https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&user=172.68.34.118&feedformat=atomexplain xkcd - User contributions [en]2024-03-28T21:49:05ZUser contributionsMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=821:_Five-Minute_Comics:_Part_3&diff=177175821: Five-Minute Comics: Part 32019-07-28T14:06:01Z<p>172.68.34.118: </p>
<hr />
<div>{{comic<br />
| number = 821<br />
| date = November 19, 2010<br />
| title = Five-Minute Comics: Part 3<br />
| image = five minute comics part 3.png<br />
| titletext = Resulting in The Little Rock 9x + C.<br />
}}<br />
<br />
==Explanation==<br />
This is the third of three "five-minute comics" Randall posted during a week in November 2010. The introduction to the comic explains everything you need to know about the circumstances behind it. <br />
<br />
Randall obviously made more than three of these five minutes comics, and one of them was published later, for a short period of time by a mistake, but an android xkcd browser picked it up while it was on-line and saved it. Since then it has been added to explain xkcd. So here is a complete list of all four comics in the entire [[:Category:Five-minute comics|Five-minute comics]] series:<br />
*[[819: Five-Minute Comics: Part 1]]<br />
*[[820: Five-Minute Comics: Part 2]]<br />
*[[821: Five-Minute Comics: Part 3]]<br />
*[[Five-Minute Comics: Part 4]]<br />
<br />
Here is a list with explanations for each of the small comics:<br />
*1. {{w|Pearl Harbor}} is a US Navy base that was {{w|Attack on Pearl Harbor|attacked}} in 1941 by Japanese airplanes, which prompted the US to join World War II. The attacks were made on ''December'' 7, 1941, not November 7. Thus, Randall is correct in depicting a Navy base going about its usual business.<br />
<br />
*2. {{w|Breastfeeding in public}} is a touchy subject in parts of the world. In the US, it is considered by some to be inconsiderate to others who would prefer not to see such a display. Of course, women breastfeeding in public are generally feeding their infants, not other adults. The situation presented in the comic is an absurd exaggeration of the debate.<br />
<br />
*3. "s" is the command in {{w|sed}} to perform a pattern search-and-replace; the syntax has also been adopted by other text-processing utilities, including {{w|Perl}} (a favorite subject of xkcd), and has entered into the geek lexicon as something that could appear in general conversation. The specific command "s/I think that/I saw a study once that said/g" means "Find all occurrences of the phrase 'I think that', and replace it with the phrase 'I saw a study once that said'." This will, indeed, improve the persuasiveness of an article, as the existence of scientific evidence will make people more likely to believe what's said, while most people won't even think to actually look up the study in question.<br />
<br />
*4. Arson is the crime of intentionally setting fire to a structure. {{w|Billy Joel}} will no doubt claim {{w|We Didn't Start the Fire|he didn't start the fire}}. And it turned out that they believed him. This was mentioned in the title text of [[1794: Fire]], which displays another similarly folded newspaper front page, with only the headline readable. The picture shown the fire Billy was arrested for, but he was only detained briefly. The song is also mentioned in [[1775: Things You Learn]].<br />
<br />
*5. Coca-Cola is a fizzy cola-flavored soft drink, commonly abbreviated as "coke." {{w|Pop Rocks}} are a candy that contain tiny bubbles of gas, so that as the sugary candy dissolves on your tongue, it creates a popping sensation. For a long time, it was claimed that drinking the two together would cause one's stomach to explode; this was finally put to rest as some people (the Mythbusters in particular) started actually trying it, and discovered that it's merely painful, not lethal.<br />
:Here, it's combined with elements of other common scary urban legends (phones ringing and creepy laughter) to form something bizarre.<br />
<br />
*6. After ''{{w|Brown v. Board of Education}}'' ruled that schools could not segregate based on race, nine African American students from Little Rock, Arkansas enrolled in the previously-segregated Little Rock Central High School. The school board could not officially deny them attendance, but members of the community (and, after Arkansas governor Orval Faubus intervened, the Arkansas National Guard) formed a blockade to physically prevent them from entering the school building. The governor claimed this was within his power even after ''Brown v. Board'', because the students were enrolled without issue, they were just physically blocked from entering the school building. After determining that the right to enroll in a school does, implicitly, include the right to actually attend classes there, president Eisenhower ordered the 101st Airborne Division to accompany the students and force the National Guard to stand down, thus integrating the school. This incident became known as the {{w|Little Rock Nine}}.<br />
:However, {{w|Integral|integration}} also has a meaning in mathematics. This is indicated in the comic with the soldiers lifting up a giant integral sign to place beside the school, in order to (mathematically) integrate it. Normally, an integral only makes sense on functions; however, since this is the Little Rock ''Nine'', if we take the integral of the constant function ''f''(''x'') = 9, we do, in fact, get 9''x'' + ''C'', as stated in the title text.<br />
<br />
*7. Cell phones with advanced computing capabilities, typically at least requiring fully-featured Internet browsing, multimedia capabilities, and the ability to run software applications, are called "smartphones." Most cell phones also have a "vibrate" function that allows someone in a public situation to receive calls without alerting others; the phone will discreetly vibrate rather than activate a ringtone, thus privately notifying the owner that a call is incoming. A semi-common problem with this feature is that a vibrating phone on a table that has a slight slope will slowly - or, if the slope is bad enough, rather quickly - slide down the slope, possibly falling off the table and breaking. If our smartphones ever decided to kill us, this would possibly be their only method of attack.<br />
**Randall later covered this in his [[what if?]] blog. [http://what-if.xkcd.com/5/]<br />
<br />
*8. The Three Little Pigs is a children's fairy tale about three pigs who build their houses out of, respectively, straw, sticks, and bricks. A wolf comes along and eats the pigs living in the straw and stick houses, but he can't knock down the brick house, because his only method for breaking them down is to blow on them until the material falls to pieces. (In some variants, the foolish pigs seek refuge in the brick house for a happier ending.)<br />
:The 119 Little Pigs seems to be a variant where the pigs build their houses out of the 118 {{w|chemical elements}} (and bricks, presumably). The 38th little pig builds his house out of {{w|strontium}}, which is, of course, the 38th element on the Periodic Table. One wonders what happened to the pigs who are stuck making their houses out of elements that are gaseous or liquid at room temperature, or those whose houses would react with the air and/or undergo nuclear decay.<br />
:In his book [[what if?]]?, in the first comic, it shows the 92th little pig, who built his house out of depleted Uranium, The wolf responded, "Dude". [https://store.xkcd.com/pages/if-you-re-looking-for-the-what-if-book/] <br />
:Although given the water content in exhaled breath, it's {{w|Alkali metal#Reaction with water (alkali metal hydroxides)|easy to see}} how the wolf would huff, puff, and blow down the houses made of {{w|lithium}}, {{w|sodium}}, {{w|potassium}}, {{w|rubidium}}, {{w|caesium}}, and {{w|francium}}. Though making a houses out of {{w|hydrogen}}, {{w|helium}}, {{w|nitrogen}}, {{w|oxygen}}, {{w|fluorine}}, {{w|neon}}, {{w|chlorine}} and {{w|krypton}} would all be very difficult as they are gases at room temperature. Also, there would be issues such as death from the toxicity of the elements, e.g. fluorine would kill the pig and wolf. The piggies may have difficulty collecting enough metal, as they would have trouble collecting enough {{w|technetium}} (43), which only occurs in minute traces, and {{w|astatine}}, of which approximately 1 ounce exists on earth. <br />
:It could be a coincidence, or possibly Randall's intent, that the wolf asks "What is this shit?" while referring to strontium while stront is a Dutch word for shit.<br />
This could also be a reference to a comic from within Randall's ''What If.''<br />
<br />
*9. "Fastest gun in the West" is a boast commonly made in Western movies, where it is used to mean that a person is the fastest at drawing his gun in a duel (or, alternatively, can fire his gun the fastest). It doesn't actually describe the gun itself, and certainly doesn't describe how fast the gun can gallop across the land.<br />
<br />
*10. "It's what separates the ''men'' from the ''boys''" is a phrase used to describe "macho" activities that, apparently, only "real men" will participate/do well in; all the other men haven't grown up yet, and are thus "boys." {{w|Centrifuge}}s are used to rapidly separate a material from the liquid it's suspended in; this is either a pun on the word "separate", or an attempt by Randall to make the occupation of lab technician seem macho.<br />
**In the film ''{{W|Moonraker_(film)|Moonraker}}'', {{W|James Bond}} was almost killed in a centrifuge used as a g-force training vehicle for pilots/astronauts - but he survived - and he for sure is a real man... See also [[123: Centrifugal Force]].<br />
<br />
