https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&user=172.68.226.46&feedformat=atomexplain xkcd - User contributions [en]2024-03-29T01:53:25ZUser contributionsMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=Talk:2298:_Coronavirus_Genome&diff=191190Talk:2298: Coronavirus Genome2020-04-24T23:05:37Z<p>172.68.226.46: </p>
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Epigenetics is a pun, right? I think it's a pun but I don't know what and it's maddening. [[User:Jacky720|That's right, Jacky720 just signed this]] ([[User talk:Jacky720|talk]] | [[Special:Contributions/Jacky720|contribs]]) 23:03, 24 April 2020 (UTC)<br />
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since when does notepad have spellcheck? [[Special:Contributions/172.68.226.46|172.68.226.46]] 23:05, 24 April 2020 (UTC)</div>172.68.226.46https://www.explainxkcd.com/wiki/index.php?title=2295:_Garbage_Math&diff=1908882295: Garbage Math2020-04-18T12:27:17Z<p>172.68.226.46: /* Explanation */</p>
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<div>{{comic<br />
| number = 2295<br />
| date = April 17, 2020<br />
| title = Garbage Math<br />
| image = garbage_math.png<br />
| titletext = 'Garbage In, Garbage Out' should not be taken to imply any sort of conservation law limiting the amount of garbage produced.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by a ZILOG Z80. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}<br />
This comic explains the "{{w|garbage in, garbage out}}" concept using arithmetical expressions. Just like the comic says, if you get garbage in any part of your workflow, you get garbage as a result.<br />
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Some of these rules correspond to the rules of {{w|floating point arithmetic}}, while others may be inspired by the rules of {{w|Propagation_of_uncertainty#Example_formulae| propagation of uncertainty}} where a "garbage" number would correspond to an estimate with a high degree of uncertainty, and the uncertainty of the result of arithmetic operations will tend to be dominated by the term with the highest uncertainty. The rule about N pieces of independent garbage reflects the {{w|central limit theorem}} and how it predicts that the uncertainty (or {{w|standard error}}) of an estimate will be reduced when independent estimates are averaged. The comic oddly omits raising garbage to the 0th power, which transforms even NaN, the platonic ideal of garbage, to exactly 1.<br />
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This comic is not related to the {{w|2019–20 coronavirus outbreak|2020 pandemic}} of the {{w|coronavirus}} {{w|SARS-CoV-2}}, which causes {{w|COVID-19}}, breaking the streak of comics preceding this on [[:Category:COVID-19|topics relating to COVID-19]], after (rather appropriately) 19 comics (not counting the [[2288: Collector's Edition|April Fools' comic]]).<br />
<br />
This comic is about the propagation of errors in numerical analysis and statistics, but described in much more colloquial terms. Numbers with low precision are termed "garbage" and numbers with high precision are labeled "precise".<br />
<br />
{| class="wikitable"<br />
!Formula<br />
!Statistical Expression<br />
!Explanation<br />
|-<br />
|Precise number + Precise number = Slightly less precise number<br />
|<math>\mathop\sigma(X+Y)=\sqrt{(\mathop\sigma(X))^2+(\mathop\sigma(Y))^2}</math><br />
|If we know absolute error bars, then adding two precise numbers will at worst add the sizes of the two error bars. For example, if our precise numbers are 1 (±10<sup>-6</sup>) and 1 (±10<sup>-6</sup>), then our sum is 2 (±2·10<sup>-6</sup>). It is possible to lose a lot of relative precision, if the resultant sum is close to zero as a result of adding a number and then close to its inverse. This phenomenon is known as catastrophic cancellation. Therefore, it is likely that all numbers referred here are positive numbers, which does not exhibit this phenomenon.<br />
|-<br />
|Precise number × Precise number = Slightly less precise number<br />
|<math>\mathop\sigma(X\times Y)=\sqrt{(\mathop\sigma(X)\times Y)^2+(\mathop\sigma(Y)\times X)^2}</math><br />
|Here, instead of absolute error, relative error will be added. For example, if our precise numbers are 1 (±10<sup>-6</sup>) and 1 (±10<sup>-6</sup>), then our product is 1 (±2·10<sup>-6</sup>).<br />
|-<br />
|Precise number + Garbage = Garbage<br />
|<math>\mathop\sigma(X+Y)=\sqrt{(\mathop\sigma(X))^2+(\mathop\sigma(Y))^2}</math><br />
|If one of the numbers has a high absolute error, and the numbers being added are of comparable size, then this error will be propagated to the sum. <br />
|-<br />
|Precise number × Garbage = Garbage<br />
|<math>\mathop\sigma(X\times Y)=\sqrt{(\mathop\sigma(X)\times Y)^2+(\mathop\sigma(Y)\times X)^2}</math><br />
|Likewise, if one of the numbers has a high relative error, then this error will be propagated to the product. Here, this is independent of the sizes of the numbers.<br />
|-<br />
|<math>\sqrt{\text{Garbage}} = \text{Less bad garbage}</math><br />
|<math>\mathop\sigma(\sqrt X)=\frac{\mathop\sigma(X)}{2\times\sqrt X} </math><br />
| When the square root of a number is computed, its relative error will be halved. Depending on the application, this might not be all that much ''better'', but it's at least ''less bad''.<br />
