explain xkcd - User contributions [en]

Talk:2595: Advanced Techniques

2022-03-20T18:32:12Z

172.70.246.55:

The title text refers to [[wikipedia:Noether's theorem|Noether's theorem]]. [[User:Trimeta|Trimeta]] ([[User talk:Trimeta|talk]]) 04:24, 19 March 2022 (UTC)

This is my first explanation [[User:GcGYSF(asterisk)P(vertical line)e|GcGYSF(asterisk)P(vertical line)e]] ([[User talk:GcGYSF(asterisk)P(vertical line)e|talk]]) 05:41, 19 March 2022 (UTC)

This sounds a lot like Laplace or Fourier transforms, converting a function into a different where it is easier to manipulate then reversing the transformation. [[Special:Contributions/108.162.245.173|108.162.245.173]] 06:28, 19 March 2022 (UTC)
:When I was learning to use fourier transforms in EE, they were very straightforwardly (and accurately) described as "transferring the function to the Spectral Domain". [[Special:Contributions/172.70.110.241|172.70.110.241]] 22:45, 19 March 2022 (UTC)

I'm not sure that it's proper to refer to someone as a "giant" while explaining a comic that references mythological creatures. Unless it was literal of course, but as far as I'm aware giants never existed. [[Special:Contributions/162.158.111.12|162.158.111.12]] 11:28, 19 March 2022 (UTC)
:I think she may actually have been a wizard-giant.[[User:Iggynelix|Iggynelix]] ([[User talk:Iggynelix|talk]]) 13:41, 19 March 2022 (UTC)

Not my area, but I am passingly familiar with the [[:wikipedia:Gauss–Kuzmin–Wirsing_operator|Gauss–Kuzmin–Wirsing Operator]], [[wikipedia:Dragon curve|Dragon Curves]], and [[wikipedia:Hilbert spaces|Hilbert ''Spaces'']] (guessing that the "arrow" refers to scalar vector?). Some type of iterative/recursive conversion that yields to analysis of the period? Probably not pertinent to the joke which is more about the fanciful names attached to mathematical concepts, constructs, and processes [[Special:Contributions/108.162.245.173|108.162.245.173]] 11:53, 19 March 2022 (UTC)

I find it inteteresting that despite now being the day after release (or well into the next day, my time, which is usually sufficient — and I'm not in a DST zone yet) the site explanation hasn't explained (or thought it has explained) every single element of the in-comic 'explanation' — even if not established the (probably) nonsensical whole. As an example, I don't yet see the obvious {{w|Dragon_curve|dragon}} element that is both alluded to ''and'' seemingly illustrated upon the board-notes. Leaving this here to help near-future editors who might have time to bullet-point/tabulate/sub-heading these things and just need that extra bit of info. [[Special:Contributions/162.158.159.125|162.158.159.125]] 15:01, 19 March 2022 (UTC)

There is the misquote of Arthur Clarke "All sufficiently advanced [strike]technologies[/strike] mathematical techniques are indistinguishable from magic." [[User:Arachrah|Arachrah]] ([[User talk:Arachrah|talk]])
:Fix it!
:[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 23:28, 19 March 2022 (UTC)

The explanation should decide whether the teacher is Miss Lenhart, or Blondie. I think it's Miss Lenhart. [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 17:02, 19 March 2022 (UTC)

That dragon looks suspiciously like Trogdor...[[Special:Contributions/162.158.146.73|162.158.146.73]]
:It just looks like a normal wyvern to me, though the perspective doesn't give us much detail to help tell those two cases apart. I think if it ''were'' Trogdor though, fewer liberties would have been taken with the shape of the dragon's body. (To be confident we would have to figure out the original problem and use Gauss' operator ourselves to get a more detailed look, which seems difficult.) [[Special:Contributions/141.101.104.11|141.101.104.11]] 16:25, 20 March 2022 (UTC)

"Critical Role: Call of the Netherdeep" released this week, for D&D 5e.
[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 23:28, 19 March 2022 (UTC)

Come to think of it, we do use fantasy-sounding expressions in math: e.g. titanic prime, imaginary part, infinite field, ideals, friendly numbers, brute force attack. I'm pretty sure there are many more fun examples.

