god's dilemma of whether to create the world using {{w|Perl}} or {{w|Lisp (programming language)|Lisp}}, two popular computer programming languages. The god has chosen to write it in Perl, but since then appears to lament the choice, apparently expressing that if given the chance to write the world's code again, they would use Lisp instead.

The implication is that a universe created by Lisp would look better under close examination, the 'founding myth' referred to in the poem. Instead of an incomprehensible big bang, inflation, dark matter, and dark energy, the elegance of Lisp may have led to more elegantly framed laws of nature.

The grammar of Lisp as a language requires the programmer to use a multitude of parentheses and, in many cases, it can be difficult to determine whether all of the parentheses have been properly matched up to one another. The last two lines of the poem refer to the plentiful parentheses in Lisp, and the image at the bottom of the panel shows a close-parenthesis at the supposed end of the Universe.

A segmentation fault, also commonly called a segfault, is an error that occurs when a computer program attempts to access computer memory to which it should not have access. This is a fatal error that will cause the program to stop executing.

This comic deals with similar subject matter to [[224: Lisp]], in which one of "the gods" claims that although the Universe may appear to have been written in Lisp, it was actually written mostly using Perl.

The poem itself and the title text are a parody of "[http://www.poemhunter.com/poem/fire-and-ice/ Fire and Ice]," written by the American poet {{w|Robert Frost}} and first published in 1920. In this poem, the speaker discusses his stance in the debate on whether the world will be destroyed in fire or in ice. "A God's Lament" has a rhyme scheme that is nearly identical to that of Frost's poem. However, it differs in that "Lisp" does not rhyme with "men," "again," and "paren," while the corresponding four lines in Frost's poem do rhyme. (That said, "Lisp" does have a near-rhyme in "myth" and "with", especially if you say "Lisp" with a lisp.)

==Transcript==
{{incomplete transcript|Do NOT delete this tag too soon. needs to talk about the drawing in the back.}}
:A God's Lament
:Some said the world should be in Perl;
:Some said in Lisp.
:Now, having given both a whirl,
:I held with those who favored Perl.
:But I fear we passed to men
:A disappointing founding myth,
:And should we write it all again,
:I'd end it with
:A close-paren.

:[A multitude of planets, black holes, etc. followed by:] )

{{comic discussion}}
[[Category:Programming]]

2126: Google Trends Maps

2019-03-21T15:23:25Z

172.69.33.197:

{{comic
| number = 2126
| date = March 20, 2019
| title = Google Trends Maps
| image = google_trends_maps.png
| titletext = It's early 2020. The entire country is gripped with Marco Rubio fever except for Alaska, which is freaking out. You're frantically studying up on etiquette and/or sexting.
}}

==Explanation==
{{incomplete|Created by MARCO RUBIO. Each map needs to be individually explained. Do NOT delete this tag too soon.}}
[https://trends.google.com/ Google Trends] is a website for visualizing Google search activity by date and region. Used properly, it can give a picture of what topics people are interested in (as evidenced by what they search for) at particular times and in different places. Used improperly, it can simply [[1845:_State Word Map|amplify random noise]].

[[Randall]] has created several Google Trends maps of search activity in the US. Each map colors in states according to which of two (or more) search queries was more popular. As noted at the top of the comic, all of these based on real queries (though not reflecting the same time period across all maps). However, none of them seem to show any especially ''useful'' comparisons. States in gray did not return enough data for Google Trends to consider it significant.

