explain xkcd - User contributions [en]

1916: Temperature Preferences

2017-11-16T02:51:44Z

108.162.238.173: added Raleigh (NC State) (not sure how to find dew point)

{{comic
| number = 1916
| date = November 15, 2017
| title = Temperature Preferences
| image = temperature_preferences.png
| titletext = There's a supposed Mark Twain quote, "The coldest winter I ever spent was a summer in San Francisco." It isn't really by Mark Twain, but I don't know who said it—I just know they've never been to McMurdo Station.
}}

==Explanation==
{{incomplete|Fill in the table using data from [http://weatherbase.com weatherbase.com] (Randall's source!). Do NOT delete this tag too soon.}}
This is a chart of major (and not-so-major) populated areas showing seasonal temperature patterns. The chart is a guide to where one might like to live depending on how much summer heat and winter cold they enjoy. There are four focused zones:

* Hate both cold and heat (eg. Quito, Addis Ababa)--Neither summers nor winters are too extreme
* Hate cold but love heat (eg. Rio, Bangkok, Manila)--Very hot in the summer; typically tropical regions
* Hate heat but love cold (eg. Moscow, Oslo)--Very cold in the winter; typically high latitudes
* Love both heat and cold (eg. Seoul, Beijing)--Both summers and winters are extreme

The summer heat axis is determined by {{w|humidex}}, a system that combines heat and humidity to generate an estimate of perceived "summer discomfort".