*11. Narnia is the mythical land in ''{{w|The Chronicles of Narnia}}''. In the books, time passes differently in Narnia, such that one can spend many years in Narnia and come out to find that almost no time at all has passed on Earth; conversely, during a short trip back to Earth, hundreds of years could pass in Narnia. {{w|Lucy Pevensie|Lucy}} is taking advantage of this by putting a computer in Narnia to perform extremely fast computation. {{w|Folding@home}} and {{w|SETI@home}} are distributed computing projects that aim to solve extremely large computational problems by pooling together computer resources of thousands of home computers who volunteer for the project; Folding@home looks at how proteins are folded, which has applications in medical science, and SETI@home analyzes EM waves from space, looking for signs extraterrestrial intelligent life amongst the cosmic background noise. Running through all of that data in a few hours would be quite an accomplishment indeed, given that, as Peter points out, the idea has many problems Lucy has evidently overcome:<br />
**The book was written in 1957 and it occurs even earlier than that, long predating personal computers, so Lucy shouldn't even have one.<br />
**Even if it occurs in an alternate universe where the PC was invented before 1957, the storage that would be needed to store the entire Folding@home and SETI@home databases would be far beyond her means, since the characters in the book are evacuees who don't have any money.<br />
**Even if she somehow pulled that much storage space together, the time needed for one computer to run through those databases is on the order of millennia. A computer would not continuously run for that long without careful treatment, which Narnia is not equipped for.<br />
**Even if we handwave around that issue (''"Aslan, use your power to keep all dust away from this computer for the next ten thousand years, please"''), the wall socket powering the computer is on the Earth side. Mains power outlets in the UK provide alternating current with an amplitude of 230 volts and a frequency of 50 hertz. The 50&nbsp;Hz part is what's important here: all devices designed to work with UK mains power expect a 50&nbsp;Hz sine wave. The time difference between Earth and Narnia would substantially elongate the sine wave in a method similar to the Doppler effect, which would probably prevent the computer from functioning at all. The frequency issue can be avoided by converting the alternating current to direct current on earth and passing the direct current to Narnia. However, to have a usable amperage (coulombs per second) on Narnia, the amperage (coulombs per second) on earth would have to be absurdly high, requiring wires much larger than shown. Also, the electricity costs would be too high.<br />
**The time differential doesn't occur while people are entering/exiting Narnia (though they do occur while the wardrobe's open) or the Pevensie children would have had had some difficulty surviving the transition. Since the cables of the computer are crossing between the worlds, it seems unlikely that the time differential is even active yet.<br />
:See also: [[1786: Trash]]<br />
<br />
*12. ''{{w|The Honeymooners}}'' is a classic American sitcom. The show stars Ralph and Alice Kramden, and Ralph frequently makes empty threats of the form "One of these days, Alice...," followed by a combination of onomatopoeia. For example: "One of these days, Alice... BANG! ZOOM! Straight to the moon!" (Alice inevitably replies "Ahhh, shut up.")<br />
:Here, Randall takes the pattern to a ridiculous and not-at-all threatening place.<br />
<br />
==Transcript==<br />
:Because of a family illness, instead of regular comics, this week I'll be sharing some strips that I drew as part of a game I played with friends. Each comic had to be written and drawn in five minutes.<br />
<br />
:--Randall<br />
<br />
:;Comic #1<br />
:Pearl Harbor. November 7th, 1941.<br />
:[There is a beach, with some ships floating in a crescent shaped harbor.]<br />
<br />
:[The same bay, again.]<br />
<br />
:[The boats continue to move about the harbor.]<br />
<br />
:[The boats do their thing. A title explains.]<br />
:(We're going to be here a while, since the attack wasn't until December.)<br />
<br />
:;Comic #2<br />
:[Cueball is sitting on a bus, Megan in front of him.]<br />
:I know it's natural and all, but I really wish women on the bus wouldn't try to breastfeed me.<br />
:Woman: C'mon, have some milk. Right here.<br />
:Me: I'm ''reading''.<br />
<br />
:;Comic #3<br />
:s/I think that/I saw a study once that said that/g<br />
:Instant persuasiveness multiplier!<br />
<br />
:;Comic #4<br />
:[A newspaper front page. Billy Joel is between two policemen.]<br />
:Times<br />
:Billy Joel Arrested for Arson<br />
<br />
:;Comic #5<br />
:[One person has a cord leaving their mouth, the other is holding a handset on the end of it to their ear.]<br />
:Handset: Hee hee hee... *giggle*<br />
:I hear that if you drink coke and eat pop rocks, you vomit up a corded telephone handset on which you hear creepy little girls giggling.<br />
<br />
:;Comic #6<br />
:[Three soldiers are holding a large integral sign, while a fourth points a gun at the Little Rock High School.]<br />
:1957: Eisenhower orders the military to integrate Little Rock High School.<br />
<br />
:;Comic #7<br />
:[A smartphone is vibrating across a table, towards a person.]<br />
:The smartphones got ''too'' smart... and developed a taste... for BLOOD!<br />
:Fortunately, the only way they could move was by turning on their vibrate while on a sloped table.<br />
<br />
:;Comic #8<br />
:[Cueball is reading to his child.]<br />
:Cueball: And the wolf went to see the 38th little pig, who had built his house out of strontium.<br />
:Cueball: And the wolf was all, "Ok, what is ''with'' this shit?"<br />
:The 119 Little Pigs<br />
<br />
:;Comic #9<br />
:[Cueball is holding up a gun.]<br />
:Cueball: Fastest gun in the west!<br />
<br />
:[The gun is galloping across the desert.]<br />
:''gallop gallop''<br />
<br />
:[There is a podium, with a gun in each position.]<br />
:Winner!<br />
<br />
:;Comic #10<br />
:[A picture of a centrifuge dominates the panel.]<br />
:Centrifuges: They're what separate the men from the boys.<br />
<br />
:;Comic #11<br />
:[A computer monitor is plugged in, and cables run into a wardrobe.]<br />
:Lucy: Time passes differently in Narnia, so by putting the CPU and storage for my machine there, I was able to run through the Folding@Home and Seti@Home databases in about an hour.<br />
:Peter: There are <u>so</u> many problems with that.<br />
<br />
:;Comic #12<br />
:[Someone is talking to Alice.]<br />
:Person: One of these days, Alice... Wham, zoom, sploosh, fwoom, splash, gurlle, wheeeee, fwoosh, aren't waterslides fun?!<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Five-minute comics| 03]]<br />
[[Category:Comics sharing name|Five-minute comics]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Substitutions]]<br />
[[Category:Chronicles of Narnia]]<br />
[[Category:Puns]]</div>172.68.34.118https://www.explainxkcd.com/wiki/index.php?title=2175:_Flag_Interpretation&diff=1766782175: Flag Interpretation2019-07-15T02:15:39Z<p>172.68.34.118: </p>
<hr />
<div>{{comic<br />
| number = 2175<br />
| date = July 12, 2019<br />
| title = Flag Interpretation<br />
| image = flag_interpretation.png<br />
| titletext = When Salvador Dalí died, it took months to get all the flagpoles sufficiently melted.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by an IMPORTANT CLONE. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}<br />
In many countries including the United States (whose flag is depicted in the comic), it is customary to lower the flag to {{w|half staff}} when important public figures die. This is normally done by raising the flag to full height, then immediately "lowering" it to half height. In the US, regulations regarding flying the flag at half staff specify the length of time for the flag to be flown at half staff, and are based on the importance of the person who has died. There are no regulations where the flag would be flown at any height other than full height or half staff, and there are no regulations where multiple flags would be flown.<br />
<br />
The definition of half-staff, or half-mast, differs between countries and does not necessarily imply flying the flag at half the height of the pole or mast. For example, in the USA the flag is usually flown at half the height of the pole, whereas UK practice is to leave space for an 'invisible flag' above the flown flag, which may mean flying the flag near the top of the pole depending on its height. These differing practices contribute to confusion and ambiguity concerning the flag height, which is exploited in the comic.<br />
<br />
Randall, as usual, makes a humorous list of fictional additional traditions.<br />
<br />
The title text is a reference to ''{{w|The Persistence of Memory}}'' and other paintings and sculptures by {{w|Salvador Dalí}} which include watches and other objects that are melting.<br />
<br />
===Table===<br />
{| border =1 width=100% cellpadding=5 class="wikitable"<br />
! Flag Position !! Randall's Interpretation || Explanation<br />
|-<br />
|Flag at half mast<br />
|Someone important died.<br />
|In the U.S., it is customary to lower the flag to half mast when somebody important died. In the flag raising ritual, the flag is supposed to be raised to full mast first and then lowered back to half mast. At the end of the day, the flag is supposed to re-raised to full mast before lowering the flag from the flagpole.<br />
|-<br />
|Flag at three-quarter mast<br />
|Someone died but we're not sure how we feel about them.<br />
|Assuming that this way of flying the flag follows the same custom as above, it can be inferred that the flag was first raised to full mast, and then lowered by only half the distance customary for honoring an important person. If the people in charge of raising the flag are not convinced of a deceased person's importance, it follows that they would give said person a half-hearted commemoration.<br />