* "Frostbite" vs "heat stroke": This is probably the most sensible comparison of the lot, showing which of these two risks of exposure people search up more often. However, the results are fairly obvious: in the colder northern and eastern states, "frostbite" is the more common search, while across the south and west, it's "heat stroke".
* "Best church" vs "best strip club": This map would seem to indicate people in Nevada (and only in Nevada) are more interested in strip clubs than religion. This may have something to do with the fact that Las Vegas is in Nevada.
* "Bigfoot" vs "Mike Pence": Apparently, everywhere except for Indiana, people in the US are more interested in a mythical hairy creature than in the current (at the time of this comic's release) Vice President of the United States. Since Mike Pence was once the governor of Indiana, this makes more sense if the time period covered precedes his nomination as Trump's running mate.
* "Etiquette" vs "{{w|sexting}}": Similar to the church/strip club example, this map contrasts search interest in polite behavior against risqué behavior.
* "Little dog" vs "big cat": The Trend map contrasts two searches for unidentified and briefly glimpsed wildlife that often snatch household pets left outside. The smallest canid in the wilds of America is the coyote, ''Canis latrans'', which are often smaller than the American wild dog, ''Canis lupus''. They are known for being scavenger/hunters and for the ululating "songs" their packs break into in the middle of the night. By contrast, "big cat" is a term for the largest members of the cat family (''Felidae''). Except for the jaguar, which is a roaring cat of the ''Panthera'' genus that inhabits Mexico and sometimes Arizona, the largest wild cat in North America is the mountain lion, ''Puma concolor''. It is also known as cougar, puma, catamount, ghost cat, over seventy other regional names, and the misnomer panther. (The cougar is ironically of the Felinae subfamily, all of which purr, and not Pantherinae, which roar. Black panthers in Africa are black-coated leopards, while black panthers in the Americas are black-coated jaguars, and both are Pantherinae. No black-coated pumas have been verified, leading zoologists to believe such sightings are misidentified.) "Little Dog" is also a Canadian television series, set in Newfoundland, which explains the larger number of searches for Little Dog in Maine, the state closest to Newfoundland.
* "Shark attack" vs "childbirth": While both of these things might be considered risky, there is not much of a relationship between them. As might be expected, the "shark attack" search is more common in most coastal states (and, for some reason, both Kentucky and Nevada).
* "Snakes" vs "ants" vs "bees" vs "alligators": These are all dangerous animals that cause occasional human fatalities (mainly from allergic reactions for ants and bees). There is no noticeable pattern in which animal is searched most often, though only Florida has alligators as the most common search of the four. Florida presumably has Alligators as the most searched item on this list as it is where the Everglades are located, a vast area of swamp and marsh that, aside from maintaining the ecosystem and the water supply of Florida, also is home to an obscene number of alligators.
* "Retirement planning" vs "bungee jumping": The implication here is that people in some states are more concerned with short-term fun rather than long-term planning.
* "Super Bowl" vs "funeral home": This is an attempt to contrast interest in a popular sports (and media) event against a rather somber topic.
* "Resume tips" vs "skateboard tricks": Another comparison between learning a "serious", goal-oriented skill (career advancement) and a "silly", fun skill (skateboarding). It is also an imperfect rhyme.
* "Donald Trump" vs "What do I do": The implication here seems to be that people in some states are more likely to ask Google "what do I do?", either in panic or in ignorance, than they are to look up the latest doings of the US President. The split shown is not too different to the actual split between states voting for Trump and for his opponent, Hillary Clinton.
* "Existential crisis" vs "Marco Rubio": Senator Marco Rubio was a candidate for the Republican presidential nomination in 2016. Everywhere but Alaska, people were more likely to look up his name than to search for "existential crisis".

The title text uses two of these maps to paint a picture of the year 2020 (implying that these search patterns are both meaningful and likely to continue into the future). In this scenario, most of the country continues to read about Marco Rubio (except for Alaskans, still searching for help with their existential crises), and individuals are trying to learn about etiquette, sexting, or both, depending on their location.

==Transcript==
{{incomplete transcript|Add the colored states. Do NOT delete this tag too soon.}}

:The least informative
:'''Google Trends Maps'''
:I've created over the years

:(All are real but not all cover the same date range)

:[12 maps of the United States are shown with the states colored. There are labels for the colors.]

:[Map 1]
:[Blue:] Frostbite
:[Red:] Heat stroke
:[Alabama, Arizona, Arkansas, California, Florida, Georgia, Hawaii, Idaho, Louisiana, Mississippi, Nevada, New Mexico, Oklahoma, Oregon, South Carolina, Tennessee, Texas, Utah, and Washington are red. All other states are blue.]

:[Map 2]
:[Blue:] Best church
:[Red:] Best strip club
:[Nevada is red. Alaska, North Dakota, and Wyoming are gray. All other states are blue.]

:[Map 3]
:[Blue:] Bigfoot
:[Red:] Mike Pence
:[Indiana is red. All other states are blue.]

:[Map 4]
:[Blue:] Etiquette
:[Red:] Sexting
:[Alabama, Alaska, Arkansas, Delaware, Hawaii, Iowa, Kentucky, Louisiana, Michigan, Mississippi, Missouri, Nebraska, Nevada, New Jersey, New Mexico, North Dakota, Ohio, South Dakota, Tennessee, Vermont, and West Virginia are red. All other states are blue.]