{| class="wikitable sortable"
! City
! Country
! Continent
! Average low in coldest month (°C)
! Average high in hottest month (°C)
! Hottest monthly average dew point (°C)
! Humidex
! Latitude
! Elevation (m)
|-
| {{w|Abakan}} || Russia || Asia || -22 || 26 || 13 || 28.8 || 53° 43′ N ||
|-
| {{w|Addis Ababa}} || Ethiopia || Africa || 10 || 22 || 11 || 23.8 || 9° 1′ N || 2355
|-
| {{w|Altay City|Altay}} || China || Asia || -22 || 27 || 8 || 27.4 || 47° 52′ N || 887
|-
| {{w|Athens}} || Greece || Europe || 7 || 31.8 || 14 || 35.2 || 37° 59′ N || 70
|-
| {{w|Atlanta}} || United States || North America || 1.3 || 31.7 || 20.1 || 39.4 || 33° 45′ N || 225
|-
| {{w|Baghdad}} || Iraq || Asia || 3 || 43 || 8 || 43.4 || 33° 20′ N || 34
|-
| {{w|Bangkok}} || Thailand || Asia || 21 || 34 || 24 || 45.3 || 13° 45′ N || 1.5
|-
| {{w|Barcelona}} || Spain || Europe || 4.4 || 28 || 18 || 34 || 41° 23′ N || 12
|-
| {{w|Beijing}} || China || Asia || -8 || 30 || 20 || 37.6 || 39° 55′ N || 43.5
|-
| {{w|Berlin}} || Germany || Europe || -3 || 22 || 11 || 23.8 || 53° 31′ N || 34
|-
| {{w|Blagoveshchensk}} || Russia || Asia || -26.2 || 27.3 || 16 || 31.9 || 50° 15′ N ||
|-
| {{w|Bogotá}} || Colombia || South America || 6 || 19 || 10 || 20.3 || 4° 42′ N || 2640
|-
| {{w|Boston}} || United States || North America || -5.4 || 27.6 || 16.3 || 32.4 || 42° 21′ N || 43
|-
| {{w|Brisbane}} || Australia || Oceania || 9 || 28 || 18 || 34 || 27° 28′ S || 28
|-
| {{w|Budapest}} || Hungary || Europe || -3 || 26 || 12 || 28.3 || ° ′ N ||
|-
| {{w|Buenos Aires}} || Argentina || South America || 7.4 || 30.4 || 16 || 35 || ° ′ N ||
|-
| {{w|Cairo}} || Egypt || Africa || 9 || 33 || 18 || 39 || ° ′ N ||
|-
| {{w|Calgary}} || Canada || North America || -13.2 || 23.2 || 7 || 23.2 || ° ′ N ||
|-
| {{w|Cape Town}} || South Africa || Africa || 8 || 25 || 15 || 29 || ° ′ N ||
|-
| {{w|Casper, Wyoming|Casper}} || United States || North America || -10.3 || 31.2 || 6.8 || 31.1 || ° ′ N ||
|-
| {{w|Chengdu}} || China || Asia || 2 || 28 || 22 || 37.3 || ° ′ N ||
|-
| {{w|Dallas}} || United States || North America || 3 || 36 || 19.4 || 43.1 || ° ′ N ||
|-
| {{w|Da Qaidam}} || China || Asia || -23 || 22 || -6 || 18.6 || ° ′ N ||
|-
| {{w|Dar es Salaam}} || Tanzania || Africa || 19 || 31 || 23 || 41.3 || ° ′ N ||
|-
| {{w|Washington, D.C.|DC}} || United States || North America || -1.9 || 31.3 || 19.1 || 38.1 || ° ′ N ||
|-
| {{w|Delhi}} || India || Asia || 7.8 || 39.8 || 24 || 51.1 || ° ′ N ||
|-
| {{w|Dhaka}} || Bangladesh || Asia || 12.7 || 33.7 || 25 || 46 || ° ′ N ||
|-
| {{w|Dubai}} || United Arab Emirates || Asia || 14 || 39 || 23 || 49.3 || ° ′ N ||
|-
| {{w|Dublin}} || Ireland || Europe || 2.3 || 19.5 || 11 || 21.3 || ° ′ N ||
|-
| {{w|Duluth}} || United States || North America || -16.1 || 23.4 || 13.3 || 26.4 || ° ′ N ||
|-
| {{w|Edinburgh}} || United Kingdom || Europe || 1.1 || 19.2 || 10 || 20.5 || ° ′ N ||
|-
| {{w|El Paso}} || United States || North America || -0.3 || 35.6 || 12.8 || 38.3 || ° ′ N ||
|-
| {{w|Fairbanks}} || United States || North America || -27.2 || 22.6 || 9.8 || 23.8 || ° ′ N ||
|-
| {{w|Fargo, North Dakota|Fargo}} || United States || North America || -17.7 || 28.1 || 15.1 || 32.1 || ° ′ N ||
|-
| {{w|Flagstaff, Arizona|Flagstaff}} || United States || North America || -7.3 || 30.9 || 8.2 || 31.4 || ° ′ N ||
|-
| {{w|Geneva}} || Switzerland || Europe || -1.3 || 26.5 || 12 || 28.8 || ° ′ N ||
|-
| {{w|Guangzhou}} || China || Asia || 10 || 32 || 25 || 44.3 || ° ′ N ||
|-
| {{w|Hailar District|Hailar}} || China || Asia || -32 || 25 || 13 || 27.8 || ° ′ N ||
|-
| {{w|Halifax, Nova Scotia|Halifax}} || Canada || North America || -10 || 22 || 13 || 24.8 || ° ′ N ||
|-
| {{w|Ho Chi Minh City}} || Vietnam || Asia || 22 || 33 || 23 || 43.3 || ° ′ N ||
|-
| {{w|Hong Kong}} || China || Asia || 14 || 31 || 24 || 42.3 || ° ′ N ||
|-
| {{w|Honolulu}} || United States || North America || 18.9 || 31.1 || 20.1 || 38.8 || ° ′ N ||
|-
| {{w|Houston}} || United States || North America || 6.2 || 34.7 || 22.7 || 44.7 || ° ′ N ||
|-
| {{w|Irkutsk}} || Russia || Asia || -22 || 24.8 || 12 || 27.1 || ° ′ N ||
|-
| {{w|Istanbul}} || Turkey || Europe* || 2 || 27 || 16 || 31.6 || ° ′ N ||
|-
| {{w|Jakarta}} || Indonesia || Asia || 23 || 31 || 23 || 41.3 || ° ′ N ||
|-
| {{w|Jerusalem}} || Israel || Asia || 6.4 || 29.4 || 15 || 33.4 || ° ′ N ||
|-
| {{w|Jinzhou}} || China || Asia || -12 || 27 || 20 || 34.6 || ° ′ N ||
|-
| {{w|Kabul}} || Afghanistan || Asia || -5 || 31 || 8 || 31.4 || ° ′ N ||
|-
| {{w|Kansas City}} || United States || North America || -6.9 || 31.3 || 19.6 || 38.5 || ° ′ N ||
|-
| {{w|Karachi}} || Pakistan || Asia || 12 || 33 || 25 || 45.3 || ° ′ N ||
|-
| {{w|Kiev}} || Ukraine || Europe || -9 || 23 || 12 || 25.3 || ° ′ N ||
|-
| {{w|Kinshasa}} || Democratic<br> Republic of Congo || Africa || 20 || 30 || 21 || 38.4 || ° ′ N ||
|-
| {{w|Lagos}} || Nigeria || Africa || 23 || 30 || 23 || || ° ′ N ||
|-
| {{w|Lahore}} || Pakistan || Asia || 8|| 38 || 24 || 40.3 || ° ′ N ||
|-
| {{w|London}} || United Kingdom || Europe || 1 || 22.9 || 12 || 49.3 || ° ′ N ||
|-
| {{w|Los Angeles}} || United States || North America || 13 || 22 || 16.2 || 25.2 || ° ′ N ||
|-
| {{w|Lubbock}} || United States || North America || -3.6 || 33.8 || 15.9 || 26.7 || ° ′ N ||
|-
| {{w|Madrid}} || Spain || Europe || 2.6 || 31.2 || 11 || 38.3 || ° ′ N ||
|-
| {{w|Manila}} || Philippines || Asia || 21 || 33 || 23 || 33 || ° ′ N ||
|-
| {{w|McMurdo Station|McMurdo}} || || Antarctica || -31 || -1 || -8 || 43.3 || ° ′ N ||
|-
| {{w|Melbourne}} || Australia || Oceania || || || || -4.7 || ° ′ N ||
|-
| {{w|Mexico City}} || Mexico || North America || || || || || ° ′ N ||
|-
| {{w|Miami}} || United States || North America || || || || || ° ′ N ||
|-
| {{w|Minneapolis}} || United States || North America || || || || || ° ′ N ||
|-
| {{w|Moscow}} || Russia || Europe || || || || || ° ′ N ||
|-
| {{w|Mumbai}} || India || Asia || || || || || ° ′ N ||
|-
| {{w|Nairobi}} || Kenya || Africa || || || || || ° ′ N ||
|-
| {{w|Needles, California|Needles}} || United States || North America || || || || || ° ′ N ||
|-
| {{w|Omaha}} || United States || North America || || || || || ° ′ N ||
|-
| {{w|Oslo}} || Norway || Europe || || || || || ° ′ N ||
|-
| {{w|Ottawa}} || Canada || North America || || || || || ° ′ N ||
|-
| {{w|Paris}} || France || Europe || 2.7 || 25.2 || 12 || || ° ′ N ||
|-
| {{w|Perth}} || Australia || Oceania || || || || 27.5 || ° ′ N ||
|-
| {{w|Portland, Oregon|Portland}} || United States || North America || || || || || ° ′ N ||
|-
| {{w|Pyongyang}} || North Korea || Asia || || || || || ° ′ N ||
|-
| {{w|Qiqihar}} || China || Asia || || || || || ° ′ N ||
|-
| {{w|Quito}} || Ecuador || South America || 9 || 20 || 9 || || ° ′ N ||
|-
| {{w|Raleigh}} || United States || North America || 50 || 70.7 || || 20.8 || 35° 47′ N || 119
|-
| {{w|Regina, Saskatchewan|Regina}} || Canada || North America || || || || || ° ′ N ||
|-
| {{w|Reykjavik}} || Iceland || Europe || -2 || 12 || 7 || || ° ′ N ||
|-
| {{w|Richmond, Virginia|Richmond}} || United States || North America || || || || 12 || ° ′ N ||
|-
| {{w|Rio de Janeiro|Rio}} || Brazil || South America || 16.9 || 32.9 || 21 || 48 || 22° 49′ S || 6
|-
| {{w|Riyadh}} || Saudi Arabia || Asia || || || || || ° ′ N ||
|-
| {{w|Rome}} || Italy || Europe || || || || || ° ′ N ||
|-
| {{w|Sabha, Libya|Sabha}} || Libya || Africa || || || || || ° ′ N ||
|-
| {{w|St. Louis|Saint Louis}} || United States || North America || || || || || ° ′ N ||
|-
| {{w|Salt Lake City}} || United States || North America || -5.8 || 33.7 || 7.7 || 38 || 40° 47′ N || 1286
|-
| {{w|San Francisco}} || United States || North America || || || || || ° ′ N ||
|-
| {{w|Santa Fe, New Mexico|Santa Fe}} || United States || North America || || || || || ° ′ N ||
|-
| {{w|Santiago}} || Chile || South America || 2.5 || 29.4 || || || ° ′ N ||
|-
| {{w|Sao Paulo}} || Brazil || South America || 12 || 28 || 18 || 39 || 23° 37′ S || 802
|-
| {{w|Sapporo}} || Japan || Asia || || || || || ° ′ N ||
|-
| {{w|Seoul}} || South Korea || Asia || || || || || ° ′ N ||
|-
| {{w|Shanghai}} || China || Asia || || || || || ° ′ N ||
|-
| {{w|Shenyang}} || China || Asia || || || || || ° ′ N ||
|-
| {{w|Singapore}} || Singapore || Asia || || || || || ° ′ N ||
|-
| {{w|Sioux Falls}} || United States || North America || || || || || ° ′ N ||
|-
| {{w|St Petersburg}} || Russia || Europe|| || || || || ° ′ N ||
|-
| {{w|Stockholm}} || Sweden || Europe || || || || || ° ′ N ||
|-
| {{w|Sydney}} || Australia || Oceania || || || || || ° ′ N ||
|-
| {{w|Tashkent}} || Uzbekistan || Asia || || || || || ° ′ N ||
|-
| {{w|Tehran}} || Iran || Asia || || || || || ° ′ N ||
|-
| {{w|Thunder Bay}} || Canada || North America || || || || || ° ′ N ||
|-
| {{w|Tokyo}} || Japan || Asia || || || || || ° ′ N ||
|-
| {{w|Tongliao}} || China || Asia || || || || || ° ′ N ||
|-
| {{w|Toronto}} || Canada || North America || || || || || ° ′ N ||
|-
| {{w|Turpan}} || China || Asia || || || || || ° ′ N ||
|-
| {{w|Ulaanbaatar}} || Mongolia || Asia || || || || || ° ′ N ||
|-
| {{w|Urumqi}} || China || Asia || || || || || ° ′ N ||
|-
| {{w|Vancouver}} || Canada || North America || || || || || ° ′ N ||
|-
| {{w|Vladivostok}} || Russia || Asia || || || || || ° ′ N ||
|-
| {{w|Volgograd}} || Russia || Europe|| || || || || ° ′ N ||
|-
| {{w|Wellington}} || New Zealand || Oceania || || || || || ° ′ N ||
|-
| {{w|Wuhan}} || China || Asia || || || || || ° ′ N ||
|-
| {{w|Xi'an}} || China || Asia || || || || || ° ′ N ||
|-
| {{w|Yellowknife}} || Canada || North America || -29.5 || 21.3 || 7 || || ° ′ N ||
|-
| {{w|Yumen City|Yumen}} || China || Asia || || || || 21.3 || ° ′ N ||
|-
|}
*Istanbul spans both Europe and Asia but its city center is located in Europe.