PS: "Sexy primes" and "latus rectum" are real technical terms.
[[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 04:16, 20 March 2022 (UTC)

PPS: Its weird how this fantastic math have failed to solve the 3n+1 problem. Because I do believe I have solved it within this week. [[Special:Contributions/172.70.246.55|172.70.246.55]] 18:31, 20 March 2022 (UTC)

Talk:2595: Advanced Techniques

2022-03-20T18:31:36Z

172.70.246.55:

The title text refers to [[wikipedia:Noether's theorem|Noether's theorem]]. [[User:Trimeta|Trimeta]] ([[User talk:Trimeta|talk]]) 04:24, 19 March 2022 (UTC)

This is my first explanation [[User:GcGYSF(asterisk)P(vertical line)e|GcGYSF(asterisk)P(vertical line)e]] ([[User talk:GcGYSF(asterisk)P(vertical line)e|talk]]) 05:41, 19 March 2022 (UTC)

This sounds a lot like Laplace or Fourier transforms, converting a function into a different where it is easier to manipulate then reversing the transformation. [[Special:Contributions/108.162.245.173|108.162.245.173]] 06:28, 19 March 2022 (UTC)
:When I was learning to use fourier transforms in EE, they were very straightforwardly (and accurately) described as "transferring the function to the Spectral Domain". [[Special:Contributions/172.70.110.241|172.70.110.241]] 22:45, 19 March 2022 (UTC)

I'm not sure that it's proper to refer to someone as a "giant" while explaining a comic that references mythological creatures. Unless it was literal of course, but as far as I'm aware giants never existed. [[Special:Contributions/162.158.111.12|162.158.111.12]] 11:28, 19 March 2022 (UTC)
:I think she may actually have been a wizard-giant.[[User:Iggynelix|Iggynelix]] ([[User talk:Iggynelix|talk]]) 13:41, 19 March 2022 (UTC)

Not my area, but I am passingly familiar with the [[:wikipedia:Gauss–Kuzmin–Wirsing_operator|Gauss–Kuzmin–Wirsing Operator]], [[wikipedia:Dragon curve|Dragon Curves]], and [[wikipedia:Hilbert spaces|Hilbert ''Spaces'']] (guessing that the "arrow" refers to scalar vector?). Some type of iterative/recursive conversion that yields to analysis of the period? Probably not pertinent to the joke which is more about the fanciful names attached to mathematical concepts, constructs, and processes [[Special:Contributions/108.162.245.173|108.162.245.173]] 11:53, 19 March 2022 (UTC)

I find it inteteresting that despite now being the day after release (or well into the next day, my time, which is usually sufficient — and I'm not in a DST zone yet) the site explanation hasn't explained (or thought it has explained) every single element of the in-comic 'explanation' — even if not established the (probably) nonsensical whole. As an example, I don't yet see the obvious {{w|Dragon_curve|dragon}} element that is both alluded to ''and'' seemingly illustrated upon the board-notes. Leaving this here to help near-future editors who might have time to bullet-point/tabulate/sub-heading these things and just need that extra bit of info. [[Special:Contributions/162.158.159.125|162.158.159.125]] 15:01, 19 March 2022 (UTC)

There is the misquote of Arthur Clarke "All sufficiently advanced [strike]technologies[/strike] mathematical techniques are indistinguishable from magic." [[User:Arachrah|Arachrah]] ([[User talk:Arachrah|talk]])
:Fix it!
:[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 23:28, 19 March 2022 (UTC)

The explanation should decide whether the teacher is Miss Lenhart, or Blondie. I think it's Miss Lenhart. [[User:Nitpicking|Nitpicking]] ([[User talk:Nitpicking|talk]]) 17:02, 19 March 2022 (UTC)

That dragon looks suspiciously like Trogdor...[[Special:Contributions/162.158.146.73|162.158.146.73]]
:It just looks like a normal wyvern to me, though the perspective doesn't give us much detail to help tell those two cases apart. I think if it ''were'' Trogdor though, fewer liberties would have been taken with the shape of the dragon's body. (To be confident we would have to figure out the original problem and use Gauss' operator ourselves to get a more detailed look, which seems difficult.) [[Special:Contributions/141.101.104.11|141.101.104.11]] 16:25, 20 March 2022 (UTC)

"Critical Role: Call of the Netherdeep" released this week, for D&D 5e.
[[User:ProphetZarquon|ProphetZarquon]] ([[User talk:ProphetZarquon|talk]]) 23:28, 19 March 2022 (UTC)

Come to think of it, we do use fantasy-sounding expressions in math: e.g. titanic prime, imaginary part, infinite field, ideals, friendly numbers, brute force attack. I'm pretty sure there are many more fun examples.