A more literal interpretation is that a single full-mast flag can be taken to mean "nobody important died". If so, 3/4ths mast is a compromise between that and the half mast meaning; in other words, "someone half-important died".<br />
|-<br />
|Flag at base of the mast<br />
|Everyone important died.<br />
|Likewise, if the flag is lowered halfway when an important person dies, lowering it twice as far implies that multiple important people have died. No intermediate positions are shown, so we can't be sure exactly how many. However, Randall does not specify his definition of "everyone," so this scenario could possibly imply that there was an event that led to the complete cessation of life on Earth.<br />
|-<br />
|Two flags at full mast<br />
|Someone important was successfully cloned.<br />
|Following the "flag for important people" rule, two flags would mean two (cloned) important people.<br />
|-<br />
|Two flags at half mast<br />
|An important person died battling their evil clone.<br />
|The concept of evil clone (or twin) is popular in fiction; in this case, two flags at half mast would mean that both clones (good and evilly diverged), or perhaps the cloned person and their clone-gone-bad (antithetical to the presumably 'good' original), died in some battle where both failed in trying to establish themselves as the sole surviving version.<br />
|-<br />
|Flag at half mast and upside-down<br />
|Nobody has died for weeks and that seems good but statistically it's very alarming.<br />
|Since on average [https://www.worldometers.info/world-population/ someone dies every few seconds], it would indeed be extremely unlikely that no one would die for weeks in a row. Although not having anyone die seems good on the surface, it would trigger alarm about why this was happening; what mysterious force could possibly cause cessation of all deaths? And will it continue into the future, triggering an overpopulation crisis in short order?<br />
In real life, flying the US flag {{w|Distress_signal#Inverted_flags|upside down}} is widely considered a distress signal, "a signal of dire distress in instances of extreme danger to life or property", and would not be intended to indicate an important figure has died.<br />
|-<br />
|One normal-sized flag at half mast and five tiny flags at full mast<br />
|Someone diverted a trolley to save five people by killing one important person.<br />
|This is a reference to the {{w|Trolley problem}}, a well-known thought experiment in ethics: An out-of-control trolley is running toward five people who are on the tracks. If you do nothing, these five will be killed. However, you can trigger a switch that will divert the trolley onto a side track, where there is one person who would be killed. Which is the more ethical option?<br />
In this case, the important person was sacrificed, and so is commemorated by the usual custom of lowering the flag to half-mast. The small flags, which represent the non-important people, fly at full mast to indicate those people's continued survival.<br />
|-<br />
|No flag on the pole<br />
|The person who knows where the flag is stored at night died.<br />
|Presumably the flag-keeper died during the night, and nobody living knows where the flag is stored and can't seem to locate it to put it on the flagpole.<br />
|}<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[8 panels in 2 rows, 4 panels per row - each panel shows a flagpole in a different state of flying flag(s) with a caption at the bottom of the panel below the flagpole.]<br />
:[The US flag at half mast.]<br />
:Caption: Someone important died<br />
:[The same flag at three-quarter mast.]<br />
:Caption: Someone died but we're not sure how we feel about them<br />
:[The flag at the base of the mast.]<br />
:Caption: Everyone important died<br />
:[Two identical flags at full mast.]<br />
:Caption: Someone important was successfully cloned<br />
:[Two identical flags at half mast.]<br />
:Caption: An important person died battling their evil clone<br />
:[An upside-down flag at half mast.]<br />
:Caption: Nobody has died for weeks and that seems good but statistically it's very alarming.<br />
:[A normal-sized flag at half mast and five tiny flags at full mast.]<br />
:Caption: Someone diverted a trolley to save five people by killing one important person<br />
:[A flagpole with no flag.]<br />
:Caption: The person who knows where the flag is stored at night died.<br />
<br />
{{comic discussion}}</div>172.68.34.118https://www.explainxkcd.com/wiki/index.php?title=2175:_Flag_Interpretation&diff=1766772175: Flag Interpretation2019-07-15T02:12:24Z<p>172.68.34.118: </p>
<hr />
<div>{{comic<br />
| number = 2175<br />
| date = July 12, 2019<br />
| title = Flag Interpretation<br />
| image = flag_interpretation.png<br />
| titletext = When Salvador Dalí died, it took months to get all the flagpoles sufficiently melted.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by an IMPORTANT CLONE. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}<br />
In many countries including the United States (whose flag is depicted in the comic), it is customary to lower the flag to {{w|half staff}} when important public figures die. This is normally done by raising the flag to full height, then immediately "lowering" it to half height. In the US, regulations regarding flying the flag at half staff specify the length of time for the flag to be flown at half staff, and are based on the importance of the person who has died. There are no regulations where the flag would be flown at any height other than full height or half staff, and there are no regulations where multiple flags would be flown.<br />
<br />
The definition of half-staff, or half-mast, differs between countries and does not necessarily imply flying the flag at half the height of the pole or mast. For example, in the USA the flag is usually flown at half the height of the pole, whereas UK practice is to leave space for an 'invisible flag' above the flown flag, which may mean flying the flag near the top of the pole depending on its height. These differing practices contribute to confusion and ambiguity concerning the flag height, which is exploited in the comic.<br />
<br />
Randall, as usual, makes a humorous list of fictional additional traditions.<br />
<br />
Flying the US flag {{w|Distress_signal#Inverted_flags|upside down}} is widely considered a distress signal, and would not be intended to indicate an important figure has died. Since on average [https://www.worldometers.info/world-population/ someone dies every few seconds], it would indeed be extremely unlikely that no one would die for weeks in a row. Although not having anyone die seems good on the surface, it would trigger alarm about why this was happening; what mysterious force could possibly cause cessation of all deaths? And will it continue into the future, triggering an overpopulation crisis in short order?<br />
<br />
The second-to-last panel is a reference to the <br />
<br />
The title text is a reference to ''{{w|The Persistence of Memory}}'' and other paintings and sculptures by {{w|Salvador Dalí}} which include watches and other objects that are melting.<br />
<br />
===Table===<br />
{| border =1 width=100% cellpadding=5 class="wikitable"<br />
! Flag Position !! Randall's Interpretation || Explanation<br />
|-<br />
|Flag at half mast<br />
|Someone important died.<br />
|In the U.S., it is customary to lower the flag to half mast when somebody important died. In the flag raising ritual, the flag is supposed to be raised to full mast first and then lowered back to half mast. At the end of the day, the flag is supposed to re-raised to full mast before lowering the flag from the flagpole.<br />
|-<br />
|Flag at three-quarter mast<br />
|Someone died but we're not sure how we feel about them.<br />
|Assuming that this way of flying the flag follows the same custom as above, it can be inferred that the flag was first raised to full mast, and then lowered by only half the distance customary for honoring an important person. If the people in charge of raising the flag are not convinced of a deceased person's importance, it follows that they would give said person a half-hearted commemoration.<br />
A more literal interpretation is that a single full-mast flag can be taken to mean "nobody important died". If so, 3/4ths mast is a compromise between that and the half mast meaning; in other words, "someone half-important died".<br />
|-<br />
|Flag at base of the mast<br />
|Everyone important died.<br />
|Likewise, if the flag is lowered halfway when an important person dies, lowering it twice as far implies that multiple important people have died. No intermediate positions are shown, so we can't be sure exactly how many. However, Randall does not specify his definition of "everyone," so this scenario could possibly imply that there was an event that led to the complete cessation of life on Earth.<br />
|-<br />
|Two flags at full mast<br />
|Someone important was successfully cloned.<br />
|Following the "flag for important people" rule, two flags would mean two (cloned) important people.<br />
|-<br />
|Two flags at half mast<br />
|An important person died battling their evil clone.<br />
|The concept of evil clone (or twin) is popular in fiction; in this case, two flags at half mast would mean that both clones (good and evilly diverged), or perhaps the cloned person and their clone-gone-bad (antithetical to the presumably 'good' original), died in some battle where both failed in trying to establish themselves as the sole surviving version.<br />
|-<br />
|Flag at half mast and upside-down<br />
|Nobody has died for weeks and that seems good but statistically it's very alarming.<br />
|The fact that nobody died for weeks is an impressive statistic since many deaths occur every day, so it would indicate a big change in society for this happen. Flying a flag upside-down is {{w|Flag_desecration#Flying_a_U.S._flag_upside_down|often used as}} "a signal of dire distress in instances of extreme danger to life or property".<br />