|-<br />
|Garbage<sup>2</sup> = Worse garbage<br />
|<math>\mathop\sigma(X^2)=2\times X\times\mathop\sigma(X)</math><br />
|Likewise, when a number is squared, its relative error will be doubled. This is a corollary to multiplication adding relative errors.<br />
|-<br />
|<math>\frac{1}{N}\sum(\text{N pieces of statistically independent garbage}) = \text{Better garbage}</math><br />
|<br />
|By aggregating many pieces of statistically independent observations (for instance, surveying many individuals), it is possible to reduce relative error. This is the basis of statistical sampling.<br />
|-<br />
|Precise number<sup>Garbage</sup> = Much worse garbage<br />
|<math>\mathop\sigma(b^X)=b^{2\times X}\times\mathop{\mathrm{ln}}b\times\sigma(X)</math><br />
|The exponent is very sensitive to changes, which may also magnify the effect based on the magnitude of the precise number.<br />
|-<br />
|Garbage – Garbage = Much worse garbage<br />
|<math>\mathop\sigma(X-Y)=\sqrt{(\mathop\sigma(X))^2+(\mathop\sigma(Y))^2}</math><br />
|This line involves catastrophic cancellation. If both pieces of garbage are about the same (e.g. if their error bars overlap), then it is possible that the answer is positive, zero, or negative.<br />
|-<br />
|<math>\frac{\text{Precise number}}{\text{Garbage}-\text{Garbage}}</math> = Much worse garbage, possible division by zero<br />
|<br />
|Indeed, as with above, if error bars overlap then we might end up dividing by zero.<br />
|-<br />
|Garbage × 0 = Precise number<br />
|<math>\mathop\sigma(0)=0</math><br />
|Multiplying anything by 0 results in 0, an extremely precise number in the sense that it has no error whatsoever since we supply the 0 ourselves. This is equivalent to discarding garbage data from a statistical analysis.<br />
|}<br />
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The title text refers to the computer science maxim of "garbage in, garbage out," which states that when it comes to computer code, supplying incorrect initial data will produce incorrect results, even if the code itself accurately does what it is supposed to do. As we can see above, however, when plugging data into mathematical formulas, this can possibly magnify the error of our input data, though there are ways to reduce this error (such as aggregating data). Therefore, the quantity of garbage is not necessarily conserved.<br />
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==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
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[A series of mathematical equations are written from top to bottom]<br />
<br />
Precise number + Precise number = Slightly less precise number<br />
<br />
Precise number × Precise number = Slightly less precise number<br />
<br />
Precise number + Garbage = Garbage<br />
<br />
Precise number × Garbage = Garbage<br />
<br />
√<span style="border-top:1px solid; padding:0 0.1em;">Garbage</span> = Less bad garbage<br />
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1/N Σ (N pieces of statistically independent garbage) = Better garbage<br />
<br />
(Precise number)<sup>Garbage</sup> = Much worse garbage<br />
<br />
Garbage – Garbage = Much worse garbage<br />
<br />
Precise number / ( Garbage – Garbage ) = Much worse garbage, possible division by zero<br />
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Garbage × 0 = Precise number<br />
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{{comic discussion}}<br />
[[Category:Math]]</div>172.68.226.46https://www.explainxkcd.com/wiki/index.php?title=Talk:2272:_Ringtone_Timeline&diff=187736Talk:2272: Ringtone Timeline2020-02-25T00:56:49Z<p>172.68.226.46: Nitpicking</p>
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Doing the Title Text. [[User:Netherin5|“That Guy from the Netherlands”]] ([[User talk:Netherin5|talk]]) 18:07, 24 February 2020 (UTC)<br />
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What about the era of "I would love to set my phone to a traditional ringing sound but this weird space garbage is the closest my phone will get"? [[Special:Contributions/173.245.54.61|173.245.54.61]] 18:53, 24 February 2020 (UTC)<br />
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I've got my smartphone set to the classic monophoncic Nokia 3310 tune. You can easily tell the >25y from the <25y generation apart from their reaction. [[User:Gir|-- //gir.st/]] ([[User talk:Gir|talk]]) 19:22, 24 February 2020 (UTC)<br />
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I wonder if Randal actually found some data to support his timeline or if it's more of a general observation made by him. In my subjective experience, the trend towards having the phone on vibrate all the time has been going on since at least 2017-2018 rather than the future/present time indicated in his timeline. [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 19:41, 24 February 2020 (UTC)<br />
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Early ringers were hand-cranked generators (or perhaps magnetos), so you might be able to tell who was calling by how fast they cranked.[[Special:Contributions/172.68.206.22|172.68.206.22]] 19:51, 24 February 2020 (UTC)<br />