:[Map 5]
:[Blue:] Little dog
:[Red:] Big cat
:[Arizona, Arkansas, California, Colorado, Idaho, Iowa, Maine, Mississippi, Nebraska, Nevada, New Jersey, New Mexico, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, and Wyoming are blue. All other states are red.]

:[Map 6]
:[Blue:] Shark attack
:[Red:] Childbirth
:[California, Connecticut, Delaware, Florida, Georgia, Kentucky, Louisiana, Maine, Massachusetts, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Oregon, Pennsylvania, Rhode Island, South Carolina, Texas, Virginia, and West Virginia are blue. All other states are red.]

:[Map 7]
:[Blue:] Snakes
:[Red:] Ants
:[Yellow:] Bees
:[Green:] Alligators
:[Florida is green. Iowa, Maine, Massachusetts, Minnesota, Montana, Nevada, New Jersey, New Mexico, Oregon, Pennsylvania, and Wisconsin are red. Alaska, Arizona, California, Connecticut, Hawaii, Illinois, Indiana, Michigan, New Hampshire, New York, North Dakota, Ohio, Rhode Island, Utah, Vermont, Washington, and Wyoming are yellow. All other states are blue.]

:[Map 8]
:[Blue:] Retirement planning
:[Red:] Bungee jumping
:[Alaska, Delaware, Hawaii, Idaho, Mississippi, Montana, New Mexico, North Dakota, South Dakota, Vermont, West Virginia, and Wyoming are gray. Indiana, Iowa, Kansas, Maine, Maryland, Minnesota, Missouri, Nebraska, New Hampshire, New York, North Carolina, Ohio, Virginia, and Wisconsin are blue. All other states are red.]

:[Map 9]
:[Blue:] Super Bowl
:[Red:] Funeral home
:[Alaska, Arizona, California, Colorado, Connecticut, Florida, Hawaii, Idaho, Nevada, New Jersey, New York, Oregon, Pennsylvania, Texas, Utah, and Washington are blue. All other states are red.]

:[Map 10]
:[Blue:] Resume tips
:[Red:] Skateboard tricks
:[Arizona is red. Alaska, Hawaii, Idaho, Maine, Mississippi, Montana, New Hampshire, New Mexico, North Dakota, South Dakota, Vermont, West Virginia, and Wyoming are gray. All other states are blue.]

:[Map 11]
:[Blue:] Donald Trump
:[Red:] What do I do
:[California, Connecticut, Delaware, Florida, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Oregon, Rhode Island, Vermont, Virginia, Washington, and Wisconsin are blue. All other states are red.]

:[Map 12]
:[Blue:] Existential crisis
:[Red:] Marco Rubio
:[Alaska is blue. All other states are red.]

{{comic discussion}}

[[Category:Comics with color]]
[[Category:Maps]]

427: Bad Timing

2017-12-05T06:51:53Z

172.69.33.197: /* Explanation */

{{comic
| number = 427
| date = May 23, 2008
| title = Bad Timing
| image = bad_timing.png
| titletext = Protip: Even without the red spiders, never have that conversation halfway through a balloon ride.
}}

==Explanation==
[[Cueball]] breaks up with [[Megan]] in the middle of a {{w|hot air balloon}} ride. Then {{w|Non sequitur (literary device)|the red spiders attack}}.

The red spiders are among the earliest xkcd [[characters]], first appearing in [[8: Red spiders]].

As the protip in the title text states, a break-up conversation while you are stranded in an inaccessible location is very poor manners. Also, the suggestion may be interpreted that breaking up in a hot air balloon is a very dangerous way to do it; the reaction may result in one or both parties falling out of the basket, or at least make the remainder of the flight very awkward.

This was the first comic to give a ''protip'' in the title text, but several have followed as can be seen in the [[:Category:Protip|protip category]].

==Transcript==
:[Cueball and Megan, flying in a hot air balloon.]
:Cueball: I like you. I'm just not feeling the relationship.

:Cueball: I'm sorry.

:Cueball: It's just bad timing. Me with my classes, you with your work, the spiders...
:Megan: The what?

:[Red Spiders crowd onto balloon, causing it to fall.]

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Red Spiders]]
[[Category:Comics with color]]
[[Category:Romance]]
[[Category:Protip]]
[[Category:Animals]]