==Transcript==
:[A chart labeled:]
:<big>Where to live</big>
:based on your temperature preferences
:[In gray, the data source is mentioned below:]
:Climate data from [http://weatherbase.com weatherbase.com]

:[A chart with two lines with single arrows. Each arrow is labeled:]
:Y axis bottom: Cold winters
:X axis right: Hot/humid summers (measured via Humidex, which combines heat and dew point)

:[Near each of the corners of the chart there is a gray blob, labeled:]
:Top left: If you hate cold and heat
:Top right: If you hate cold and love heat
:Bottom left: If you love cold and hate heat
:Bottom right: If you love cold and heat

:[The following city names intersect with the top left blob [hate cold and heat] (in reading order):]
:Mexico City
:Quito
:Addis Ababa
:Bogotá
:San Francisco
:Wellington

:[The following city names intersect with the top right blob [hate cold and love heat] (in reading order):]
:Bangkok
:Ho Chi Minh City
:Manila
:Singapore
:Mumbai
:Jakarta
:Dar Es Salaam
:Honolulu
:Lagos
:Rio [de Janeiro]
:Dhaka
:Kinhasa
:Miami
:Karachi
:Dubai
:Cairo
:Hong Kong
:Delhi
:Riyadh
:Guangzhou
:Lahore
:Sabha
:Houston
:Needles
:El Paso
:Baghdad
:Dallas

:[The following city names intersect with the bottom left blob [love cold and hate heat] (in reading order):]
:Reykjavik (with arrow pointing left)
:Berlin
:Stockholm
:Oslo
:Calgary
:Halifax
:Daqaidam
:Kiev
:Casper
:Yumen
:St Petersburg
:Volgograd
:Moscow
:Ottawa
:Vladivostok
:Thunder Bay
:Duluth
:Urumqi
:Altay
:Regina
:Irkutsk
:Abakan
:Ulaanbaatar
:Blagoveshchensk (also on bottom right blob)
:Fairbanks
:McMurdo (with arrow pointing down-left)
:Yellowknife (with arrow pointing down)
:Hailar

:[The following city names intersect with the bottom right blob [love cold and heat] (in reading order):]
:[Washington] DC
:Shanghai
:Tehran
:Saint Louis
:New York
:Xi'An
:Salt Lake City
:Kansas City
:Beijing
:Seoul
:Sapporo
:Pyongyang
:Sioux Falls
:Turpan
:Jinzhou
:Minneapolis
:Shenyang
:Fargo
:Tongliao
:Qiqihar
:Blagoveshchensk (also on bottom left blob)