|-<br />
|One normal-sized flag at half mast and five tiny flags at full mast<br />
|Someone diverted a trolley to save five people by killing one important person.<br />
|This is a reference to the {{w|Trolley problem}}, a well-known thought experiment in ethics: An out-of-control trolley is running toward five people who are on the tracks. If you do nothing, these five will be killed. However, you can trigger a switch that will divert the trolley onto a side track, where there is one person who would be killed. Which is the more ethical option?<br />
In this case, the important person was sacrificed, and so is commemorated by the usual custom of lowering the flag to half-mast. The small flags, which represent the non-important people, fly at full mast to indicate those people's continued survival.<br />
|-<br />
|No flag on the pole<br />
|The person who knows where the flag is stored at night died.<br />
|Presumably the flag-keeper died during the night, and nobody living knows where the flag is stored and can't seem to locate it to put it on the flagpole.<br />
|}<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[8 panels in 2 rows, 4 panels per row - each panel shows a flagpole in a different state of flying flag(s) with a caption at the bottom of the panel below the flagpole.]<br />
:[The US flag at half mast.]<br />
:Caption: Someone important died<br />
:[The same flag at three-quarter mast.]<br />
:Caption: Someone died but we're not sure how we feel about them<br />
:[The flag at the base of the mast.]<br />
:Caption: Everyone important died<br />
:[Two identical flags at full mast.]<br />
:Caption: Someone important was successfully cloned<br />
:[Two identical flags at half mast.]<br />
:Caption: An important person died battling their evil clone<br />
:[An upside-down flag at half mast.]<br />
:Caption: Nobody has died for weeks and that seems good but statistically it's very alarming.<br />
:[A normal-sized flag at half mast and five tiny flags at full mast.]<br />
:Caption: Someone diverted a trolley to save five people by killing one important person<br />
:[A flagpole with no flag.]<br />
:Caption: The person who knows where the flag is stored at night died.<br />
<br />
{{comic discussion}}</div>172.68.34.118https://www.explainxkcd.com/wiki/index.php?title=2175:_Flag_Interpretation&diff=1766762175: Flag Interpretation2019-07-15T02:07:40Z<p>172.68.34.118: /* Table */</p>
<hr />
<div>{{comic<br />
| number = 2175<br />
| date = July 12, 2019<br />
| title = Flag Interpretation<br />
| image = flag_interpretation.png<br />
| titletext = When Salvador Dalí died, it took months to get all the flagpoles sufficiently melted.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by an IMPORTANT CLONE. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}<br />
In many countries including the United States (whose flag is depicted in the comic), it is customary to lower the flag to {{w|half staff}} when important public figures die. This is normally done by raising the flag to full height, then immediately "lowering" it to half height. In the US, regulations regarding flying the flag at half staff specify the length of time for the flag to be flown at half staff, and are based on the importance of the person who has died. There are no regulations where the flag would be flown at any height other than full height or half staff, and there are no regulations where multiple flags would be flown.<br />
<br />
The definition of half-staff, or half-mast, differs between countries and does not necessarily imply flying the flag at half the height of the pole or mast. For example, in the USA the flag is usually flown at half the height of the pole, whereas UK practice is to leave space for an 'invisible flag' above the flown flag, which may mean flying the flag near the top of the pole depending on its height. These differing practices contribute to confusion and ambiguity concerning the flag height, which is exploited in the comic.<br />
<br />
Randall, as usual, makes a humorous list of fictional additional traditions.<br />
<br />
Flying the US flag {{w|Distress_signal#Inverted_flags|upside down}} is widely considered a distress signal, and would not be intended to indicate an important figure has died. Since on average [https://www.worldometers.info/world-population/ someone dies every few seconds], it would indeed be extremely unlikely that no one would die for weeks in a row. Although not having anyone die seems good on the surface, it would trigger alarm about why this was happening; what mysterious force could possibly cause cessation of all deaths? And will it continue into the future, triggering an overpopulation crisis in short order?<br />
<br />
The second-to-last panel is a reference to the {{w|Trolley problem}}, a well-known thought experiment in ethics: An out-of-control trolley is running toward five people who are on the tracks. If you do nothing, these five will be killed. However, you can trigger a switch that will divert the trolley onto a side track, where there is one person who would be killed. Which is the more ethical option?<br />
<br />
The title text is a reference to ''{{w|The Persistence of Memory}}'' and other paintings and sculptures by {{w|Salvador Dalí}} which include watches and other objects that are melting.<br />
<br />
===Table===<br />
{| border =1 width=100% cellpadding=5 class="wikitable"<br />
! Flag Position !! Randall's Interpretation || Explanation<br />
|-<br />
|Flag at half mast<br />
|Someone important died.<br />
|In the U.S., it is customary to lower the flag to half mast when somebody important died. In the flag raising ritual, the flag is supposed to be raised to full mast first and then lowered back to half mast. At the end of the day, the flag is supposed to re-raised to full mast before lowering the flag from the flagpole.<br />
|-<br />
|Flag at three-quarter mast<br />
|Someone died but we're not sure how we feel about them.<br />
|Assuming that this way of flying the flag follows the same custom as above, it can be inferred that the flag was first raised to full mast, and then lowered by only half the distance customary for honoring an important person. If the people in charge of raising the flag are not convinced of a deceased person's importance, it follows that they would give said person a half-hearted commemoration.<br />
A more literal interpretation is that a single full-mast flag can be taken to mean "nobody important died". If so, 3/4ths mast is a compromise between that and the half mast meaning; in other words, "someone half-important died".<br />
|-<br />
|Flag at base of the mast<br />
|Everyone important died.<br />
|Likewise, if the flag is lowered halfway when an important person dies, lowering it twice as far implies that multiple important people have died. No intermediate positions are shown, so we can't be sure exactly how many. However, Randall does not specify his definition of "everyone," so this scenario could possibly imply that there was an event that led to the complete cessation of life on Earth.<br />
|-<br />
|Two flags at full mast<br />
|Someone important was successfully cloned.<br />
|Following the "flag for important people" rule, two flags would mean two (cloned) important people.<br />
|-<br />
|Two flags at half mast<br />
|An important person died battling their evil clone.<br />
|The concept of evil clone (or twin) is popular in fiction; in this case, two flags at half mast would mean that both clones (good and evilly diverged), or perhaps the cloned person and their clone-gone-bad (antithetical to the presumably 'good' original), died in some battle where both failed in trying to establish themselves as the sole surviving version.<br />
|-<br />
|Flag at half mast and upside-down<br />
|Nobody has died for weeks and that seems good but statistically it's very alarming.<br />
|The fact that nobody died for weeks is an impressive statistic since many deaths occur every day, so it would indicate a big change in society for this happen. Flying a flag upside-down is {{w|Flag_desecration#Flying_a_U.S._flag_upside_down|often used as}} "a signal of dire distress in instances of extreme danger to life or property".<br />
|-<br />
|One normal-sized flag at half mast and five tiny flags at full mast<br />
|Someone diverted a trolley to save five people by killing one important person.<br />
|This is a reference to the {{w|Trolley_problem|trolley problem.}}. The small flags are for the non-important people. Since they are not important, their flags are smaller.<br />
|-<br />
|No flag on the pole<br />
|The person who knows where the flag is stored at night died.<br />
|Presumably the flag-keeper died during the night, and nobody living knows where the flag is stored and can't seem to locate it to put it on the flagpole.<br />
|}<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[8 panels in 2 rows, 4 panels per row - each panel shows a flagpole in a different state of flying flag(s) with a caption at the bottom of the panel below the flagpole.]<br />
:[The US flag at half mast.]<br />
:Caption: Someone important died<br />
:[The same flag at three-quarter mast.]<br />
:Caption: Someone died but we're not sure how we feel about them<br />
:[The flag at the base of the mast.]<br />
:Caption: Everyone important died<br />
:[Two identical flags at full mast.]<br />
:Caption: Someone important was successfully cloned<br />
:[Two identical flags at half mast.]<br />
:Caption: An important person died battling their evil clone<br />
:[An upside-down flag at half mast.]<br />
:Caption: Nobody has died for weeks and that seems good but statistically it's very alarming.<br />
:[A normal-sized flag at half mast and five tiny flags at full mast.]<br />