:No, in that period it was mostly still operators. I suppose you would know which operator was on duty, if your area was small enough. [[User:SDSpivey|SDSpivey]] ([[User talk:SDSpivey|talk]]) 22:07, 24 February 2020 (UTC)<br />
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Party lines shared the signal and differentiated the callee by ring. I grew up on 19-ring-12, i.e. line 19 (on the manual switchboard in the village) ringing one long and two short. There was a magneto, but you used it to request the operator to give you a line for an outgoing call; it signaled the switchboard, not another party.<br />
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I remember around 1982 staying over at a friend's house and hearing the electronic tweedling of their new landline phone and not knowing what it was. Prior to that all the phones I'd heard at homes, businesses, school, etc. were all normal ringers. So the cool space beeps starting around 1996 seems skewed to the right by about a decade. [[Special:Contributions/172.68.38.124|172.68.38.124]] 20:21, 24 February 2020 (UTC)Pat<br />
: There's obviously plenty of overlap, and I think the boxes represent when a particular style was prevalent, not the entire duration. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 20:37, 24 February 2020 (UTC)<br />
: In the UK, the so-called trimphone was introduced in the sixties with a warbling ringtone instead of the traditional bell sound. [[Special:Contributions/162.158.159.12|162.158.159.12]] 23:12, 24 February 2020 (UTC)<br />
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Interesting contrast to [https://xkcd.com/479/ xkcd 479].<br />
[[User:LHN|LHN]]<br />
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I would like to point out that "a phone on vibrate sitting on a hard surface" may not have been receiving a call at the time of the audio recording so technically Randall's ringtone could be utter silence (or a very low coil whine). [[Special:Contributions/172.68.226.46|172.68.226.46]] 00:56, 25 February 2020 (UTC)</div>172.68.226.46https://www.explainxkcd.com/wiki/index.php?title=Talk:2245:_Edible_Arrangements&diff=185092Talk:2245: Edible Arrangements2019-12-24T07:48:18Z<p>172.68.226.46: </p>
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<div>How often do typos show up in XKCD comics ("Edible Arrangements is a thing" versus "Edible Arrangements are a thing")? [[User:Capncanuck|Capncanuck]] ([[User talk:Capncanuck|talk]]) 20:36, 23 December 2019 (UTC)<br />
:It's not a typo. Randall is referring to the concept of Edible Arrangements, not a collection of edible arrangements. [[Special:Contributions/162.158.63.220|162.158.63.220]] 20:56, 23 December 2019 (UTC)<br />
::I see what you mean. Should there have been quotes around the terms in the first panel then? [[User:Capncanuck|Capncanuck]] ([[User talk:Capncanuck|talk]]) 20:58, 23 December 2019 (UTC)<br />
:::Nevermind, it's a company name. no quotes needed. [[User:Capncanuck|Capncanuck]] ([[User talk:Capncanuck|talk]]) 21:04, 23 December 2019 (UTC)<br />
"Any arrangement is an edible arrangement if you're hungry enough." - and you have enough mustard. Happy Winter Solstice Everyone![[Special:Contributions/172.68.226.46|172.68.226.46]] 07:48, 24 December 2019 (UTC)</div>172.68.226.46https://www.explainxkcd.com/wiki/index.php?title=2232:_Hotel_Room_Party&diff=1835032232: Hotel Room Party2019-11-23T02:40:55Z<p>172.68.226.46: /* Trivia */</p>
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<div>{{comic<br />
| number = 2232<br />
| date = November 22, 2019<br />
| title = Hotel Room Party<br />
| image = hotel_room_party.png<br />
| titletext = [proudly greeting the hotel manager at the door] "Did I do aa good job?"<br />
}}<br />
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==Explanation==<br />
{{incomplete|Created by a TRASHED HOTEL ROOM. Please mention here why this explanation isn't complete. Do NOT delete this tag too soon.}}<br />
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It is a common trope that really wild parties in hotel rooms, particularly by rock bands on tour, end up trashing that hotel room as crazy party goers break and spill things. Such parties are widely perceived to be very fun, because they got so out of control. In this comic, [[Cueball]] (together with [[Hairy]], [[Ponytail]], [[White Hat]], [[Megan]], and [[Blondie]]) is misunderstanding cause and effect as he plans to throw a party where you trash a hotel room. Instead of planning a wild party, he is planning to calmly and deliberately trash the hotel room by assigning people to do damage. Unlike a real wild party, this is unlikely to be fun{{Citation needed}} to anyone but hardcore geeks. Also, because Cueball is so organized, he is also planning for maintenance and cleaning services to undo the damage, or at least make it easier to dispose of. Since what is shown of such parties is the aftermath, one could argue that leaving the damage is part of the point.<br />
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In actual trash-a-hotel-room parties the party goers are so hungover or tired afterward that they don't clean up but leave the damage. This often results in rock bands being charged large amounts of money after the fact for the hotel to do the repairs.<br />