:[The following city names do not intersect with any blob (in reading order):]
:Nairobi
:São Paulo
:Brisbane
:Los Angeles
:Perth
:Cape Town
:Sydney
:Athens
:Santiago
:Barcelona
:Melbourne
:Rome
:Buenos Aires
:Jerusalem
:Atlanta
:Raleigh
:Madrid
:Chengdu
:Tokyo
:Dublin
:Portland
:Richmond
:London
:Istanbul
:Edinburgh
:Vancouver
:Paris
:Flagstaff
:Santa Fe
:Tashkent
:Wuhan
:Geneva
:Lubbock
:Boston
:Budapest
:Kabul
:Toronto
:Omaha

{{comic discussion}}

[[Category:Scatter plots]]

1901: Logical

2017-10-11T16:09:28Z

108.162.238.173: /* Explanation */ missing "not"

{{comic
| number = 1901
| date = October 11, 2017
| title = Logical
| image = logical.png
| titletext = It's like I've always said--people just need more common sense. But not the kind of common sense that lets them figure out that they're being condescended to by someone who thinks they're stupid, because then I'll be in trouble.
}}

==Explanation==
{{incomplete|Needs more.}}

White Hat says that problems in society could be avoided if people relied on logic and science rather than feelings -- but when Cueball asks him what study he is relying to prove that, White Hat has no study to prove that and relies on his own feelings, without realizing that he himself is doing what he just denounced.

The title text is White Hat's opinion, where he says that people need more common sense, but not enough to have them know when he is talking down to them.

==Transcript==

:White Hat: We wouldn't have all these problems if people just learned to be more ''logical'' and ''science-driven'' instead of relying on ''feelings''.
:Cueball: Oh? What study are you basing that on?
:White Hat: It just seems obvious!
:White Hat: I mean, look at the crap these idiots believe!

:Title Text: It's like I've always said--people just need more common sense. But not the kind of common sense that lets them figure out that they're being condescended to by someone who thinks they're stupid, because then I'll be in trouble.

{{comic discussion}}

1134: Logic Boat

2017-10-11T14:29:34Z

108.162.238.173: /* Explanation */

{{comic
| number = 1134
| date = November 14, 2012
| title = Logic Boat
| image = logic boat.png
| titletext = Or a cabbage, for that matter. Goats make sense. Goats are fine.
}}

==Explanation==
The comic is a play on the classic {{w|wolf, goat and cabbage puzzle}} belonging to the {{w|river crossing puzzle}}s, and first known from {{w|Propositiones ad Acuendos Juvenes}}, with the same setting as here. The three possessions change between various retellings but it typically involves a {{w|Carnivore|carnivorous animal}} (wolf, lion etc.), a {{w|herbivore}} (goat, sheep, chicken, goose etc.), and some plant based food (cabbage, grain, beans etc.). The objective {{tvtropes|FoxChickenGrainPuzzle|is to ferry all three possessions to the other side of a river safely in a small boat}}, with the limitation of only being able to transport one possession per crossing. The crossing order must take into account that the carnivore would eat the herbivore if left alone together, and the herbivore would eat the food.

The traditional solution would be:

{| class="wikitable"
|-
! Origin
! Destination
|-
| Cueball, Wolf, Goat, Cabbage
|
|-
| colspan="2" align="center" style="background: #ffdead;" | Trip 1: Take goat across
|-
| Wolf, Cabbage
| Cueball, Goat
|-
| colspan="2" align="center" style="background: #ffdead;" | Trip 2: Return alone
|-
| Cueball, Wolf, Cabbage
| Goat
|-
| colspan="2" align="center" style="background: #ffdead;" | Trip 3: Take cabbage across
|-
| Wolf
| Cueball, Goat, Cabbage
|-
| colspan="2" align="center" style="background: #ffdead;" | Trip 4: Return with goat
|-
| Cueball, Wolf, Goat
| Cabbage
|-
| colspan="2" align="center" style="background: #ffdead;" | Trip 5: Take wolf across
|-
| Goat
| Cueball, Wolf, Cabbage
|-
| colspan="2" align="center" style="background: #ffdead;" | Trip 6: Return alone
|-
| Cueball, Goat
| Wolf, Cabbage
|-
| colspan="2" align="center" style="background: #ffdead;" | Trip 7: Take goat across
|-
|
| Cueball, Wolf, Goat, Cabbage
|}

(Note that, since the conditions for this problem are symmetric, an alternate solution would be to transport the wolf on Trip 3 and the cabbage on Trip 5.)

By leaving the wolf behind, four steps are saved — the comic's "step 4" is just a comment — and the troublesome wolf, a wild and dangerous animal not usually kept by humans, is eliminated from the picture.

This could be seen a jab on the common assumption that logic puzzles only have one correct solution. Thus one often keeps the other person thinking and guessing until they arrive at the pre-defined solution, no matter how many other creative good solutions they come up with. Also note that the "problem" given doesn't even state an objective, just three prerequisites.

The title texts says that goats are fine. The same opinion is in [[1282: Monty Hall]].

==Transcript==
:[A person shows up at a boat docked at the edge of a river. The person has brought along a head of cabbage, a goat, and a wolf.]
:Problem: The boat only holds two, but you can't leave the goat with the cabbage or the wolf with the goat.

:[The wolf looks curiously at the cabbage that's been left behind while the person goes off with the goat.]
:Solution: 1. Take the goat across.

:[The goat remains tied up on the far side. The wolf watches the person come back.]
:2. Return alone.

:[The wolf sits and waits as the person goes off.]
:3. Take the cabbage across.

:4. Leave the wolf. Why did you have a wolf?
:[The wolf goes off.]

{{comic discussion}}
[[Category:Comics featuring Cueball]]
[[Category:Logic]]
[[Category:Animals]]

1537: Types

2015-06-13T17:52:15Z

108.162.238.173: Continuation of NaP

{{comic
| number = 1537
| date = June 12, 2015
| title = Types
| image = types.png
| titletext = colors.rgb("blue") yields "#0000FF". colors.rgb("yellowish blue") yields NaN. colors.sort() yields "rainbow"
}}

==Explanation==
{{incomplete|Title text not explained. More details before the list.}}

This comic is a series of programming jokes about a ridiculous new programming language, perhaps inspired by [https://www.destroyallsoftware.com/talks/wat Gary Bernhardt's CodeMash 2012 lightning talk] on JavaScript's unpredictable typing. In the talk, the (highly technical) audience was unable to correctly guess the results of adding various JavaScript types and roared with laughter when they were revealed. The programming language shown in this comic has types even more unpredictable than JavaScript.

