Wikipedia talk:WikiProject Mathematics/Archive/2017/Apr

Digits of pi
Various redirects related to pi to various lengths have been nominated at Redirects for discussion/Log/2017 April 1 and [[Wikipedia:Redirects for discussion/Log/2017 April 1. As part of the latter discussion I have suggested creating a reference page, probably on Wikibooks, of Pi to various number of digits. Your comments in both discussions, both generally and related to the specific suggestion, are more than welcome. Thryduulf (talk) 11:46, 3 April 2017 (UTC)

Add Markov number page to the Mathematics project?
The talk page for Markov number attaches it to the Russia project, but I can't help feeling that the page is more relevant to non-Russian mathematicians than to Russian non-mathematicians! I admit a personal interest in getting the page more attention: the desire to get a a second opinion on my "disputed" annotation in the "Other Properties" section, now several months old. Chris Thompson (talk) 15:36, 4 April 2017 (UTC)
 * I added a math project banner. Historically, we haven't done that for all of our articles, though, because they're in list of mathematics articles, so the banner is only needed if someone wants to add an actual rating of the article. —David Eppstein (talk) 15:48, 4 April 2017 (UTC)

Relevant ANI thread
There is currently a thread at Administrators' noticeboard/Incidents which could benefit from some motivated volunteers from this WikiProject with a keen understanding of WP:BLP. Timothy Joseph Wood 15:23, 2 April 2017 (UTC)
 * Now at AfD; see Articles for deletion/Teo Mora. —David Eppstein (talk) 15:54, 4 April 2017 (UTC)

Fields need your help!
We used to have a collaboration of the month or something like that a while ago. I invite all of you to work on the article about fields. It is a top-level article, should be accessible to a broad audience. Please join in making this article a showpiece of what Wikipedia can do! Jakob.scholbach (talk) 16:43, 5 April 2017 (UTC)

Non-example versus counterexample
According to D.Lazard, "non-example" is an absurdity, as meaning "not an example", see his edit summary here. Well, but then a lot of articles should be changed accordingly, see here. Boris Tsirelson (talk) 11:23, 8 April 2017 (UTC)


 * I have replied at Talk:Continuous function, and would encourage others to do the same.  Sławomir Biały  (talk) 13:15, 8 April 2017 (UTC)

Over?-enthusiastic newish user
Newish user has been editing a number of mathematics articles with information related to games; the ones I noticed are List of NP-complete problems, decidability, Mathematics of Sudoku, combinatorial explosion, perfect information, game complexity, brute-force search, and determinacy. Some of their edits are clearly fine, but I've seen questions raised separately by and  about others and wanted to draw a bit more attention. My interactions suggest that the user is good-natured but doesn't really understand the important of sourcing, and probably doesn't have a good grasp of the mathematical issues raised by some of their edits. --JBL (talk) 13:31, 10 April 2017 (UTC)
 * Just let me know if you see any material I added that is not properly referenced. I'll be happy to go back and help amend or improve such statements. Also, please be advised that in some cases my edits were to address exactly the issue that you have raised. In more than one instance I have added or  tags related to statements added by other users. These were removed without resolution at any Talk page. An example is here: User_talk:David_Eppstein.—LithiumFlash (talk) 14:01, 10 April 2017 (UTC)

Envelope model
Hi, I would really appreciate some independent expert eyes to take a look at Articles_for_deletion/Envelope_model. I simply have no idea if this is a genuinely important topic in stats or not. Your contributions are greatly appreciated! Best, Nicnote  •  ask me a question  •  contributions  22:44, 14 April 2017 (UTC)
 * Ping -, would you mind pinging anyone else who may be interested? Thanks! Nicnote  •  ask me a question  •  contributions  22:48, 14 April 2017 (UTC)
 * Not really my specialty but I'll try to look into it this week. --JBL (talk) 00:53, 17 April 2017 (UTC)
 * and (I nearly forgot a fellow countryman...)  Nicnote  •  ask me a question  •  contributions  23:06, 14 April 2017 (UTC)

'jackson' ?
Nine years ago, this image was uploaded with the claim that it illustrates 'Jackson's Theorem' on representing higher dimensions. I've found no evidence of such a theorem existing, but this isn't my field and I may not be able to think of the right search terms. So (leaving aside its low quality), is this a legitimate image? DS (talk) 00:28, 17 April 2017 (UTC)
 * It appears to be part of some nine-year-old chatbot spam (see User:Superchild123 and note that that user's only contributions were the creation of that user page and some older now-deleted images). I think the image and the user page are both safe to remove. —David Eppstein (talk) 00:38, 17 April 2017 (UTC)
 * Doesn't look serious to me. --JBL (talk) 00:53, 17 April 2017 (UTC)
 * To be 100% fair, the Superchild thing was an issue of reusing image names: deleted contribs show that the account uploaded some guy in a labcoat as "jackson.jpg" in March '08, and the crumpled-up paper was uploaded in May '08. But since you confirm that it's garbage, I'll file a deletion notice on Commons. DS (talk) 04:55, 17 April 2017 (UTC)