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In addition to rock bands, trashing of hotel rooms are also featured in the Tailhook scandal of 1991, where naval officers [https://books.google.com/books?id=E6YY2P0C8wkC&pg=PA82&lpg=PA82&dq=tailhook+chainsaw&source=bl&ots=RCKVl3BThT&sig=ACfU3U2YI2QhSLY2RgXQqLCkl3tc6DO3tA&hl=en&sa=X&ved=2ahUKEwjttqCfqv7lAhXlJDQIHUsSCEgQ6AEwC3oECAkQAQ#v=onepage&q=tailhook%20chainsaw&f=false cut down a wall between two hotel suites with a chainsaw]. [https://tvtropes.org/pmwiki/pmwiki.php/Main/WildTeenParty Trashing a home during a teenage party] while parents are away, and the mad rush to clean up the damage/evidence before the parents return, is a common trope in teen movies.<br />
<br />
==Transcript==<br />
:[ [[Hairy]], [[Ponytail]], [[Cueball]], [[White Hat]], [[Megan]], and [[Blondie]] are standing in a line. Cueball is raising his left hand with his pointer finger extended and is facing his left. He is also pointing to the right. The other five are facing Cueball.]<br />
:Cueball: OK everyone, let's break into teams.<br />
:Cueball: Katie, get the wire cutters and start disassembling the TV. You two can strip the wallpaper. Mike and I will work on shredding the mattress.<br />
:Cueball: You, start shopping for maintenance and cleaning services. We don't want to leave the staff to deal with this.<br />
<br />
:[Caption below the panel]: It's my first time throwing one of those parties where you trash a hotel room and I want to make sure I get it right.<br />
<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Hairy]]<br />
[[Category:Comics featuring Ponytail]]<br />
[[Category:Comics featuring White Hat]]<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Comics featuring Blondie]]<br />
<br />
== Trivia ==<br />
* The title text to this comic originally read '[proudly greeting the hotel manager at the door] "Did I do aa good job?"' It is not clear if the 'aa' is a typo, or intentionally representing someone slurring their words because they are drunk or hung over from a party.<br />
* Cueball gives instructions to a 'Mike' and a 'Katie' while giving instructions. Since Megan has a specific name, this suggests that either Ponytail or Blondie are named Katie, while either Hairy or White Hat are named Mike – provided that Randall's character models always correspond to one specific person each, which is highly dubious.<br />
<br />
{{comic discussion}}<br />
<br />
[[Category:Comics featuring Megan]]<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Comics featuring Hairy]]<br />
[[Category:Comics featuring Ponytail]]<br />
[[Category:Comics featuring White Hat]]<br />
[[Category:Comics featuring Blondie]]</div>172.68.226.46https://www.explainxkcd.com/wiki/index.php?title=Talk:2227:_Transit_of_Mercury&diff=182836Talk:2227: Transit of Mercury2019-11-13T13:30:47Z<p>172.68.226.46: </p>
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In the title text, the filter probably refers to a pool filter used for cleaning the pool while the green stuff is algae that is growing in the water. As a personal note, owning a pool and paying the water bills for it is not something I can relate to. [[Special:Contributions/162.158.62.81|162.158.62.81]] 22:33, 11 November 2019 (UTC)<br />
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[[1828: ISS Solar Transit]], Anyone? [[Special:Contributions/162.158.62.105|162.158.62.105]] 23:08, 11 November 2019 (UTC)<br />
:Just added a little blurb about that; thanks for noticing.--[[User:Account|Account]] ([[User talk:Account|talk]]) 01:33, 12 November 2019 (UTC)<br />
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The transcript is wrong about there being no details visible in the image. A small black dot is visible on the upper-right side which is presumably Mercury. [[Special:Contributions/162.158.159.58|162.158.159.58]] 09:04, 12 November 2019 (UTC)<br />
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The transcript is supposed to be text-only to allow screen readers for the visually-impaired people. How should we include the embedded smiley in the caption using just text? [[User:Ianrbibtitlht|Ianrbibtitlht]] ([[User talk:Ianrbibtitlht|talk]]) 14:20, 12 November 2019 (UTC)<br />
: I didn't even see it, in the transcript, and it was just a square 'unknown char' upon editing. I decided to try the "non-literal descriptions are in square-parens" method, but that might not be the right method, and I have no idea if it's the right Unicode name... but it seems to do what's necessary, unless anyone wishes to revert/redo as per other examples of similar inclusions on this site. [[Special:Contributions/162.158.159.58|162.158.159.58]] 14:34, 12 November 2019 (UTC)<br />
::We do use emojis in the transcript here on this page. See other comics with emoji --[[User:Kynde|Kynde]] ([[User talk:Kynde|talk]]) 14:59, 12 November 2019 (UTC)<br />
:::As far as I'm aware, most screen readers / TTS engines simply read the Unicode name for the character (eg. 😎 translates to ''Smiling Face With Sunglasses''). See [https://veroniiiica.com/2018/07/17/how-do-people-with-vision-impairments-use-emoji/ this blog post] for more on the issue. --[[Special:Contributions/172.68.226.46|172.68.226.46]] 13:30, 13 November 2019 (UTC)<br />