Most regular programming languages distinguish a number of types, e.g. integers, strings, lists… all of which have different behaviours. The operation "+" is usually conventionally defined over more than one of these types. Applied to two integers, it returns their sum. Applied to two strings (denoted by being enclosed in quotes) it concatenates them:

<code>> 2 + 3

5

> "123" + "abc"

"123abc"</code>

While these behaviours are standard, conventional, and intuitive, there is a huge amount of variation among programming languages when you apply an operation like "+" to different types. One logical approach is to always return an error in all cases of type mixing, but it is often practical to allow some case mixing, since it can hugely simplify expressions. Variation and lack of a clearly more intuitive behaviour leads some languages to have weird results when you mix types.

# <code>2 + "2"</code> uses the <code>+</code> operator on a number and a string. In some programming languages, this might result in the number <code>4</code> (addition), or <code>"22"</code> (string concatenation); however, the new language converts the string to an integer, adds them to produce <code>4</code> and converts back to a string. Alternately, it may instead be adding 2 to the ASCII value of the character <code>"2"</code> (50), resulting in the character <code>"4"</code> (52). This is (somewhat) consistent with the behavior for item 4.
# <code>"2" + []</code> adds a string to an array or list. This first inexplicably converts the string to a number again, and then it literally adds the number to the list by appending it (this would make sense if it was <code>[] + 2</code>, but usually not the other way around). And then the result (the entire array) is converted to a string again.
# <code>(2/0)</code> divides <code>2</code> by <code>0</code> and quite reasonably results in <code>NaN</code> (not a number), though in most languages, as prescribed by the IEEE 854 standard for floating point numbers, dividing a nonzero number by zero would instead return an infinity value.
# <code>(2/0)+2</code> adds <code>2</code> to <code>NaN</code>. <code>2</code> is "added" to the string <code>"NaN"</code> (again, the number is converted to a string for apparently no reason), which produces <code>"NaP"</code>. If the language's convention is to add to the ASCII value of a character or string, then in this case it added 2 to the character <code>"N"</code> (78), resulting in <code>"P"</code> (80). How the string "NaP" is converted into a bare NaP with undefined meaning is not clear.
# <code>""+""</code>: In many languages, two consecutive double-quote characters denote an empty string, so this expression would concatenate two empty strings, resulting in an empty string. However, it appears that this language treats only the outermost quotes of the expression as the string boundary, so all of the characters between them become part of the literal string, producing '<code>"+"</code>' (In many programming languages, you can use both <code>"</code> or <code>'</code> to delimit strings and both behave similar if not identical).
# <code>[1,2,3]+2</code> seems to test whether it's sound to append <code>2</code> to the list <code>[1,2,3]</code>, and concludes that it doesn't fit the pattern, returning the boolean value <code>false</code>. It could conceivably also be the result of an attempt to add <code>2</code> to the ''set'' <code>[1,2,3]</code>, which already contains that element (although <code>{1,2,3}</code> would be a more common notation for sets).
# <code>[1,2,3]+4</code> returns <code>true</code> for much the same reason.
# <code>2/(2-(3/2+1/2))</code> is a floating point joke. Floating point numbers are notoriously imprecise. With precise mathematics, <code>(3/2+1/2)</code> would be exactly 2, hence the entire thing would evaluate to <code>2/0</code> or <code>NaN</code> in Randall's new language. However, the result of <code>(3/2+1/2)</code> is "just slightly off," which makes the result "just slightly off" of <code>NaN</code>, which would be ridiculous in a real language. The ironic thing is that fractions with 2 in the denominator are ''not'' the kind of numbers that typically suffer from floating point impreciseness. Additionally, if there was indeed a rounding error, the actual calculation becomes something like <code>2/0.0000000000000013</code>, which should not return a <code>NaN</code> since it is not division by zero.
# <code>range(" ")</code> normally wouldn't make any sense. However, the new language appears to interpret it as ASCII, and in the ASCII table, character #32 is space, #33 is <code>!</code>, and #34 is <code>"</code>. So, instead of interpreting <code>" "</code> as a string, it seems to be interpreted as <code>34, 32, 34</code> (in ASCII), and then <code>range</code> appears to transform this into <code>34, 33, 32, 33, 34</code> (the "ranges" between the numbers), which, interpreted as ASCII, becomes <code>['"', '!', ' ', '!', '"']</code>.
# <code>+2</code> is "simply" attempting to add 2 to the line number 10 to get 12. Alternately, it could refer to the Chinese/Japanese (Kanji) number system, where the plus sign is instead the symbol <code>十</code>. In Chinese, this symbol represents the number ten, and if you translate the <code>2</code> into Chinese, you get <code>二</code>. Therefore, in full Chinese the code is <code>十二</code>, which is equivalent to the number <code>12</code>.
# <code>2+2</code> would normally be <code>4</code>. However, the interpreter takes this instruction to mean that the user wishes to increase the actual value of the number <code>2</code> (aka the "literal value") by <code>2</code> for the remainder of the program, making it <code>4</code> and then reports that the work is "Done". The result can be seen in the subsequent lines where all <code>2</code>s are replaced by <code>4</code>s. This could be a reference to languages like Fortran where [http://everything2.com/title/Changing+the+value+of+5+in+FORTRAN literals could be assigned new values].
# <code>range(1,5)</code> would normally return <code>[1, 2, 3, 4, 5]</code>. However, since the value of <code>2</code> has been changed to <code>4</code>, it returns <code>[1, 4, 3, 4, 5]</code>, and this even affects the line number (which is 14 instead of 12).
# <code>floor(10.5)</code> should return <code>10</code> (the "floor" of a decimal number is that number rounded down). However, it instead returns {{w|ASCII art}} of the number on a "floor."