GF(2)
Please see Talk:GF(2) (since I don't think that talk page is watched by many).--Jasper Deng (talk) 04:55, 17 April 2017 (UTC)

Propagation of errors resulting from algebraic manipulations
, currently a redirect to Propagation of uncertainty, has been nominated for deletion. The discussion at Redirects for discussion/Log/2017 April 16 needs input from those with knowledge of the subject. Thryduulf (talk) 13:37, 17 April 2017 (UTC)

RfC on the WP:ANDOR guideline
Hi, all. Opinions are needed on the following: Wikipedia talk:Manual of Style. A WP:Permalink for it is here. Flyer22 Reborn (talk) 22:48, 17 April 2017 (UTC)

Moving onto the next topic: Is there anyway that this is right?
I would move on to the next next topic. "onto" is a perfectly respectable word and "on to" is a perfectly respectable phrase and they mean two different things. I would not move "onto" the next topic. Likewise "anyway" and "any way". So how about this edit? One could maintain that "plug in" is a phrasal verb used here. Michael Hardy (talk) 03:31, 17 April 2017 (UTC)


 * Isn't this convincing enough? Boris Tsirelson (talk) 04:49, 17 April 2017 (UTC)


 * It's quite a hubris to plug my opinion on this topic into your attention, but having plugged in that I consider replacing the phrasal verb "to plug in" by the more elaborate "to apply a substitution homomorphism" as a dramatic exaggeration, it's conceiveable that imho any editing along these lines is somewhat excessive nitpicking on both sides. On a more personal side, I faintly prefer the use of non-phrasal verbs, if possible. :) Purgy (talk) 06:24, 17 April 2017 (UTC)
 * Are you missing the point as completely as possible or did I miss something. I did not object to the phrase "plug in". Michael Hardy (talk) 20:17, 17 April 2017 (UTC)


 * Yes, I obviously missed both of your intentional abuses in the title, and, perhaps wrongly, assumed you taking sides strictly against the cited edit. I apologize for any discontent I might have caused with my remarks.
 * Even in the light of the link given by Tsirel, to me there are both variants obviously feasible, (therefore) a discussion about this is nitpicking in my valuation, and I agree to Sławomir Biały, enjoying the XKCD-link.
 * Of course, I may be wrong, but in any case I never intended to be offensive or to hurt someones feelings. Purgy (talk) 06:40, 18 April 2017 (UTC)
 * Addendum: To avoid further nitpicking I wont take part in the RfC below, even when strongly disliking and/or. Purgy (talk) 06:46, 18 April 2017 (UTC)


 * All I have to say is --JBL (talk) 11:48, 17 April 2017 (UTC)

Can we just abolish the phrase "plug in" from all mathematical discourse and be done with the matter? Sławomir Biały (talk) 12:31, 17 April 2017 (UTC)

An extra set of eyes on Quartic Function please?
I've run through the Ferrari method with two depressed quartics (https://en.wikipedia.org/wiki/Quartic_function#Ferrari.27s_solution) one worked fine (x^4-5x²+10x-6), but one gave all roots times -1 (x^4+5/8x²-5/8x-51/256). I used a spreadsheet, so they are both using the same equations. I followed the derivation to produce the equation, and it seems valid. Can someone else please look at it to see if there is a problem? I've started a discussion on the article talk page. Is there a point where sometimes the negative square root must be used, while other times it's the positive square root?Beakerboy (talk) 17:26, 18 April 2017 (UTC)

Is "multiplicative inverse" the primary meaning of "reciprocal"?
There's a discussion on whether reciprocal, now a disambiguation page, should instead redirect to multiplicative inverse (with the disambiguation page moved elsewhere). Please participate at Talk:Reciprocal. —David Eppstein (talk) 23:14, 18 April 2017 (UTC)

Parallel projection
User:SharkD removed a new version of the article parallel projection, which I recently wrote. I would appreciate a third opinion on the talk page of the article. Thank You !--Ag2gaeh (talk) 15:11, 20 April 2017 (UTC)

Poincaré plot
The article Poincaré plot looks short to me. Can someone take a look at it? Thank you. RJFJR (talk) 16:20, 29 April 2017 (UTC)