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Is there milage (or perhaps Astronomical Unitage?) in mentioning that an Instagram-esque 'filter' adds, or otherwise overwrites, a set of pixels whilst an optical filter ''subtracts'' a proportion of the photons? [[Special:Contributions/162.158.159.58|162.158.159.58]] 14:24, 12 November 2019 (UTC)<br />
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I’ve no clue where this belongs (trivia?), but it seems worth noting. Tuesday, November 12, the New York Times began a “new column” titled ''Good Question.'' First piece is Randall answering [https://www.nytimes.com/2019/11/12/science/randall-munroe-moon.html If I Touched the Moon, What Would It Feel Like?]” Idk if this is a new Randall column, or will have different contributors. [[User:Miamiclay|Miamiclay]] ([[User talk:Miamiclay|talk]]) 20:20, 12 November 2019 (UTC)<br />
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Thanks for the link to the NYTimes article. I was, however, greatly saddened to find the pictures had no hover-text. what-if.xkcd.com has spoiled me. [[User:Cellocgw|Cellocgw]] ([[User talk:Cellocgw|talk]]) 13:28, 13 November 2019 (UTC)<br />
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[https://vim.cx/?5b4d62ce18cdf9cc#8fpkb3edtPageWAsST4RipUpWEYZqapp9fpeFi7knFzW #nofilter] [[User:Temp9867856745|Temp9867856745]] ([[User talk:Temp9867856745|talk]]) 02:56, 13 November 2019 (UTC)</div>172.68.226.46https://www.explainxkcd.com/wiki/index.php?title=2170:_Coordinate_Precision&diff=1816512170: Coordinate Precision2019-10-23T20:43:10Z<p>172.68.226.46: /* Chart */ irrelevant observation</p>
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<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 />
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==Explanation==<br />
<br />
<br />
This cartoon gives increasingly precise latitude and longitude coordinates for a 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 increasing precision of coordinates in this cartoon are similar to the increasing magnification in the short documentary {{w|Powers of Ten (film)|"Powers of 10,"}} which can be found [http://www.youtube.com/watch?v=0fKBhvDjuy0 here]. (Also parodied in [[271|#271:Powers of One]]).<br />
<br />
The coordinates at [https://tools.wmflabs.org/geohack/geohack.php?pagename=Cape_Canaveral&params=28.52345_N_80.68309_W_type:landmark_region:US-FL_scale:10000 28.52345°N, 80.68309°W] (in {{w|decimal degrees}} form; in {{w|geographic coordinate system}} form using degrees, minutes, and seconds, 28° 31′ 24.24.4″N, 80° 40′ 59.1″W) are pointing to the {{w|Rocket Garden}} at the {{w|Kennedy Space Center}} in {{w|Merritt Island, Florida}} —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 />
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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 ''{{w|geodetic datum}}'' or ''geodetic system'' — different ways of dealing with the fact that the earth is neither perfectly spherical nor perfectly an oblong ellipsoid. The various datums 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 not bothered to format the values from the GPS module for viewing in the software UI in any way whatsoever, resulting in a value that is {{w|False precision|meaninglessly precise}} because the measurement wasn't that {{w|Accuracy and precision|accurate}} to begin with. Even if the value is accurate, locating individual atoms by coordinates is not actually useful in most cases, and the motions of multiple systems within our physical world (continental drift, subtle vibrations, {{w|Brownian motion}}, etc.) would render the precise value obsolete rather quickly.<br />
<br />
For the decimal places past the 5th on the latitude, the digits given are actually the first part of the decimal expansion of the constant ''e'' (2.7182818284), while for the decimal places past the 5th on the longitude, the digits given are part of the decimal expansion of the constant ''π'' (3.14159265358) starting with the second digit (4).<br />
<br />
The title text references how at sufficiently small distances, our understanding of reality itself begins to break down. Smaller than the {{w|Planck length}}, which is more than a quintillion times smaller than the diameter of a proton, the ideals of Euclidean geometry no longer apply and space itself may be composed of a {{w|quantum foam}} where the very geometry of spacetime itself fluctuates, meaning coordinate systems based on an assumption that space doesn't change would no longer work. String theory, on the other hand, assumes that at a short enough distance the world is composed of ten space dimensions, which precludes the use of a two-dimensional coordinate system (not that our “normal” three dimensions don't do so in themselves).<br />
<br />
The actual number of longitude digits needed to identify a point to a particular precision depends on its latitude. Near the poles, you need fewer longitude digits than at the equator – starting with one digit fewer at around lat. 85°, past all constantly inhabited human settlements, and with two digits fewer at lat. 89.5°, inaccessible to anyone but polar researchers and the occasional guided tour. The number of latitude digits for some particular accuracy stays essentially the same everywhere.<br />
<br />
==Chart==<br />
<br />
{| class="wikitable"<br />