The title text contains three further examples relating to color. <code>color.rgb("blue")</code> returns the hexadecimal code for pure blue (as would be used in HTML, for example), which is how a real programming language might work. The lookup for "yellowish blue" returns "NaN" (Not a Number) again, which makes sense at one level because there is no such color as "yellowish blue" (yellow and blue are opposites on the color wheel, making yellowish-blue an {{w|impossible colour}}, which can only be perceived with great difficulty through contrived figures). However a more typical result would have been a failure indicating that the color database does not include the name, in the same way that a typo such as "bluw" would. Similarly sorting the colors would normally produce some defined ordering, such as alphabetical, but in this language it generates the string "rainbow". It seems that Randall's new language understands color theory in an unusually deep way.

==Transcript==
My new language is great, but it has a few quirks regarding type:
<pre>
[1]> 2+"2"
=> "4"
[2]> "2"+[]
=> "[2]"
[3] (2/0)
=> NaN
[4]> (2/0)+2
=> NaP
[5]> ""+""
=> '"+"'
[6]> [1,2,3]+2
=> FALSE
[7]> [1,2,3]+4
=> TRUE
[8]> 2/(2-(3/2+1/2))
=> NaN.0000000000000013
[9]> range(" ")
=> ('"','!'," ","!",'"')
[10]> +2
=> 12
[11]> 2+2
=> DONE
[14]> RANGE(1,5)
=> (1,4,3,4,5)
[13]> FLOOR(10.5)
=> |
=> |
=> |
=> |___10.5___
</pre>
{{comic discussion}}
[[Category:Programming]]
[[Category:Language]]

1474: Screws

2015-01-16T19:53:59Z

108.162.238.173: /* Explanation */ Removed "idiotic"

{{comic
| number = 1474
| date = January 16, 2015
| title = Screws
| image = screws.png
| titletext = If you encounter a hex bolt, but you only brought screwdrivers, you can try sandwiching the head of the bolt between two parallel screwdriver shafts, squeezing the screwdrivers together with a hand at either end, then twisting. It doesn't work and it's a great way to hurt yourself, but you can try it!
}}

==Explanation==
{{incomplete|May still needs expansion, possibly with origins of the various real screws?}}

The comic features various real or imagined types of screws, listed below.

{| class="wikitable"
! style="width: 25%"|Screw type
! Description
|-
| Phillips head
| {{w|List of screw drives#Phillips|Phillips screw drive}} and its corresponding screw head is one of the most recognizable types of screw heads that is commonly used in construction. This type of screw head was named after its inventor, a US businessman {{w|Henry F. Phillips}}. Neither the inventor nor his invention have any relationship to the Dutch electronics manufacturing company with similar, but not exactly the same name {{w|Philips}}.
|-
| Flat head
| {{w|List_of_screw_drives#Slot|Slot head screws}} are frequently erroneously referred to as flat heads (a flat head screw refers, in fact, to the shape of the screw head, regardless of the shape of the drive socket). The slot head is also commonly used in construction. The diagram shows the slot truncated, while typically the slot almost always runs across the entire head of the screw (as in the case of the "uranium screw" below).
|-
| Uh oh. Maybe it's on Amazon? (star-shaped screw)
| Manufacturers sometimes used screws that require special screwdrivers in order to remove them, in order to prevent the customer tampering with the product. The reference to Amazon is the speaker's suggestion to look on Amazon.com for the appropriate screwdriver. A number of star-shaped screw heads exist, notably the six-pointed {{w|Torx}}, and Apple's rounded {{w|Pentalobe screw|pentalobe screw}}, although there is no popular design that uses the 5-pointed star shape depicted in the comic. Torx screws are common in automotive applications — they are easier to screw in via electric screwdrivers — and on bicycles where a higher tightening torque is needed than hex screws can support. They are also commonly used on disk brake mounts.

|-
| Cursed -1 Phillips head
| The head of a screw can be stripped by overuse, tightening the screw too much, or other misuse. As the driving surfaces wear away, removing the screw becomes more and more difficult, usually damaging the screw more in the process.

The addition of "cursed" and "-1" in the titles is a reference to various fantasy games (E.g. Dungeons and Dragons), where magical "cursed" items appear frequently. This often makes the cursed equipment (in the case of armor or weapons) incredibly difficult to remove, as it will cling to the wielder. Similarly, The cursed Phillips Head screw becomes difficult to remove due to the stripped head.

The "-1" refers to the damage of the screw head. In fantasy games, items such as weapons and armor may have an "enchantment", with a positive enchantment making the item more effective, and a negative enchantment making the item less effective. Negatively enchanted items are often also cursed, as is the case with this screw head. The "-1" does not appear to be a reference to a Philips bit-size number, as those are always positive.

Or, it could just mean a {{w|List_of_screw_drives#Pozidriv|Pozidriv head}}.
|-
| Rivet
| A {{w|rivet}} is not a screw - it is a permanent fastener which is secured by deforming the body of the fastener. Rivets cannot be removed with a screwdriver, they must be "drilled out". Some bolts also have rounded rivet-style heads, though, with no means of gripping them.
|-
| Phillips head ruiner (hex screw)
| A reference to the fact that {{w|List_of_screw_drives#Hex_socket|hex socket}} screws can, in a pinch, be removed with a Phillips screwdriver, but will likely damage the driver in the process. Hex screws are common on bicycles, where they always come in the metric varieties. The same holds for hex screws which ship with Ikea furniture —who bundle a low-quality hex driver for those people who lack them. Imperial-sized hex screws do sometimes surface, to the dissatisfaction of anyone who owns a hex driver set. The smaller hex screws can enter the "-1" state when attempting to unscrew one that has been overtightened —hence the adoption of Torx screws in high-torque applications.