:Caption: Someone diverted a trolley to save five people by killing one important person<br />
:[A flagpole with no flag.]<br />
:Caption: The person who knows where the flag is stored at night died.<br />
<br />
{{comic discussion}}</div>172.68.34.118https://www.explainxkcd.com/wiki/index.php?title=Talk:2175:_Flag_Interpretation&diff=176612Talk:2175: Flag Interpretation2019-07-12T16:27:14Z<p>172.68.34.118: </p>
<hr />
<div><!--Please sign your posts with ~~~~ and don't delete this text. New comments should be added at the bottom.--><br />
Can we all just take a moment to appreciate that Randall drew each US flag by hand? He could have just copy-pasted the same one 14 times, but he didn't. [[Special:Contributions/172.68.34.118|172.68.34.118]] 16:27, 12 July 2019 (UTC)<br />
<br />
Something about a Dali-esque melting flagpole set at half-mast seems very suggestive to me...<br />
<br />
Flying the US flag upside down would be considered a distress signal by many. Should this be in the main description or a "trivia" section? [[User:Cgrimes85|Cgrimes85]] ([[User talk:Cgrimes85|talk]]) 15:51, 12 July 2019 (UTC)<br />
<br />
Half mast or half staff? In the US (which appears to be the flag shown in the comic), the popular usage is half-staff, although half-mast is more common elsewhere. [[User:Cgrimes85|Cgrimes85]] ([[User talk:Cgrimes85|talk]]) 15:56, 12 July 2019 (UTC)<br />
: Half-mast should be for naval connotations and half-staff for non-naval connotations, at least in the USA.</div>172.68.34.118https://www.explainxkcd.com/wiki/index.php?title=1714:_Volcano_Types&diff=1764111714: Volcano Types2019-07-10T17:34:49Z<p>172.68.34.118: /* Joke volcanoes */ Added an important {{Citation needed}}</p>
<hr />
<div>{{comic<br />
| number = 1714<br />
| date = August 1, 2016<br />
| title = Volcano Types<br />
| image = volcano_types.png<br />
| titletext = It's hard living somewhere with antlions, because every time you find one of their traps, you feel compelled to spend all day constructing a tiny model of Jabba's sail barge next to it.<br />
}}<br />
<br />
==Explanation==<br />
This comic presents a table of 12 different types of volcano. Split into 3 rows, the first 4 are authentic types of volcano; while the remaining 8 are parodies, one not even trying to represent a volcano but shows a real animal in its inverted trap cone.<br />
<br />
Volcanoes have featured in many xkcd comics, [[media:1608 Entire Volcano plateau zoom out_extra.png|most prominently]] in the left part of the world (the Lord of the Rings section) of [[1608: Hoverboard]]. This comic's volcano looks like it could soon turn into a Somma volcano.<br />
<br />
===Real volcanoes===<br />
*{{w|Cinder cone}}: small, steep-sided volcano formed of {{w|scoria}} and ash.<br />
*{{w|Shield volcano}}: wide, rounded volcano formed of solidified lava flow.<br />
*{{w|Stratovolcano}}: large volcano formed of layers (strata) from multiple eruptions.<br />
*{{w|Somma volcano}}: new volcanic cone in the middle of an old collapsed volcanic crater.<br />
<br />
===Joke volcanoes===<br />
*Metasomma volcano: nested layers of somma volcanos i.e. a whole set of new volcanoes (three in this situation) formed inside of old ones. "Meta" is a prefix that often denotes recursion. (Although this is a joke volcano, metasomma volcanoes do actually exist in real life, with one example being the {{w|Krakatoa}} group in Indonesia.)<br />
*{{w|Waffle cone}}: type of pastry that ice cream is served in, related to volcano cones only insofar as they are the same shape, but typically the waffle cones are turned the other way up to keep the ice cream inside{{Citation needed}}. If the tip of the waffle cone is not filled with solid chocolate or similar, then the contents may very well melt and run out the bottom like the smoke coming out at the very tip of the Waffle cone volcano.<br />
*Science fair cone: common elementary science experiment that is often used as a project for science fairs. A structure is built to resemble a model volcano and is filled with a mix of baking soda, vinegar, and sometimes food coloring. The reaction between baking soda and vinegar quickly produces a large amount of carbon dioxide, creating a foam that overflows and mimics a volcanic eruption. In this picture, there are people running away from the volcano that are much smaller than it. This is likely a reference to [[1611: Baking Soda and Vinegar]], either the scale-model people on the first volcano, or real people running from the baking soda supervolcano (in this case two [[Cueball]]-like guys and [[Megan]]).<br />
*Doot cone: This may likely be a reference to the meme of the [http://knowyourmeme.com/memes/skull-trumpet skull-trumpet] where the trumpet playing skull [https://www.reddit.com/r/OutOfTheLoop/comments/39xnk2/what_is_this_doot_thing_with_the_skeletons/cs7jdsa produces the sound Doot] as a large part of the meme. Doot is also a fart sound; a doot cone could be just ejecting farts instead of lava.<br />
**There has been some discussion about if this is likely, with someone referencing the [https://www.amazon.com/Florida-DOT-Approved-Traffic-Cone/dp/B009RUTKZA DOT cones], traffic cones approved by DOT or the {{w|Department of transportation}} in the US.<br />
**Also there have been mention of ''{{w|Dot-com}}'' coming close to ''Doot cone''. The {{w|Dot-com bubble}} could be said to burst, just like this volcano bursts/erupts.<br />
*{{w|Antlion}}: An antlion is the larva of an insect known as the lacewing, and is commonly called a doodlebug. These insects dig pits in the sand to use as traps; when a bug comes along and falls in, the sand collapses and falls on the bug, making it very difficult to escape. The antlion then eats the unsuspecting prey. Maybe a reference to {{w|Formica Leo}}, a small volcanic crater in the Reunion island named after the antlion. Also, a recurring boss villain in the video game Final Fantasy series. Also appears in the {{w|List_of_Moomin_(1990)_episodes|Moomin (1990) TV series}} as a literal black lion.<br />
*Inverse Volcano: as the name implies, a regular volcano but reversed. A real volcano consists of solid rock on the outside, magma on the inside and spewing lava from the top.<br />
*Ghost Vent: cone with ghosts coming out of it. <br />
*Pedant's Bane: the joke is that people sometimes confuse magma and lava, which are different names for the same heated liquid rock. Magma becomes lava when it emerges from a volcano. The Pedant's Bane volcano is therefore impossible by definition, but if it were possible, then a {{w|pedant}} would have met his [https://en.wiktionary.org/wiki/bane#Etymology_1 bane] (i.e. his downfall), because when he corrected someone's description of this volcano, the pedant would actually be wrong. Alternatively, the illustration itself could be Pedant's Bane because a pedant would be lured into pointing out how wrong it is. This is a direct reference to the pedant in [[1405: Meteor]].<br />
<br />
The title text refers to a famous scene in ''{{w|Star Wars: Episode VI - Return of the Jedi}}'' where {{w|Jabba the Hutt}} intends to feed {{w|Luke Skywalker}} to the {{w|Sarlacc|sarlacc}}, an underground creature that builds a huge funnel trap similar to that of an antlion. [[wikia:c:starwars:Khetanna|Jabba's distinctive sail barge]] features prominently in that scene, and when Randall comes upon an antlion he can't help himself starting to build a scale model next to the antlion's inverted cone. Given how small antlions are, this will be very difficult to do, see for instance [[878: Model Rail]].<br />
<br />
==Transcript==<br />
:[Twelve drawings in four rows of different "volcano" types, the first four real, and some not even volcanoes of any sort, real or fake. Below each panel is a caption with the name of the drawn volcano. Some of the volcanoes have labels or sound written inside the panel. Each of the volcanoes has a baseline for the ground going straight a short distance over the bottom of each panel. All 11 volcanoes lie on top of this line, but some show the inside of the volcano going further into the ground.]<br />
<br />
:[Standard cone shaped volcano, with straight sides sloping up to a triangular shape, but with the tip of the cone cut off to form the central jagged edged crater. White smoke rises straight up and then drifts to the left forming three separate clouds.]<br />
:Cinder Cone<br />
<br />
:[Flat rounded shaped volcano, as a part of a circle. There is not a real crater visible but from the center a thin plume of smoke rises up, drift drifts to the left and forms a small white cloud.]<br />
:Shield Volcano<br />
<br />
:[This is the largest volcano. The tip of this volcano is similar to the first volcano, but with more uneven slopes and a bit smaller. The tip is clearly separated from the bottom section by a thin jagged line, and below the sides of the volcano decreases their slope, so they are less steep than the tip. Black smoke rises straight up from the crater and then drifts to the left in four thin lines.]<br />
:Stratovolcano<br />
<br />
:[A wide volcano spans the entire panel, with a large central crater, with a bottom baseline far above the ground level. Just left of the middle of this crater is a standard smaller volcano cone, very similar to the shape of the tip in the previous panel. Even the smoke from this cones small crater is similar to the previous panels.]<br />
:Somma Volcano<br />
<br />
:[The central part of this volcano is the same shape as the previous panel. This could be a zoom out, revealing that the large crater, is at the center on an even larger crater, which again is at the center of a crater that spans the panel. A plume of black smoke rises from the centeral cones crater, and drifts left as five white clouds.]<br />
:Metasomma Volcano<br />
<br />
:[A perfect cone-shape, triangular and steep, with checkered ice cone waffle texture, even with a line indicating where the waffle has been a folded. It looks like a road up the volcano. Black smoke drift up from the sharp tip, no crater, and drifts left forming a small cloud separated from the rest of the smoke lines.]<br />