|-<br />
! Decimal places<br />
! Resolution*<br />
! In the comic<br />
! Location<br />
! Explanation/notes<br />
|-<br />
| 0<br />
| <span style="white-space: nowrap;">110 km (70 mi)</span><br />
| Something space-related<br />
| Somewhere near the east coast of Florida<br />
| This resolution is enough to point out a large-scale feature like a country, a mountain range, a large lake, or a significant island on a map of the world. It can also be used to tell if certain celestial phenomena are visible from a given location.<br />
|-<br />
| 1<br />
| 11 km (7&nbsp;mi)<br />
| A specific city<br />
| <span style="white-space: nowrap;">Cape Canaveral</span><br />
| Cities typically span a couple kilometers/miles in diameter and are far enough from each other to distinguish them at this resolution. There are exceptions though, and the veracity of this statement depends greatly on the definition of a “city”, which varies by location and history.<br />
|-<br />
| 2<br />
| 1.1 km (¾&nbsp;mi)<br />
| <span style="white-space: nowrap;">A neighborhood</span><br />
| <span style="white-space: nowrap;">Kennedy Space Center</span> Visitor Complex<br />
|<br />
|-<br />
| 3<br />
| 110 m (360&nbsp;ft)<br />
| <span style="white-space: nowrap;">A suburban cul-de-sac</span><br />
| The Rocket Garden at the Kennedy Space Center<br />
|<br />
|-<br />
| 4<br />
| 11 m (36&nbsp;ft)<br />
| A particular corner of a house<br />
| Somewhere near the center of the Rocket Garden<br />
|<br />
|-<br />
| 5<br />
| 1.1 m (3½&nbsp;ft)<br />
| A specific person in a room (given geodetic datum information)<br />
| 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 Thor-Delta] rocket in Rocket Garden<br />
| As the comic notes, the differences between {{w|geodetic datum}}s – different ways to map geodetic coordinates to specific points on the Earth's surface – become large enough that one needs to specify the one in use when supplying coordinates to this degree of precision (or greater, of course). Since the Earth is not a perfect ellipsoid, different parts of the planet conform best to ellipsoids of slightly different proportions, resulting in different coordinates for a specific location; not to mention that locally used datums have local reference points, which means that the local and global standards are slowly drifting away from each other with the tectonical plates.<br />
Note that the comment in the comic concerns only the {{w|North American Datum|NAD 1983}} datum which is fairly close to the international, “one size fits all” standard {{w|WGS-84}}. Other datums may be shifted by tens or even hundreds of meters (yards), making geodetic datum specification necessary for less precise coordinates as well.<br />
|-<br />
| 7<br />
| 1.1 cm (⁷⁄₁₆&nbsp;in)<br />
| Waldo on a page<br />
| Presumably the very tip of the rocket<br />
| This refers to ''{{w|Where's Wally?|Where's Waldo?}}'', a series of books and magazines containing various scenes (densely packed with people) where one must find Waldo, a character wearing a red and white striped shirt. In the puzzles, he usually stands less than 2 cm (1 in) tall.<br />
Finding Waldo on a page using satellites was also referenced in [[1358:_NRO|#1358]].<br />
|-<br />
| 9<br />
| 0.11 mm (4⅜&nbsp;thou)<br />
| A specific grain of sand<br />
| rowspan=3 | N/A<br />
|<br />
|-<br />
| 15<br />
| 110 pm (1.1&nbsp;Å)<br />
| Raw floating point precision or an individual atom<br />
| A double-precision (64-bit) floating point variable stores 52 significant bits (with an implicit 1 in front), so that 180.00000000000000 and 179.99999999999997 may be represented as distinct values. (This is only 14 decimals, however; the larger the integral part, the fewer bits remain to represent the fractional part.) This level of precision is useful for mitigating rounding errors in computations, but this advantage only shows if the last few digits are treated as non-significant and thus, ideally, hidden from view. To work with data that is actually this precise – like tracking individual atoms or representing continental drift up to the second –, one must make allowance for these additional non-significant digits and store the coordinates in ''quadruple'' precision.<br />
To track atoms, however, one needs very sensitive (and expensive) equipment with a severely limited range (according to our current understanding of science and technology). Using a global-scale coordinate system when a micrometer-scale would fit much better is either an abuse of the system and a great waste of memory and computing power, or it means that a significant portion of the Earth's surface has been blanketed by quantum microscopes, which would be an abuse and a waste of many other things as well.{{Citation needed}}<br />
|-<br />
| 40<br />
| 1.1 × 10<sup>–11</sup>&nbsp;ym (1.1 × 10<sup>–35</sup>&nbsp;m)<br />
| Near (or past) our current understanding of the nature of distance<br />
| This is where the resolution reaches the Planck length (1.6 × 10<sup>–35</sup>&nbsp;m). At this scale, the very structure of spacetime (and thus, the notion of distance) may be different than what we know; measuring anything to Planck length precision would necessitate such tremendous amounts of energy in one place that would create minuscule black holes, warping spacetime further (in addition to wreaking havoc with whatever you were trying to pinpoint).<br />