|-
| Uranium screw
| Uranium screws were [http://blog.nuclearsecrecy.com/2014/11/10/fat-mans-uranium/ used] in the [http://www.osti.gov/scitech/biblio-page/769001/8/72 construction] of [http://www.scintillators.ru/booc/criticality/reports/ref_050.pdf nuclear weapons] during the twentieth century.
|-
| Phillip's head
| This is a literal (and rather morbid) interpretation of the misspelling "Phillip's head" when "Phillips head" is meant. Rather than refer to the screw type, this "screw" is actually a bloody bag containing the severed head of someone named Phillip. It could possibly be an allusion to one of the {{w|Decapitation|decapitations}} of the royal persons that took place several times in the human history, perhaps even more specifically to {{w|French Revolution|revolutionary France}} where {{w|Capital punishment|capital punishment}} by decapitation was made well-known due to introduction of {{w|Guillotine|guillotine}} and its active use against the former royalty. However, despite the {{w|Philip|name Phillip being used by several members of the upper echelon of French royalty}}, none of the {{w|List of people who were beheaded|famous people ever executed this way in France or anywhere else}} were called Phillip, although {{w|Louis Philippe II, Duke of Orléans|Philippe Égalité}}, the adopted name of Louis Philippe Joseph d'Orléans, ''was'' guillotined. Intentionally or otherwise, this last punchline could be described as a "mind screw".
|-
|Hex bolt (title text)
|A {{w|List_of_screw_drives#Hex|hex bolt}} has six external sides, so it could in theory be held by squeezing two screwdriver shafts together with the bolt in between. The amount of force on the two screwdriver shafts needed to turn the hex bolt will probably exceed the strength of human hands and would most likely result in hurting your hands and not in turning the bolt.
|}

==Transcript==
:[Eight drawings of different types of heads each with a caption:]
:Phillips head
:Flat head
:Uh oh. Maybe it's on Amazon?
:Cursed –1 Phillips head
:Crap, it's a ''rivet''.
:Phillips-head ruiner
:Uranium screw (a real thing)
:Phillip's head

{{comic discussion}}

Talk:1340: Unique Date

2014-10-01T04:02:31Z

108.162.238.173:

What about Daylight Saving Time adjustments and leap seconds? Don't they bring duplicates of the same time or is there a way to account for that in the current system? --[[User:Muskar|Muskar]] ([[User talk:Muskar|talk]]) 10:06, 28 March 2014 (UTC)

:One hour is duplicated each year at the end of DST. Not much happens during that hour, because it's the middle of the night. A poorly written computer program that instructs the computer to set back the clock one hour whenever the clock reaches a specific time would get caught in a recursive loop (never advancing beyond that time). Properly, clocks are set back one hour when that time is first reached, but are allowed to advance after the duplicate hour concludes.

Leap second does not result in a duplicate. The additional second is allowed by increasing the number of seconds in a minute. Normally, the 60 seconds of 11:59 are numbered from 11:59:00 to 11:59:59, which is followed by 12:00:00. When there is a leap second, 11:59 has 61 seconds, numbered from 11:59:00 to 11:59:60 (61 total seconds) and then 11:59:60 is followed by 12:00:00.[[Special:Contributions/173.245.48.24|173.245.48.24]] 18:42, 29 March 2014 (UTC)

My first thought was that he makes fun of people that consider dates like the 12.12.12 as important. As any other date they occur only once and are thus not more special. [[Special:Contributions/108.162.254.66|108.162.254.66]] 04:37, 10 March 2014 (UTC)

:Good point, I have added something about that. [[Special:Contributions/108.162.246.117|108.162.246.117]] 04:49, 10 March 2014 (UTC)

Possibly related to the upcoming Pi Day. Also, next year's Pi Day will be 03-14-(20)15, which a few images going around on the Internet have made an annoyingly big deal about. [[Special:Contributions/108.162.237.64|108.162.237.64]] 06:24, 10 March 2014 (UTC)

So - Maybe I suck at searching (I do), but I can't find any information about us being limited to 4 digits in our calendar system...?[[Special:Contributions/173.245.53.107|173.245.53.107]] 08:38, 10 March 2014 (UTC)

:Most of the computer software that handles dates would have problems with more (or less) than four digits. Why bother with variable year length when you can just take the first four characters of "2014-03-10" and it works for the next 8 thousand years? [[Special:Contributions/103.22.200.103|103.22.200.103]] 09:42, 10 March 2014 (UTC)
:Also, most digital displays are limited to four digits for the year. [[Special:Contributions/103.22.200.103|103.22.200.103]] 09:43, 10 March 2014 (UTC)

::And I don't think we actually start address that sooner that in September 9999. It will be Y2K over again! .... not sure where will people of 9999 get {{w|Fortran}} and {{w|Cobol}} programmers, though. Maybe we should freeze some before we run out of them. :-) -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 10:20, 10 March 2014 (UTC)

:::Check [http://en.wikipedia.org/wiki/Unix_billennium#In_literature this] out.--[[User:Rael|Rael]] ([[User talk:Rael|talk]]) 21:38, 10 March 2014 (UTC)

:I'm with you. I suppose there may be places where leading zeros are used (somewhere in software where memory space has been set aside, I suppose) but I can't think of '''any''' common system where one has to use five digits when using a four digit number.
:When we get to December 31, 9999 (assuming he Gregorian calendar is still in use (BIG assumption)) the next day will simply be January 1, 10000 because, as you said, the Gregorian calendar isn't limited to four-digit years. And, as I say, anyone who think there is some problem with writing years as four digit numbers is simply demonstrating that they are not someone to take seriously. [[Special:Contributions/199.27.128.84|199.27.128.84]] 16:32, 10 March 2014 (UTC)

After visiting the website for the "Long Now Foundation", I find I'm left wondering - why, oh why, would they stop at using a five digit year? why not six? eight? ten? sixteen? thirty-two? [[User:Brettpeirce|Brettpeirce]] ([[User talk:Brettpeirce|talk]]) 12:06, 10 March 2014 (UTC)

I think the point in the comic title is that writing years always with 5 digits is as significant as the zero to the left it will take to do so for most of the next 8000 years. [[User:FlavianusEP|FlavianusEP]] ([[User talk:FlavianusEP|talk]]) 12:25, 10 March 2014 (UTC)

My first thought was that the comic was about date formats and yyyy-mm-dd being better than yy-mm-dd or dd.mm.yy. [[Special:Contributions/173.245.53.138|173.245.53.138]] 12:40, 10 March 2014 (UTC)

;Dynamic?