:Waffle Cone<br />
<br />
:[Standard cone as in the first, but zoomed in so it fills the panel from left to right. The volcano's top has been cut much further down leaving a wide crater from which lava is pouring down the sides in large rivers of different width and length. To the left one long river has almost reached the ground. Cueball is running down the left side, and Megan is running after another Cueball with his arms up on the right side. There is a label with an arrow pointing to the lava:]<br />
:Label: Baking soda and vinegar<br />
:Science Fair Cone<br />
<br />
:[Standard cone like the previous, but with more jagged sloped and crater. This volcano erupts with a large explosion with fire and smoke coming out in all directions above the crater. A large sound is written above the explosion:]<br />
:Sound. <big>'''Doooooot'''</big><br />
:Doot Cone<br />
<br />
:[This is not a volcano, but the inverse, a cone down into the ground, the ground level no above the center of the panel. The slope down into this cone hole is straight, the ground above is more jagged. At the bottom of the hole sits a small animal with six legs and an open mouth piece sticking up out of the hole. Its fat body is hidden under the ground along with its legs.]<br />
:Antlion<br />
<br />
:[Standard volcano cone like the previous volcano. It erupts and the central part shows how the erupting material comes up from below ground level (below the line at the bottom in which the cone it self stands). The erupting material is white rocks on black background. At the top several rocks is blown out of the crater top. The sides of the volcano is filled with blobs small and large, and stones rolling down the sides. There are two labels, each with two arrows. The first labels arrows points to the side of the volcano, the second labels arrows points to the erupting material inside and outside the volcano:]<br />
:First label: Lava<br />
:Second label: Solid rocks<br />
:Inverse Volcano<br />
<br />
:[Standard cone like the doot cone, with a crater that bends down in the middle. From this crater eight white ghosts with two black eyes are rising, like the smoke, drifting left. The highest ghost is just reaching the edge at the top left of the panel. The lowest ghost is still inside the crater with its wavy lower parts.]<br />
:Ghost Vent<br />
<br />
:[A standard cone like the doot cone. At the top there is lave over the outer edges, some of it running down the side. The inside of the volcano has been drawn like in the inverse volcano, so it is clear that the magma inside the volcano comes up from below ground level (below the line at the bottom in which the cone it self stands). There are two labels that contradicts the description above. The top label outside the volcano points to the lava with an arrow, and the bottom label inside the volcano points to the magma:]<br />
:Top label: Magma<br />
:Bottom label: Lava<br />
:Pedant's Bane<br />
<br />
{{comic discussion}}<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Multiple Cueballs]]<br />
[[Category:Food]] <!-- Waffle cone--><br />
[[Category:Animals]] <!-- Ant lion--><br />
[[Category:Star Wars]]<br />
[[Category:Geography]]<br />
[[Category:Pedantic]]</div>172.68.34.118https://www.explainxkcd.com/wiki/index.php?title=2117:_Differentiation_and_Integration&diff=1760712117: Differentiation and Integration2019-07-02T00:21:27Z<p>172.68.34.118: /* Explanation */</p>
<hr />
<div>{{comic<br />
| number = 2117<br />
| date = February 27, 2019<br />
| title = Differentiation and Integration<br />
| image = differentiation_and_integration.png<br />
| titletext = "Symbolic integration" is when you theatrically go through the motions of finding integrals, but the actual result you get doesn't matter because it's purely symbolic.<br />
}}<br />
<br />
==Explanation==<br />
This comic illustrates the old saying [https://mathoverflow.net/q/66377 "Differentiation is mechanics, integration is art."] It does so by providing a {{w|flowchart}} purporting to show the process of differentiation, and another for integration.<br />
<br />
{{w|Derivative|Differentiation}} and {{w|Antiderivative|Integration}} are two major components of {{w|calculus}}. As many Calculus 2 students are painfully aware, integration is much more complicated than the differentiation it undoes.<br />
<br />
However, Randall dramatically overstates this point here. After the first step of integration, Randall assumes that any integration can not be solved so simply, and then dives into a step named "????", suggesting that it is unknowable how to proceed. The rest of the flowchart is (we can assume deliberately) even harder to follow, and does not reach a conclusion. This is in contrast to the simple, straightforward flowchart for differentiation. The fact that the arrows in the bottom of the integration part leads to nowhere indicates that "Phone calls to mathematicians", "Oh no" and "Burn the evidence" are not final steps in the difficult journey. The flowchart could be extended by Randall to God-knows-where extents.<br />
<br />
It should be noted that Randall slightly undermines his point by providing four different methods, and an "etc", and a "No"-branch for attempting differentiation with no guidelines for selecting between them.<br />
<br />
===Differentiation===<br />
'''{{w|Chain rule}}'''<br />
<br />
For any <math> \frac{d}{dx}f(x)=f'(x)</math> and <math> \frac{d}{dx}g(x)=g'(x) </math>, it follows that <math> \frac{d}{dx}(f(g(x)))=f'(g(x))\cdot g'(x)</math>.<br />
<br />
'''{{w|Power Rule}}'''<br />
<br />
For any <math> f(x)=x^a </math>, it follows that <math> \frac{d}{dx}f(x)=a\cdot x^{a-1} </math>.<br />
<br />
'''{{w|Quotient rule}}'''<br />
<br />
For any <math> \frac{d}{dx}f(x)=f'(x)</math> and <math> \frac{d}{dx}g(x)=g'(x) </math>, it follows that <math> \frac{d}{dx} \frac{f(x)}{g(x)}=\frac{f'(x)\cdot g(x)-f(x)\cdot g'(x)}{(g(x))^2}</math> if <math>g(x)\ne 0</math>.<br />
<br />
'''{{w|Product rule}}'''<br />
<br />
For any <math> \frac{d}{dx}f(x)=f'(x)</math> and <math> \frac{d}{dx}g(x)=g'(x) </math>, it follows that <math> \frac{d}{dx}(f(x)\cdot g(x))=f'(x)\cdot g(x)+f(x)\cdot g'(x)</math>.<br />
<br />
===Integration===<br />
'''{{w|Integration by parts}}'''<br />
<br />
The "product rule" run backwards. Since <math>(uv)' = uv' + u'v</math>, it follows that by integrating both sides you get <math> uv = \int u dv + \int v du</math>, which is more commonly written as <math>\int u dv = uv - \int v du</math>. By finding appropriate values for functions <math>u, v</math> such that your problem is in the form <math>\int u dv</math>, your problem ''may'' be simplified. The catch is, there exists no algorithm for determining what functions they might possibly be, so this approach quickly devolves into a guessing game - this has been the topic of an earlier comic, [[1201: Integration by Parts]].<br />
<br />
'''{{w|Integration by substitution|Substitution}}'''<br />
<br />
The "chain rule" run backwards. Since <math> d(f(u)) = (df(u))du</math>, it follows that <math>f(u) = \int df(u) du</math>. By finding appropriate values for functions <math>f, u</math> such that your problem is in the form <math>\int df(u) du</math> your problem ''may'' be simplified.<br />
<br />
'''{{w|Cauchy's integral formula|Cauchy's Formula}}'''<br />
<br />
Cauchy's Integral formula is a result in complex analysis that relates the value of a contour integral in the complex plane to properties of the singularities in the interior of the contour. It is often used to compute integrals on the real line by extending the path of the integral from the real line into the complex plane to apply the formula, then proving that the integral from the parts of the contour not on the real line has value zero. <br />
<br />
'''{{w|Partial_fraction_decomposition#Application_to_symbolic_integration|Partial Fractions}}'''<br />
<br />
Partial fractions is a technique for breaking up a function that comprises one polynomial divided by another into a sum of functions comprising constants over the factors of the original denominator, which can easily be integrated into logarithms.<br />
<br />
'''Install {{w|Mathematica}}'''<br />
<br />
Mathematica is a modern technical computing system spanning most areas. One of its features is to compute mathematical functions. This step in the flowchart is to install and use Mathematica to do the integration for you. Here is a description about the [https://reference.wolfram.com/language/tutorial/IntegralsThatCanAndCannotBeDone.html intricacies of integration and how Mathematica handles those]. (It would be quicker to try [https://www.wolframalpha.com Wolfram Alpha] instead of installing Mathematica, which uses the same backend for mathematical calculations.)<br />
<br />
'''{{w|Riemann integral|Riemann Integration}}'''<br />
<br />
The Riemann integral is a definition of definite integration. <math>\sum_{i=0}^{n-1} f(t_i) \left(x_{i+1}-x_i\right).</math> Elementary textbooks on calculus sometimes present finding a definite integral as a process of approximating an area by strips of equal width and then taking the limit as the strips become narrower. Riemann integration removes the requirement that the strips have equal width, and so is a more flexible definition. However there are still many functions for which the Riemann integral doesn't converge, and consideration of these functions leads to the {{w|Lebesgue integration|Lebesgue integral}}. Riemann integration is not a method of calculus appropriate for finding the anti-derivative of an elementary function.<br />
<br />
'''{{w|Stokes' Theorem}}'''<br />
<br />