PS: "Sexy primes" and "latus rectum" are real technical terms.
[[User:Yosei|Yosei]] ([[User talk:Yosei|talk]]) 04:16, 20 March 2022 (UTC)

PPS: Its weird how this fantastic math have failed to solve the 3n+1 problem. Because I believe I have solved it within this week. [[Special:Contributions/172.70.246.55|172.70.246.55]] 18:31, 20 March 2022 (UTC)

Talk:2586: Greek Letters

2022-03-08T11:08:00Z

172.70.246.55:

Pi also shows up in lots of extremely advanced equations as pi, not as something else, adding edit. 123.456.7890

zeta_0 is also used for the first transfinite ordinal that is unreachable through ''((edit: by some random IP: "...finite application of..."))'' addition, multiplication, exponentiation, and epsilons subscripting. EDIT: phi is used for the Veblen hierachy. [[User:GcGYSF(asterisk)P(vertical line)e|GcGYSF(asterisk)P(vertical line)e]] ([[User talk:GcGYSF(asterisk)P(vertical line)e|talk]]) 05:11, 26 February 2022 (UTC)
:I wouldn't normally internally spellcheck/factcheck someone's signed Talk comment, as I think it's rude to do so (especially 'invisibly'), but an IP added some words to yours (without clear indication) probably with good reason but also with slightly bad typing. So I've highlighted their (corrected) addition, which at first sight seems a valid clarification but I haven't double-checked. And now this is me taking fully (IP-)signed ownership of what I changed. Would have been simpler for the prior editor just to have made a signed-reply, like this but far shorter, but they didn't! Ah well... [[Special:Contributions/172.70.90.121|172.70.90.121]] 14:03, 1 March 2022 (UTC)

Don't you have an English saying: '''simple/easy as π'''? [[User:Nukio|Nukio]] ([[User talk:Nukio|talk]]) 05:51, 26 February 2022 (UTC)
:the saying is '''easy as pie''' as in the dessert. sometimes we write it '''easy as π''' as a nerdy joke. [[Special:Contributions/162.158.107.230|162.158.107.230]] 08:08, 26 February 2022 (UTC)
:: sqrt(-1) 2³ Σ π and it was delicious [[User:Elektrizikekswerk|Elektrizikekswerk]] ([[User talk:Elektrizikekswerk|talk]]) 08:30, 28 February 2022 (UTC)

Related: https://xkcd.com/2520/ [[Special:Contributions/162.158.103.224|162.158.103.224]] 08:59, 26 February 2022 (UTC)

I've found a use for capital Xi: https://en.wikipedia.org/wiki/Harish-Chandra%27s_%CE%9E_function that seems to be from the field of Harmonic Analysis. [[User:Douira|Douira]] ([[User talk:Douira|talk]]) 14:50, 26 February 2022 (UTC)

The part that says the farad is "unusually large" is incredibly biased IMO. On the scale of planets its "unusually small", In fact, on the scale of EV's its even pretty normal. The writer is only considering small electronic circuits. Also the Henry is very well scaled to the Farad so how "unusual" is it really? [[Special:Contributions/108.162.241.33|108.162.241.33]] 17:13, 26 February 2022 (UTC)

:Apologies for the incredible bias. You're right in saying that I'm only considering small electronic circuits; I haven't worked on power distribution systems or applications with large capacitor banks, so my only hands-on experience of components measured in whole farads would be supercapacitors. In consumer electronics, where capacitors are typically labelled in pico, nano or microfarads, the whole farad is rarely encountered. I do still think that capacitors are a good counter-example of items using Mu that you can see and touch, in so many modern electronic devices. But as my previous use of language was so divisive, I'll let someone else attempt to reintegrate the point, if they feel it's useful. [[User:Kazzie|Kazzie]] ([[User talk:Kazzie|talk]]) 16:11, 27 February 2022 (UTC)

Isn't the ''capital'' psi used for the wavefunction? [[User:GcGYSF(asterisk)P(vertical line)e|GcGYSF(asterisk)P(vertical line)e]] ([[User talk:GcGYSF(asterisk)P(vertical line)e|talk]]) 19:35, 26 February 2022 (UTC)
:Yes, but rarely. The lowercase ψ is much more common (AFAIK it dates back to [https://commons.wikimedia.org/wiki/File:Grave_Schroedinger_(detail).png Schrödinger himself].

How sad that there is no '''η'''! Missed chance to blame steam machine engineers for not trying harder to invent the perpetuum mobile. --[[Special:Contributions/172.70.242.177|172.70.242.177]] 20:01, 26 February 2022 (UTC)

The lowercase epsilon is used much more often for something else - usually to denote that the "variable" on the lefthanded side is a member of the "set" of the righthanded side of the lowercase epsilon. Of course, this is totally unimportant ;-).
:You are referring to the "element of" sign, which is distinct from lowercase epsilon (although based on it).
:: Yes it is distinct, but then the used typeface in the comic looks more like the epsilon for "element of" then for the usual epsilon in analysis (ie. for definitions of continues functions).

