Talk:Polar coordinate system

message: This article has been edited by a user who is known to have misused sources to unduly promote certain views (see WP:Jagged 85 cleanup). Examination of the sources used by this editor often reveals that the sources have been selectively interpreted or blatantly misrepresented, going beyond any reasonable interpretation of the authors' intent.
Please help by viewing the entry for this article shown at the page, and check the edits to ensure that any claims are valid, and that any references do in fact verify what is claimed. 
I searched the page history, and found 3 edits by Jagged 85 (for example, see this edits).  Tobby72 (talk) 21:00, 16 January 2012 (UTC)
replies: text: I went ahead and removed the paragraph on Biruni which is the material in question. The first statement, citing MacTutor, uses a WP:WEASEL phrase ("are seen as"), and MacTutor doesn't give any additional information on this. I didn't verify the second statement on azimuthal equidistant projection since the source isn't freely available online, but it seems off-topic for this article anyway so the issue is moot. Perhaps someone with a Questia.com account can research this further but I think the statement, if verifiable, would belong the article on the projection rather than here.--RDBury (talk) 16:10, 17 January 2012 (UTC)
thread_title: Misuse of sources

message: An interesting technicality is whether there is a "standard" polar coordinate system and, if so, does it specify that the radius r must be non-negative?  Clearly one can make sense of an expression like r cos(theta) if r is negative and convert such an (r,theta) to a cartesian coordinate (x,y).  However, converting the point (x,y) back to a polar coordinate by the usual method would produce a point where r was positive. 
I see nothing that prevents a "polar equation" from having a negative r value.  So I wonder if polar equations are required to produce "standard" polar coordinates or whether they merely produce numbers than can be converted to standard polar coordinates.
Perhaps the people that know about the "chart and atlas" treatment of coordinate systems for manifolds can comment on whether there is a standard polar coordinate system.
Tashiro (talk) 19:38, 2 April 2012 (UTC)
replies: text: It is standard to have r non-negative and θ in the range (−π, π]. You can of course have angles or radius outside of those ranges but that would be a non-standard representation. To produce an atlas the easiest thing is to use a different range of angles, however you have problems with that though for defining a manifold as the origin can have any angle, you' need to do that with some other coordinate system entirely and just leave that out otherwise. Dmcq (talk) 22:55, 2 April 2012 (UTC)

text: I think I mustn't be understanding what you mean by standard. It is not something that is dictated by some higher mathematical rule, it is simply what people do. What is in the article is as standard as one gets without getting an agreed ISO standard and that isn't done in maths. Some people have used an angle from 0 to 2π instead but that's a distinct minority and what's here is what you'll practically always get. Dmcq (talk) 07:40, 3 April 2012 (UTC)

text: The article gives the normal standard polar coordinates as r non-negative and θ in the range (−π, π]. What more do you need than that? That is as standard as one gets. The only other range that is sometimes used but is nowhere near so common is θ in the range [0,2π). There is no more to it. I really don't see what problem you see with that. It is possible to have an equation like r=θ which defines a spiral where θ goes out of that range but there's no difference between that and saying that the square root of 4 is 2 but that −2 is a square root of 4. That's referred to as the principal square root and the value in (−π, π] is the principal value here. Dmcq (talk) 22:59, 3 April 2012 (UTC)

text: I think what you are saying is you'd like the text to say the conversion is to the standard range as specified in the section about a unique conversion. I'll try rephrasing it and see how that goes. Dmcq (talk) 16:39, 8 April 2012 (UTC)
thread_title: Polar equations vs polar coordinates

message: I could write something about this topic if someone thinks it could be useful / is not covered anywhere. Note that when i was studying this sort I thing i was unable to find any reference online (except for some research articles). --Agi 90 (talk) 11:48, 1 June 2012 (UTC)
replies: text: Yes please, the anti-de Sitter space currently contains a red-link hyperpolar coordinates, as do some of the articles on geodesics. This is a standard topic for Riemannian geometry, it should have an article.  Probably does, just under some name I can't think of ... Hmm. It would be great if you could make it clear that its for symmetric spaces with O(n) orthogonal group symmetry, and then explore the general case. Hmm. User:Linas (talk) 02:29, 3 November 2013 (UTC)
thread_title:  Polar coordinates in <math>n</math> dimensions 

message: I am not sure if it is a space or a variation on the polar coordinates. For instance, using the notation (r, theta) for a point, the point (r0, theta) != (ro, theta+2*pi). Hence the plane/space/coordinate system is sort of a spiral. What is this called?  — Preceding unsigned comment added by 68.228.41.185 (talk) 08:25, 1 November 2012 (UTC)
replies: text: Perhaps you are thinking of a covering space or a universal cover ? User:Linas (talk) 02:31, 3 November 2013 (UTC)
thread_title:  What is the extension / generalization to a spiral plane? 

message: This article is full of short paragraphs and sections and is, for the most part, devoid of inline citations. In addition, the intro is very short and the prose contains some awkwardly constructed sentences. Though I won't nominate it for an FAR right now, I don't believe it meets the 2014-era FA criteria. Tezero (talk) 02:47, 27 July 2014 (UTC)
thread_title:  FA? 