Stokes' theorem is a statement about the integration of differential forms on manifolds. <math>\int_{\partial \Omega}\omega=\int_\Omega d\omega\,.</math> It is invoked in science and engineering during control volume analysis (that is, to track the rate of change of a quantity within a control volume, it suffices to track the fluxes in and out of the control volume boundary), but is rarely used directly (and even when it is used directly, the functions that are most frequently used in science and engineering are well-behaved, like sinusoids and polynomials). <br />
<br />
'''{{w|Risch Algorithm}}'''<br />
<br />
The Risch algorithm is a notoriously complex procedure that, given a certain class of symbolic integrand, either finds a symbolic integral or proves that no elementary integral exists. (Technically it is only a semi-algorithm, and cannot produce an answer unless it can determine if a certain symbolic expression is {{w|Constant problem|equal to 0}} or not.) Many computer algebra systems have chosen to implement only the simpler Risch-Norman algorithm, which does not come with the same guarantee. A series of extensions to the Risch algorithm extend the class of allowable functions to include (at least) the error function and the logarithmic integral. A human would have to be pretty desperate to attempt this (presumably) by hand.<br />
<br />
'''{{w|Bessel function}}'''<br />
<br />
Bessel functions are the solution to the differential equation <math> x^2 \frac{dy^2}{dx^2}+x \frac{dy}{dx}+(x^2-n^2)*y=0</math>, where n is the order of Bessel function. Though they do show up in some engineering, physics, and abstract mathematics, in lower levels of calculus they are often a sign that the integration was not set up properly before someone put them into a symbolic algebra solver.<br />
<br />
'''Phone calls to mathematicians'''<br />
<br />
This step would indicate that the flowchart user, desperate from failed attempts to solve the problem, contacts some more skilled mathematicians by phone, and presumably asks them for help. The connected steps of "Oh no" and "Burn the evidence" may suggest the possibility that this interaction might not play out very well and could even get the caller in trouble.<br />
Specialists and renowned experts being bothered - not to their amusement - by strangers, often at highly inconvenient times or locations, is a common comedic trope, also previously utilized by xkcd (for example in [[163: Donald Knuth]]).<br />
<br />
'''Burn the evidence'''<br />
<br />
This phrase parodies a common trope in detective fiction, where characters burn notes, receipts, passports, etc. to maintain secrecy. This may refer to the burning of one's work to avoid the shame of being associated with such a badly failed attempt to solve the given integration problem. Alternatively, it could be an ironic hint to the fact that in order to find the integral, it may even be necessary to break the law or upset higher powers, so that the negative consequences of a persecution can only be avoided by destroying the evidence.<br />
<br />
'''{{w|Symbolic integration}}'''<br />
<br />
Symbolic algebra is the basic process of finding an antiderivative function (defined with symbols), as opposed to numerically integrating a function. The title text is a pun that defines the term not as integration that works with symbols, but rather as integration as a symbolic act, as if it were a component of a ritual. A symbolic act in a ritual is an act meant to evoke something else, such as burning a wooden figurine of a person to represent one’s hatred of that person. Alternatively, the reference could be seen as a joke that integration might as well be a symbol, like in a novel, because Randall can't get any meaningful results from his analysis.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[Two flow charts are shown.]<br />
<br />
:[The first flow chart has four steps in simple order, one with multiple recommendations.]<br />
:DIFFERENTIATION<br />
:Start<br />
:Try applying<br />
::Chain Rule<br />
::Power Rule<br />
::Quotient Rule<br />
::Product Rule<br />
::Etc.<br />
:Done?<br />
::No [Arrow returns to "Try applying" step.]<br />
::Yes<br />
:Done!<br />
<br />
[The second flow chart begins like the first, then descends into chaos.]<br />
:INTEGRATION<br />
:Start<br />
:Try applying<br />
::Integration by Parts<br />
::Substitution<br />
:Done?<br />
:Haha, Nope!<br />
<br />
:[Chaos, Roughly from left to right, top to bottom, direction arrows not included.]<br />
::Cauchy's Formula<br />
::????<br />
::???!?<br />
::???<br />
::???<br />
::?<br />
::Partial Fractions<br />
::??<br />
::?<br />
::Install Mathematica<br />
::?<br />
::Riemann Integration<br />
::Stokes' Theorem<br />
::???<br />
::?<br />
::Risch Algorithm<br />
::???<br />
::[Sad face.]<br />
::?????<br />
::???<br />
::What the heck is a Bessel Function??<br />
::Phone calls to mathematicians<br />
::Oh No<br />
::Burn the Evidence<br />
::[More arrows pointing out of the image to suggest more steps.]<br />
<br />
{{comic discussion}}<br />
[[Category:Analysis]]<br />
[[Category:Flowcharts]]</div>172.68.34.118https://www.explainxkcd.com/wiki/index.php?title=2170:_Coordinate_Precision&diff=1760532170: Coordinate Precision2019-07-01T21:02:59Z<p>172.68.34.118: </p>
<hr />
<div>{{comic<br />
| number = 2170<br />
| date = July 1, 2019<br />
| title = Coordinate Precision<br />
| image = coordinate_precision.png<br />
| titletext = 40 digits: You are optimistic about our understanding of the nature of distance itself.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by a CARTOGRAPHER. Provide examples for each table entry. Do NOT delete this tag too soon.}}<br />
<br />
Coordinates are data points used to identify a person's location on the planet Earth. However, a given coordinate covers a square region of land, and thus leaves some ambiguity; thus, greater precision requires an increasing count of decimal points in your coordinates. This comic uses this information to roughly identify how precise a given coordinate length might be.<br />
<br />
The coordinates at [https://tools.wmflabs.org/geohack/geohack.php?pagename=Cape_Canaveral&params=28.5234_N_80.6830_W_type:landmark_region:US-FL_scale:10000 28.5234°N, 80.6830°W] (in {{w|decimal degrees}} form; in {{w|geographic coordinate system}} form using degrees, minutes, and seconds, 28° 31′ 24.24″N, 80° 40′ 58.8″W) are pointing to the {{w|Rocket Garden}} at {{w|Kennedy Space Center}} in {{w|Merritt Island, Florida}} (usually referred to as '''{{w|Cape Canaveral}}''')—specifically, the tip of the [https://www.kennedyspacecenter.com/-/media/DNC/KSCVC/Blog-Images/Rocket-Garden/rocket-garden-with-labels.ashx?h=860&w=1173&la=en&hash=7B9ADC7AFF5370E462AC98D9651945B806B77B2C Delta] rocket.<br />
<br />
The sixth entry in the table, with seven digits of precision, includes the caveat that, while your coordinates map to areas small enough on the Earth's surface to indicate pointing to a specific person in a room, "since you didn't include datum information, we can't tell who". This is a reference to the various ''{{w|geodetic data}}'' or ''geodetic systems'' — different ways of dealing with the fact that the earth is neither perfectly spherical nor perfectly an oblong ellipsoid. The various data do not make much difference at six digits of precision, but at seven, there is enough skew depending on which system is in use that the person in a room you are referring to with the coordinates is ambiguous. It is unstated, but the remaining lines in the table with ever-greater precision suffer from this same issue and are equally ambiguous without datum information.<br />
<br />
The final entry, with seventeen digits of precision, suggests that either the user is referring to individual atoms in the much-larger-scale whole-Earth coordinate system, or (perhaps more likely) has interpreted bad memory data as floating-point numbers due to a software error. Floating-point numbers with much more precision than expected often indicate that a variable was overwritten with junk data; in this case, the extra precision would be meaningless.<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[Single panel containing a table with two columns for "Lat/Lon Precision" and "Meaning" and a caption above the table.]<br />
:Caption: What The Number of Digits in Your Coordinates Means<br />
<br />
:[Row 1]<br />
:Lat/Lon: 28&deg;N, 80&deg;W<br />
:Meaning: You're probably doing something space-related<br />
<br />
:[Row 2]<br />
:Lat/Lon: 28.5&deg;N, 80.6&deg;W<br />
:Meaning: You're pointing out a specific city<br />
<br />
:[Row 3]<br />
:Lat/Lon: 28.52&deg;N, 80.68&deg;W<br />
:Meaning: You're pointing out a neighborhood<br />
<br />
:[Row 4]<br />
:Lat/Lon: 28.523&deg;N, 80.683&deg;W<br />
:Meaning: You're pointing out a specific suburban cul-de-sac<br />
<br />
:[Row 5]<br />
:Lat/Lon: 28.5234&deg;N, 80.6830&deg;W<br />
:Meaning: You're pointing to a particular corner of a house<br />
<br />
:[Row 6]<br />
:Lat/Lon: 28.52345&deg;N, 80.68309&deg;W<br />
:Meaning: You're pointing to a specific person in a room, but since you didn't include datum information, we can't tell who<br />
<br />
:[Row 7]<br />
:Lat/Lon: 28.5234571&deg;N, 80.6830941&deg;W<br />
:Meaning: You're pointing to Waldo on a page<br />
<br />
:[Row 8]<br />
:Lat/Lon: 28.523457182&deg;N, 80.683094159&deg;W<br />
:Meaning: "Hey, check out this specific sand grain!"<br />
<br />
:[Row 9]<br />
:Lat/Lon: 28.523457182818284&deg;N, 80.683094159265358&deg;W<br />
:Meaning: Either you're handing out raw floating point variables, or you've built a database to track individual atoms. In either case, please stop.<br />
<br />
{{comic discussion}}</div>172.68.34.118https://www.explainxkcd.com/wiki/index.php?title=1513:_Code_Quality&diff=1759601513: Code Quality2019-06-29T13:41:09Z<p>172.68.34.118: Removed parts talking about the Code Quality series as a whole, since they can easily become out-of-date and don't help to explain this specific comic.</p>
<hr />
<div>{{comic<br />
| number = 1513<br />
| date = April 17, 2015<br />
| title = Code Quality<br />