I highly doubt that the use of Ξ has anything to do with it "looking like a UFO." Rather, I'd suggest it's because it's essentially never used, at least among the English speaking mathematicians in the US, and probably Europe. [[User:Douira|Douira]] went out of their way to find an example, and found something increadibly obscure, which supports the point. ''Why'' Ξ is rarely used is another question. Maybe because it could easily be confused for an E or Sigma, with lazy handwritting? Maybe because it's a Greek letter without a direct Latin counterpart, so doesn't correspond with the first letter of any common words? [[Special:Contributions/162.158.63.49|162.158.63.49]] 22:50, 26 February 2022 (UTC)som

In my experience lower case eta, zeta, (and xi) most commonly show up as dummy variable in an integral. Any two may be used for a double integral and all three for a triple. Double and triple integrals are often quite terrifying, particularly when somebody cannot write all three symbols consistently and distinctly, so many integrals become "integral squiggle squiggle dee squiggle dee squiggle".[[Special:Contributions/172.70.174.219|172.70.174.219]] 10:10, 27 February 2022 (UTC)

π is also commonly used as the [https://en.wikipedia.org/wiki/Prime-counting_function prime-counting] function in number theory. Most problems regarding primes are usually considered hard, like the twin prime conjecture.

Lower-case sigma is also used in sigma-algebras, which is part of the theoretical background underlying statistics, among other things. I second that the lower-case epsilon drawn by Randall is the lunate variant that looks indistinguishable from the "is an element of" symbol and should probably get mentioned. On an unrelated note, there's a story of someone using capital xi at a math conference specifically to annoy some other mathematician who *really* didn't like them. [[Special:Contributions/172.70.211.26|172.70.211.26]] 20:30, 27 February 2022 (UTC)

:Yeah I came to comment this, lower-case sigmas come up in sigma-algebras and are absolutely terrifying (bias) in that context. The joke about ‘someone trying very hard to apply this’ works with sigma-algebras in the context of measure theory -- someone trying to actually apply measure theory to a real problem. [[Special:Contributions/162.158.129.117|162.158.129.117]] 10:48, 28 February 2022 (UTC)

Alpha is also used in aeronautics for the angle of attack of the airflow over a wing. Exceeding a critical angle of attack leads to an aerodynamic stall, which has been cause of many fatal accidents.

Uppercase phi looks like an obvious reference to [https://twitter.com/nathanwpyle/status/1178152201392447488| this comic and author], as he normally uses the term orb to refer to spheres and balls (as part of the intrincate language of the characters), besides he normally uses that typographic resource of writing a word with its letters separated by spaces, i.e.: e x p e r i e n c e, in the example link. I'm missing the math context on why refering to orbs for uppercase phy, but it could be just because due to the form of the character. [[Special:Contributions/172.70.86.54|172.70.86.54]] 10:28, 28 February 2022 (UTC)

The lowercase gamma symbol and description may also be a reference to the downward-looping flight path of enemy ships in the video-game Galaga, which zoom down the screen at the player's starfighter while shooting at them, then retreat and zoom back up. [[Special:Contributions/172.70.131.122|172.70.131.122]]

Why was my remark on the impossibility of {{w|squaring the circle}} removed? (https://www.explainxkcd.com/wiki/index.php?title=2586:_Greek_Letters&diff=227689&oldid=227680) [[User:ThomasGauss|ThomasGauss]] ([[User talk:ThomasGauss|talk]]) 20:06, 28 February 2022 (UTC)

My sibling's in an advanced calculus course, when she saw the joke about lowercase omega she laughed for a different reason, remarking how accurate it was and how impossible it is to use in her class? (I can't remember exactly.) I don't understand what she meant, I'm in a lower class. Could somebody add an alternate explanation possibly? 123.456.7890

:Differential forms? [[Special:Contributions/172.70.230.111|172.70.230.111]] 03:24, 2 March 2022 (UTC)

::Yes, that's it. I still have no idea how they work, though. 123.456.7890

O R B S are chanted with such gravitas in the Games Done Quick speedrunning fundraiser events. I would say this is a niche pull, but it seems up Randall's alley.

Why is Randall so good at making me crack up? Am I really that much of a nerd? (Okay granted I needed an explanation for some of this, hence my presence here, but still, Addition® and Multiplication® Pro® got me so...)--[[User:Twisted Code|Twisted Code]] ([[User talk:Twisted Code|talk]]) 17:10, 4 March 2022 (UTC)

It just occurred to me Poseidon could be written as Poψdon. Then his trident is in his name. [[User:Bwisey|Bwisey]] ([[User talk:Bwisey|talk]]) 13:11, 5 March 2022 (UTC)

One thing missed so far, the lowercase epsilon is also used in automata theory. There usually words (strings of symbols from an alphabet), which do contain lowercase epsilons, are equivalent to the same word, after removing any occurence of lowercase epsilon from the string. Ie. the lowercase epsilon there denotes the "empty symbol" (or "empty letter"). For further reading ie. look up non determitistic finite automata with (and without) epsilon transitions. Also in other branches of theoretical computer science the lowercase epsilon is usually used as "empty symbol" or "empty letter".