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thread_title:  External links modified 

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thread_title:  External links modified 

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thread_title:  External links modified 

message: Regardless to whom WP:BRD applies, I enjoy repeating the facts, given already in my edit summary.
# "arctan" is a multivalued map —\arctan:\;\mathbb R \to \mathbb R— and is NOT a function.
# The usual selection of a principal branch restricts the codomain to principal values from the interval (-\pi/2, \pi/2). Except for the value \pi/2 this exhausts the full domain (-\pi/2, \pi/2], admissible for the polar angle in this concept, suggesting the mentioned association.
#This restriction generates a function, that maps \mathbb R \to (-\pi/2, \pi/2). This function has the generally agreed upon denotation of "\operatorname{Arctan}", which justifies the use of this name at the place under discussion.
No rational reasoning for using "\arctan" instead was given yet. Purgy (talk) 07:41, 17 September 2018 (UTC)
replies: text:  Assertion does not a fact make. The distinction you are making isn't apparent in the article, of itself, nor in the arctan article. Nor do I see a more general convention of differentiating maps and functions in mathematics by the first letter of their name. If you want to have this convention on Wikipedia, you're going to have to go ahead and put the work in so that everyone knows what it means. 178.16.3.163 (talk) 18:29, 17 September 2018 (UTC)
replies: text:  I would suggest that the arctan article would be the only place to start. 178.16.3.163 (talk) 18:33, 17 September 2018 (UTC)

text:  None has to be given. It is entirely up to you to justify your change on the talk page. That's how BRD works. 178.16.3.163 (talk) 18:24, 17 September 2018 (UTC)
replies: text: Well this is a little confusing. As I read the history page the original change from "Arctan" to "arctan" was made by you and not Purgy, putting the onus of justification upon you. Be that as it may, I am familiar with the convention of capitalizing the first letter of these inverse trig multivalued expressions to indicate that a function is meant, but unfortunately I am on vacation at the moment and am unable to document that fact. --Bill Cherowitzo  (talk) 18:54, 17 September 2018 (UTC)
replies: text:  I am happy to revert his entire change directly, if that makes it easier for the usual narrow application of WP:BRD to take place. 178.16.3.163 (talk) 18:59, 17 September 2018 (UTC)
thread_title:  "arctan" ''vs.'' "Arctan" 

message: It is conventional within mathematics to denominate the angle in radians, and to diagram polar coordinates by placing the zero angle along the positive abscissa, with increasing angles progressing counterclockwise.
Half a math degree thirty years ago, and this is now the best I can do. :-( But at least I know what needs to be said, if not necessarily how to best say it. 
Likely this would benefit from some fine tuning. (Note also, I wasn't able to lift optimal text from the radians article on scant inspection, so there's a potential edit there, too.) — MaxEnt 22:31, 13 February 2019 (UTC)
replies: text: I reverted your addition because there is a full section dealing with the various conventions, and because the "pos. abscissa" comes into existence only when referencing Cartesian coordinate systems, and this conversion is also covered in the article. I think one could discuss if the lead should contain hints to (1)different conventions re radians or degrees, or other units, (2)different orientational conventions, and (3)connections to various other coordinate systems, e.g. also the higher dimensional extensions. All these topics are addressed in the article. Purgy (talk) 08:06, 14 February 2019 (UTC)
thread_title:  Positive abscissa, progressing counterclockwise 

message: Hi editors, as part of WP:URFA/2020 I reviewed this article and I do not believe it meets the featured article criteria anymore. I am concerned that there are multiple uncited sentences and paragraphs throughout the article, and the "General references" section should be used as footnotes throughout the article. Is anyone interested in bringing this back to FA quality? Z1720 (talk) 22:47, 10 April 2021 (UTC)
replies: text: I would love to help, though I am quite certain my skills are lacking. Having seen the "review" of this article, I foresee a tough climb ahead. Please do call on me if necessary or appropriate. Horsesizedduck (talk) 23:54, 29 June 2021 (UTC)
replies: text:  If you are interested in working on the article, please comment on the article's FAR. I am not knowledgeable enough to edit this, but there are other editors with expertise who would be willing to help. Z1720 (talk) 23:59, 29 June 2021 (UTC)
thread_title:  FA concerns 

message: Should Christoffel symbols be added?
\Gamma^1_{ij} = \begin{pmatrix}0 & 0 \\ 0 & -r \end{pmatrix}, \Gamma^2_{ij} = \begin{pmatrix}0 & \frac 1r \\ \frac 1r & 0 \end{pmatrix}
Angulon (talk) 01:25, 25 January 2023 (UTC)
thread_title:  Christoffel Symbols 

message: Proof of x= r×cos×phi
Etc. Yuthfghds (talk) 16:07, 27 May 2023 (UTC)
thread_title:  What about proofs 

message: The folium of Descartes is another nice application of polar coordinates and should perhaps be included in this article. Kontribuanto (talk) 21:18, 22 April 2024 (UTC)
thread_title:  suggested additional curve: folium of Descartes