|}<br />
<nowiki>*</nowiki>Since the Earth is not exactly spherical, the actual length of one degree of latitude varies between 110.574 km (68.707 mi) at the equator and 111.694 km (69.403 mi) at the poles, while one degree of longitude is 111.320 km (69.171 mi) at the equator, 55.800 km (34.673 mi) at lat. 60°, and 0 km (0 mi) at the poles.<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}}<br />
<br />
[[Category:Space]]<br />
[[Category:Geography]]<br />
[[Category:Programming]]</div>172.68.226.46https://www.explainxkcd.com/wiki/index.php?title=Talk:2185:_Cumulonimbus&diff=177519Talk:2185: Cumulonimbus2019-08-05T18:42:29Z<p>172.68.226.46: </p>
<hr />
<div><!--Please sign your posts with ~~~~ and don't delete this text. New comments should be added at the bottom.--><br />
Hey, the back arrow here doesn't go back to yesterday's "Disappearing Sunday Update" [[Special:Contributions/162.158.75.28|162.158.75.28]] 18:17, 5 August 2019 (UTC)<br />
That's why it was disappearing. [[Special:Contributions/172.68.226.46|172.68.226.46]] 18:42, 5 August 2019 (UTC)</div>172.68.226.46https://www.explainxkcd.com/wiki/index.php?title=2180:_Spreadsheets&diff=1771042180: Spreadsheets2019-07-26T07:47:28Z<p>172.68.226.46: Make 'easy' bold.</p>
<hr />
<div>{{comic<br />
| number = 2180<br />
| date = July 24, 2019<br />
| title = Spreadsheets<br />
| image = spreadsheets.png<br />
| titletext = My brother once asked me if there was a function to produce a calendar grid from a list of dates in Google Sheets. I replied with a single-cell formula that took in a list of dates and outputted a calendar. It used SEQUENCE(), REGEXMATCH(), and a double-nested ARRAYFORMULA(), and it locked up the browser for 15 seconds every time it ran. I think he learned a lot about asking me things.<br />
}}<br />
<br />
==Explanation==<br />
{{incomplete|Created by a REGEXREPLACE(). Need to explain the Google Sheets fucntions. Do NOT delete this tag too soon.}}<br />
Cueball is doing some task on his computer, with an {{w|Shoulder angel|angel and devil on both sides of him}}, trying to influence his work. The angel is telling him to do things the "right" way, while the devil is telling him to do his work using a {{w|spreadsheet}}, which is considered by professional software engineers to be a shortcut or a hack. <br />
<br />
Spreadsheets are the best and most well-known End-user development tool [https://en.wikipedia.org/wiki/End-user_development], allowing non-developers to easily create code with the right specifications fast and with low effort, but they are often mocked by developers as a wrong approach to programming, for its lack of maintainability. Although it is not clear from the cartoon that this is meant, the "right" alternative to using a spreadsheet for some task usually involves a database and a general programming language.<br />
<br />
The punch line comes when the angel becomes so intrigued by the functions that can be accomplished by spreadsheets, Google Sheets in particular, that it gives up trying to dissuade Cueball, and asks for more information from the devil.<br />
<br />
In the title text, Randall mentions a time when he created a calendar grid in Google Sheets using a list of dates. This is described as being done in a "single-cell formula", and taking a long time to run. This shows the power and complexity of spreadsheets. The procedure taking a long time to run, and freezing up the computer for 15 seconds every time it ran, was probably not what Randall's brother had in mind when he requested help. His brother learned he might need to be wary about what he gets back when asking Randall for assistance.<br />
<br />
All functions mentioned in this comic can be found in {{w|Google Sheets}}, but similar functions to some of them can be found in most modern spreadsheet applications.<br />
<br />
REGEXREPLACE(text, regular_expression, replacement)<br />
<br />
ARRAYFORMULA(array_formula)<br />
<br />
QUERY(data, query, [headers])<br />
<br />
IMPORTHTML(url, query, index)<br />
<br />
SEQUENCE(rows, columns, start, step)<br />
<br />
REGEXMATCH(text, regular_expression)<br />
<br />
==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
<br />
[Cueball is at his computer. In the air on either side of him are an angel version of Cueball, with a halo and wings, and a devil version of Cueball, with horns and a pitchfork.]<br />
[The angel's dialogue appears in regular print, while the devil's dialogue appears in white print in black speech balloons.]<br />
:Angel: Don't use a spreadsheet! Do it '''''right'''''.<br />
:Devil: But a spreadsheet would be so '''''easy'''''.<br />
:Angel: In the long run you'll regret it!<br />
<br />
[Closeup on Cueball, the angel, and the devil.]<br />
:Angel: Take the time to write ''real'' code.<br />
:Devil: Just paste the data! Tinker until it works!<br />
:Devil: Build a labyrinth of REGEXREPLACE() and ARRAYFORMULA()!<br />
:Devil: ''Feel the power!''<br />
<br />
[Closeup on the devil.]<br />
:Angel (off-panel): Fight the temptation!<br />
:Devil: Ever tried QUERY() in Google Sheets? It lets you treat a block of cells like a database and run SQL queries on them.<br />
<br />