:It isn't, but I've made a dynamic one (based on UTC): https://voidptr.de/xkcd-1340 [[User:N.st|n.st]] ([[User talk:N.st|talk]]) 19:36, 12 March 2014 (UTC)

Wanna bet that this comic always shows the current date?--[[User:Henke37|Henke37]] ([[User talk:Henke37|talk]]) 10:23, 10 March 2014 (UTC)

:Haha, that's a great observation! I wish it were so, I'll check again tomorrow. If it's not, someone email Mr. Munroe to make it so, great idea. {{unsigned|Adityarajbhatt}}

:It's 00:07 (11th of March) right now in China where I am currently located and it still shows 10th of March...just for the record [[Special:Contributions/108.162.225.191|108.162.225.191]] 16:13, 10 March 2014 (UTC)

::It's March 15th now, and it still says the 10th. It's not dynamic. [[Special:Contributions/199.27.128.76|199.27.128.76]] 20:47, 15 March 2014 (UTC)
::It says 2014-10-01 for me. But I think it was at 11:53 (2014-09-30) when I checked it. And mine matches the atomic clock.
[[Special:Contributions/108.162.238.173|108.162.238.173]] 04:02, 1 October 2014 (UTC)

It's funny that Randall seems to have never heard of [http://tools.ietf.org/html/rfc2550 RFC 2550], which goes than the Long Now Foundation in expanding the representable date range. [[Special:Contributions/173.245.53.161|173.245.53.161]] 15:05, 10 March 2014 (UTC)

:Technically, there will be another 2014-03-10; on October 3rd. - [[Special:Contributions/108.162.219.65|108.162.219.65]] 16:01, 10 March 2014 (UTC)
::It would actually be 2014-10-03 "under our system" as stated in the comic. Technically. [[Special:Contributions/108.162.237.64|108.162.237.64]] 17:14, 10 March 2014 (UTC)
::It's like me saying that there will be another 2014-03-10 on March 14th. [[Special:Contributions/173.245.50.63|173.245.50.63]] 19:45, 10 March 2014 (UTC)

I wonder if this is also somehow related to the [http://en.wikipedia.org/wiki/Interesting_number_paradox Interesting number paradox]. [[Special:Contributions/199.27.128.29|199.27.128.29]] 18:48, 10 March 2014 (UTC)

The problem of the date rolling back is partially mitigated by storing the year as an integer instead of as characters, such as how certain Spreadsheet programs, such as OpenOffice Calc, stores years as a 16-bit signed integer. This doesn't solve the issue, only pushing it back to be the year 32768 problem. This is even less of an issue for 64 bit Unix time, which expire on 15:30:08 UTC on Sun, 4 December 292,277,026,596. It's also important to note that the dates, such as 99, or 00 should not be seen as digits, they should be seen as characters (unless, of course, they are BCD digits, which entirely defeats the purpose of shortening the date to 2 characters length). This might seem trivial, but I think it's an important difference.[[Special:Contributions/108.162.216.41|108.162.216.41]] 02:46, 11 March 2014 (UTC)
: 3rd of October won't happen for another seven months. {{unsigned ip|173.245.53.125}}
:: As a (culturally) dd/mm/[yy]yy person (and ignoring, for brevity, the different options for delimiter), I find yyyy-dd-mm as illogical as mm/dd/yyyy... Why should anybody switch 'precision direction', mid-way? Still, as someone who went through the Y2K process ''and'' worked with colleagues across the Atlantic, I tend to use dd/Mmm/yyyy habitually in "for humans" systems (giving the abbreviated month spelling to avoid all ambiguity, as well as full year-number), or my own "yyyymmdd[-hhmm[ss[.ddd...]]]" format in (informal and internal) programming situations, with comments attached to any conversion routines (inwards and outwards). ((And, yes, there ''are'' ISO/other standards, but I find converting from/to them and internally working with my own long-practiced format works best, for me. YMMV. But be aware of how'd you deal with (or ignore) Leap Seconds!)) [[Special:Contributions/141.101.98.47|141.101.98.47]] 14:58, 12 March 2014 (UTC)
::: I once toyed with the notation 0y20140310, with the "0y" prefix (a pun on C's "0x") distinguishing it from the eight-digit integer 20140310. I later decided that 0y20140310.175959 would be a good way to extend it to specify both date and time, and it still parses as a single C token if that property is useful. (And it sorts properly, of course.) [[Special:Contributions/199.27.128.68|199.27.128.68]] 04:15, 24 March 2014 (UTC)
I am surprised nobody has mentioned the fact that we know of no civilization of human beings that has reached 10,000 years with a continuous calendar.[[User:Seebert|Seebert]] ([[User talk:Seebert|talk]]) 14:15, 11 June 2014 (UTC)

290: Fucking Blue Shells

2014-06-18T17:55:55Z

108.162.238.173: /* Explanation */

{{comic
| number = 290
| date = July 16, 2007
| title = Fucking Blue Shells
| image = fucking_blue_shells.png
| titletext = You can evade blue shells in Double Dash, but it is deep magic.
}}

==Explanation==

Sometimes, something suddenly goes wrong and you can only shout obscenities at it. For instance, when the dog bites, when the bee stings, something unexpected happens, or a program crashes (e.g. a {{w|Segmentation fault|segfault}}) the victim often reacts by swearing.

For [[Randall]], however, profanities are caused mostly by blue shells in the video game {{w|Mario Kart}}. The blue shells, when fired, target the player currently in first place and stop them cold. In a close game, a player can go from first to an unrecoverable last in one hit.

The title text refers to the "{{w|Mario_Kart:_Double_Dash!!|Double Dash}}" edition of Mario Kart. This includes a technique to avoid being hit by a blue shell, but it requires skillful timing to accomplish. The term "deep magic" is a reference to {{w|The Chronicles of Narnia}}, in which Aslan explains away a seeming miracle as such.

==Transcript==
:My Profanity Usage By Cause:
:[Pie chart is shown.]
:[Injury is about 5% of pie chart.]
:[Irony is about 5% of pie chart.]
:[Misc is about 5% of pie chart.]
:[Segfaults is about 10% of pie chart.]
:[Mario Kart is about 75% of pie chart.]

{{comic discussion}}
[[Category:Charts]]
[[Category:Comics with color]]
[[Category:Video games]]
[[Category:Mario Kart]]