| image = code quality.png<br />
| titletext = I honestly didn't think you could even USE emoji in variable names. Or that there were so many different crying ones.<br />
}}<br />
<br />
==Explanation==<br />
This comic is the first in the [[:Category:Code Quality|Code Quality]] series. <br />
<br />
It is about the apprehension of asking for help from an expert who is a friend. Often we fear that we will be judged and they will think less of us, which is what occurs in this comic.<br />
<br />
[[Ponytail]] is about to look at some {{w|source code}} [[Cueball]] has written, and he is warning her that he is self-taught so his code probably won't be written the way she is used to. In spite of Ponytail's initial (polite) optimism, she comments in three increasingly harsh similes (and a fourth in the title text).<br />
<br />
First, she suggests that reading his code is like being in a house built by a child, using a hatchet (a small ax) to put together what he thought was a house based on a picture. She is saying that the code shows a lack of command of the language being programmed. This is like the common expression "If all you have is a hammer, everything looks like a nail." New programmers make use of the same techniques repeatedly, using them for situations that they are not intended for.<br />
<br />
Second, she suggests that it looks like a salad recipe, written by a corporate lawyer on a phone with auto-correct that only corrected things to formulas from Microsoft Excel. She is saying that the code is verbose and the corrections that were done are illogical. This presumably relates to the developer not being an expert in their craft, and fixing the problems as they come up instead of reexamining the problem and solving it in a better way.<br />
<br />
Third, she describes it as a transcript of a couple arguing at a branch of the Swedish retail chain {{w|IKEA}}, which was then randomly edited until the computer compiled it with no errors. She is saying that the intent of the code is unclear due to the seemingly random use of the language. This is very similar to an infinite amount of monkeys bashing away on typewriters for an infinite amount of time eventually producing the complete works of Shakespeare. (A couple's argument may be even less coherent at IKEA than at the average store, since IKEA products always have idiosyncratic names and many of them are difficult to pronounce or transcribe for anyone who doesn't speak Swedish.) This might happen if the code was written so bad that it does not compile, and people edited the code until it compiles so they can see what the code accomplishes. That Cueball's code is in this bad a shape indicates he really hasn't learned the programming language; he just happens to have a program that works in some shape or fashion. <br />
<br />
Finally, Cueball makes the rather weak assurance that he will read "a style guide", which articulates the intended use of the language. It seems clear from Ponytail's commentary that his {{w|Software quality|code quality}} would benefit from far more training in computer programming.<br />
<br />
The title text refers to {{w|emoji}}. Ponytail's comment implies that some of Cueball's variables contained emoji, perhaps in an effort to capture the emotional content of the arguments which show through the requirements document. Emoji has become a [[:Category:Emoji|recurrent theme]] on xkcd, but this may have been the first comic to use them for a pun.<br />
<br />
===Emoji===<br />
Many crying-face emoji are possible if variables can include full Unicode (e.g., 😢,😭,😂,😿,😹), as well as faces with sweat drops that are often mistaken for tears (😪,😥,😰). In some programming languages it would be impossible to use them in variable names, as the symbols would break the language's syntax rules. Exceptions to this include {{w|Swift (programming language)|Swift}} and {{w|Perl|Perl}} ([http://perldoc.perl.org/5.24.0/perlunicode.html]), but most languages with compilers that support Unicode characters can include this kind of emoji, even for languages that predate Unicode like {{w|C++}} and {{w|Lisp_(programming_language)|Lisp}}.<br />
<br />
In any event, Cueball's code may best be represented by a bunch of people crying, as that is the only proper response to it.<br />
<br />
===Programming Style===<br />
Although few programming languages require a perfectly rigid style, so long as the code is syntactically accurate, most programmers follow some sort of {{w|Programming style|style}} to make the code easier to read. This includes indenting lines to show levels and using descriptive variable identifiers with special capitalization, (e.g., {{w|camelCase}}, capitalizing each word except for the first in a sentence, or {{w|snake_case}}, separating lowercase words with underscores).<br />
<br />
==Transcript==<br />
:[Cueball showing Ponytail his laptop.]<br />
:Cueball: Keep in mind that I'm self-taught, so my code may be a little messy.<br />
:Ponytail: Lemme see - I'm sure it's fine.<br />
<br />
:[Ponytail sits at desk, Cueball stand behind her.]<br />
:Ponytail: ...Wow. This is like being in a house built by a child using nothing but a hatchet and a picture of a house.<br />
<br />
:[Ponytail sits at desk, Cueball stand behind her.]<br />
:Ponytail: It's like a salad recipe written by a corporate lawyer using a phone autocorrect that only knew Excel formulas.<br />
<br />
:[Ponytail sits at desk, Cueball stand behind her.]<br />
:Ponytail: It's like someone took a transcript of a couple arguing at IKEA and made random edits until it compiled without errors.<br />
:Cueball: '''''Okay,''''' I'll read a style guide.<br />
<br />
==Trivia==<br />
*Emoji can be simulated using {{w|ASCII}} characters, but their roots are mostly separate from ASCII {{w|emoticon}}s. Most languages will allow variable names to include underscores, so some sad face ASCII emoticon will be legal variable names, such as <code>T_T</code>, <code>p_q</code>, <code>ioi</code> etc., but such things rarely show up in software variables. Many more can be made possible using [http://hexascii.com/sad-emoticons/ UTF-8 characters].<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Code Quality]]<br />
[[Category:Comics sharing name|Code Quality 01]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Ponytail]]<br />
[[Category:Programming]]<br />
[[Category:Computers]]<br />
[[Category:Language]]<br />
[[Category:Emoji]]<br />
[[Category:Cueball Computer Problems]]</div>172.68.34.118https://www.explainxkcd.com/wiki/index.php?title=1677:_Contrails&diff=1670641677: Contrails2018-12-16T13:51:42Z<p>172.68.34.118: /* Explanation */</p>
<hr />
<div>{{comic<br />
| number = 1677<br />
| date = May 6, 2016<br />
| title = Contrails<br />
| image = contrails.png<br />
| titletext = Astronomy (or "astrology" in British English) is the study of...<br />
}}<br />
<br />
==Explanation==<br />
{{w|Contrail}}s (short for "condensation trails") are trails of vapor produced by aircraft exhaust, trailing the airplane. They are formed from water condensing on jet fuel exhaust particles, some impurities of which provide bases for ice crystals to accumulate on. Some can dissipate in minutes, but others can last for hours or even longer, depending on the temperature, relative humidity and wind conditions at that particular altitude. Long-lasting contrails is a sign of high relative humidity and may sometimes predict the formation of clouds and rain. The {{w|chemtrail conspiracy theory}} claims that contrails lasting unusually long are actually chemical or biological agents sprayed into the air for sinister purposes. There is no known evidence that such a thing is happening.<br />
<br />
Here, [[White Hat]] notices that there are a lot of contrails in the air. [[Cueball]] corrects him, saying that in {{w|American English}}, contrails are called chemtrails, which is incorrect.<br />
<br />
This is a comic in the [[:Category:My Hobby|My Hobby]] series. Some of these comics involve [[Cueball]] giving misleading information about pedantic terms, such as [[1405: Meteor]]. Another of these comics, [[966: Jet Fuel]], even mentions chemtrails, saying that they are made of mind-control agents carried on board the planes that make them. Later they were again mentioned in [[1803: Location Reviews]].<br />
<br />
The title text includes a similar situation, implying that {{w|astronomy}} and {{w|astrology}} are synonymous, with astrology being the term used in British English. However, this is incorrect. Astronomy is the scientific study of things in outer space, like stars, planets, and galaxies, whereas astrology is a system that infers a person's personality and characteristics from those same things in outer space. Though both involve studying celestial objects, astrology is considered a pseudoscience rather than an empirical science.<br />
<br />
The joke is that {{w|British English}} and American English use different terms to refer to the same object, and one can often learn new words for a simple thing. This, however is not the case in this comic; contrail and chemtrail do not refer to the same thing, the latter being only a conspiracy theory.<br />
<br />
This newfound hobby is developing to another hobby about spreading misinformation that was released less than two month after this: [[1697: Intervocalic Fortition]].<br />
<br />
==Transcript==<br />
:[Cueball and a White Hat are walking. White Hat is looking up to the sky while Cueball, walking in front holds out one arm towards him.]<br />
:White Hat: Lots of contrails today.<br />
:Cueball: Oh, you must be from the UK. In American English it's "Chemtrail".<br />
<br />
:[Caption below the panel:]<br />
:My hobby: Spreading linguistic misinformation<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics featuring White Hat]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:My Hobby]]<br />
[[Category:Conspiracy theory]]<br />
[[Category:Language]]</div>172.68.34.118