[Another shot of Cueball at his computer with the angel and devil at either side.]<br />
:Angel: Don't listen to--<br />
:Angel: ... wait, really?<br />
:Devil: Yes, and let me tell you about IMPORTHTML() ...<br />
:Angel: ''Oooh...''<br />
<br />
{{comic discussion}}<br />
[[Category:Comics featuring Cueball]]<br />
[[Category:Computers]]</div>172.68.226.46https://www.explainxkcd.com/wiki/index.php?title=Talk:1885:_Ensemble_Model&diff=145061Talk:1885: Ensemble Model2017-09-07T12:36:32Z<p>172.68.226.46: update of dog speed comment</p>
<hr />
<div><!--Please sign your posts with ~~~~ and don't delete this text. New comments should be added at the bottom.--><br />
<br />
Where's the guy who knows how to make tables? A table would be good for this article, so we could explain each joke scenario. [[Special:Contributions/172.68.26.5|172.68.26.5]] 15:41, 4 September 2017 (UTC)<br />
:I don't like tables when the text in the data cells is more than only a few words. That's bad layout. I have entered all the text from the list into separate headers for the appropriate floating text layout.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 18:39, 4 September 2017 (UTC)<br />
Might be worth mentioning the context for this comic; viz. the approach of hurricane Irma, with a wide range of predictions as to where it might end up (and which areas it would hit), making weather modeling (and hurricane modeling in particular) &ndash; and the uncertainties involved &ndash; topical. It's clear to us now, but won't be clear to readers a few years from now. [[User:Pelosujamo|Pelosujamo]] ([[User talk:Pelosujamo|talk]]) 01:37, 5 September 2017 (UTC)<br />
:Wait - you mean it's not related to Harvey? (In other words, I'm not part of the "us" you speak about.) -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 02:17, 5 September 2017 (UTC)global warming https://www.explainxkcd.com/wiki/index.php/1885:_Ensemble_Model<br />
::I'm pretty sure this was inspired by Irma, not Harvey, because it's about uncertainty in weather modeling; which has received more attention with Irma than it did with Harvey. By the time America started paying real attention to Harvey the National Hurricane Center already had a very good (and accurate) idea about its future path. By contrast, the uncertainties in the Irma models [http://edition.cnn.com/2017/08/31/us/hurricane-irma-forecast-weather/index.html made CNN's front page] long before Irma was anywhere near populated areas. Also, it would be a bit late for Randall to do a Harvey comic; Harvey was last week's news. (Of course, Harvey did make hurricanes cool again.) [[User:Pelosujamo|Pelosujamo]] ([[User talk:Pelosujamo|talk]]) 13:24, 5 September 2017 (UTC)<br />
<br />
I would say that one the idea of randall is related to point the change climate denier invalid reasoning that despite all scenario of global warning show increase of temperature, the fact that none of each is very likely to be wrong then all are wrong. (The fallacy is in the last then: the reunion of little probability can lead to high confidence or a the reunion of sum of various probable things can lead to absolutely certain ) [[User:Xavier Combelle|Xavier Combelle]] ([[User talk:Xavier Combelle|talk]]) 02:35, 5 September 2017 (UTC)<br />
<br />
I have to disagree with the original explanation (now fixed) that ''"there is no reason to have the locomotion speed of dogs as a parameter"''. Dogs are known to chase cats, cats kill a large number of birds, birds eat insects including butterflies. If dogs would run slightly faster there could be a significant variation in the amplitude of the [https://en.wikipedia.org/wiki/Butterfly_effect Butterfly effect]. --[[Special:Contributions/141.101.69.147|141.101.69.147]] 12:13, 5 September 2017 (UTC)<br />
:Besides, the running speed of dogs would presumably impact how often, and where, one would experience raining cats and dogs.[[Special:Contributions/162.158.155.32|162.158.155.32]] 15:30, 6 September 2017 (UTC)<br />
"[one extra cloud in the Bahamas] is most likely too specific and subtle a difference to be useful to the model." - Doesn't that depend on the size and disposition of said cloud? I'd say the problem here is vagueness, rather than insignificance.[[Special:Contributions/162.158.155.32|162.158.155.32]] 15:35, 6 September 2017 (UTC)<br />
<br />
<br />
The upper graph looks like one plotting global temperatures with time using different scenarios, like this one: https://www.ipcc.ch/publications_and_data/ar4/wg1/en/figure-spm-5.html". I do not think this is an appropriate example of an ensemble model. The several trajectories for global temperature are for different policy decisions. In an ensemble model various trajectories reflect uncertainty about are a result of uncertainty about initial conditions or the physical rules that control the evolution of the system. TLDR: A map is not an ensemble model.<br />
The uncertainty (shaded area) for each track may or may not be the result of an ensemble, but if it is an ensemble for one of the scenarios would be a better example.<br />
Also ensembles are typically used for non-linear, chaotic systems and this should probably be somewhere in the explanation. <br />
[[Special:Contributions/162.158.62.159|162.158.62.159]] 17:06, 6 September 2017 (UTC)</div>172.68.226.46