Talk:Coordinate system

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Just to explain why I removed Siting Huo's edit (Coordinate System in GIS): it's too specific, it doesn't belong in a general article on coordinate systems. I tried looking later in the page for a place where it should go, but the whole article is on too much of a general level for that. Perhaps "Coordinates in GIS" should be a separate page, or perhaps it should be in Map Projection. — Preceding unsigned comment added by Jim Pivarski (talk • contribs) 23:47, 31 January 2013 (UTC)Reply

I'm not sure what would be the best way to write the idea correctly on the basic description, but what about non-number coordinates? A great example would be Chess Coordinates, where "E2" defines a position in an R^2 universe. — Preceding unsigned comment added by 24.188.55.241 (talk) 13:48, 1 November 2013 (UTC)Reply

Yes, the assumptions of "real numbers on manifold" is all together too restrictive. Don't forget about dates, either -- they supply a coordinate system over time, but we don't usually encode those cordinates with real numbers. The other thing about coordinates is that you typically do not want to add them together. We don't scale coordinates either -- how would you scale "Janary 3rd, 2010". Instead, you typically want to take differences, or measure distances or angles between points with specified coordinates. Even in chess, we might want to know how many moves it takes to get a given piece to a given square, but we never add coordinates. Only the difference between coordinates can be added in a way that makes sense. Sometimes people assert that these distinctions are obvious and don't need to be spelled out until you get to more abstract things like a principal homogeneous space, but maybe we should be more up front about the differences between coordinates and how we move between them. Uscitizenjason (talk) 14:59, 28 July 2023 (UTC)Reply

You may want to add a section for "how to add coordinates to a wikipedia page" or something, because right now I'm having trouble finding out how to add coordinates, and I'm sure other people are to. 69.18.241.212 (talk) 03:10, 3 February 2018 (UTC)Reply

This is the talk page for an article about the mathematical concept. If you want help editing a Wikipedia article, see WP:MOS, WP:MOSMATH, or WP:HELP.—Anita5192 (talk) 05:08, 3 February 2018 (UTC)Reply

Hello all! I noticed that this article covers various examples of coordinate systems, and in the end mentioned the concept of "intrinsic equations", which made me wonder: Would it be appropriate to explain in this article the reasons why some systems are more suited for describing in coordinate, and why others are not as well suited for coordinates? How does this relate to "analytic" versus "synthetic" geometry? Also, would it be possible to make some categorization scheme that describes the relations between the different types of coordinate system? For example, I noticed that the article mentioned, in the "Other commonly used systems", Plucker Coordinates before homogeneous coordinates, of which they are subset. I didn't want to make any major changes before seeing what other thought. Thanks for taking the time to read this comment! JonathanHopeThisIsUnique (talk) 21:46, 5 March 2018 (UTC)Reply

Edits by Mikus have been reverted three times and I would like to explain why in more detail than the edit summaries allow. First of all, the Schaums outline series that is being used here as a reference is a time honored series of study guides in various subjects. They are strictly formatted for the purpose of helping students master the fundamentals and while they do not intentionally get things wrong, their stripped down and simplified approach can mislead serious students without significantly hurting their intended audience. They are not considered authoritative by the professional community and are often the butt of many jokes among educators. As an example in this article, "a linear coordinate system is a graphical representation of ...", while presenting students with a visual handhold, is technically wrong. This confusion between the coordinate system and its graphical representation will not do too much harm, but they are clearly different things (consider the fact that the coordinate system can exist without having a corresponding drawing). Another example of an incorrect simplification is given by Schaums' treatment of arrows. Schaums declares that the positive direction on a number line is indicated by an arrow. While this is certainly true sometimes, it is far from universally accepted. Often no arrow is ever drawn and sometimes an arrow just indicates that a line is to be extended in the arrow's direction. These considerations are due to the illustrator's preferences and are not part of any mathematical definition. A final comment about the heading for this section. This is an article about coordinate systems and calling the first example of such a linear coordinate system is quite pedantic and presupposes that the reader knows what a coordinate system is already. By calling the section number line, the reader who is unfamiliar with the topic has a chance of connecting to an idea that might be vaguely remembered. This is therefore a much better heading and shows some appreciation for the difficulties that a reader might be having with a mathematics article. --Bill Cherowitzo (talk) 19:51, 30 November 2018 (UTC)Reply

Wcherowi, (1) I agree on "a linear coordinate system is a graphical representation of ...", and it can be rephrased. (2) Schaums is not the only series that advocates usage of arrowhead to indicate positive direction. In fact, books written by different authors within Shaums series may show different treatment of arrowheads. I am not to believe that the way arrowhead is pictured is left to a mere illustrator, this would be akin leaving a big red button to a monkey. This is a very specific part of math notation, and it can be correct or not. Having two arrowheads makes no sense whatsoever. Its proponents say that arrowheads mean that the line goes indefinitely in both directions, but it would do just the same without arrowheads, this is standard geometric convention. Put a terminating point or tick, and then it is a ray or a segment, with terminators. Unterminated, it goes indefinitely. So, arrowheads are not helping. On the other hand, what if one wanted for the numbers to grow to the left? How do you depict this? With one arrowhead it is quite simple, just draw it on the left side. But even if one to agree that drawing none, one or two arrowheads is up to an illustrator, we must either present all three options or choose the one that makes most sense, which is one arrowhead. (3) Naming a chapter linear coordinate system is not pedantic, but in fact follows the style of the article. Number line is mentioned in the chapter, so I see no harm being done. Also, I suggest merging "number line" and "real line", but this is for another day. Anyway, what could be discussed and edited and fixed, you prefer to simply remove. Uncool. Mikus (talk) 23:05, 30 November 2018 (UTC)Reply

I find your comments on arrowheads to be confused and contradictory. You first claim that other Schaums authors may use them differently and then claim that this is a standard geometric convention. You claim that having arrows in both directions is meaningless and then claim that there are proponents of this convention. These arrowheads belong to the illustration and are not part of any mathematical notation. They are not necessary to indicate the orientation of the number line and can be simply done away with by labeling any other point (with a signed real number) after the origin has been selected. They are part of the art of illustration, not the mathematics. --Bill Cherowitzo (talk) 04:08, 1 December 2018 (UTC)Reply

For example, the Cartesian coordinate system in 3D can be left or right handed, and have different vectors pointing up. Ex: https://pbs.twimg.com/media/DTbWux8WkAUOZZx?format=png I think this is worth mentioning in the article, somewhere. Aaronfranke (talk) 23:02, 19 September 2019 (UTC)Reply

In my opinion, the number line is a just a part of the Cartesian coordinate system. — Preceding unsigned comment added by Koitus~nlwiki (talk • contribs) 13:31, 12 January 2020 (UTC)Reply

The second sentence of the intro

The order of the coordinates is significant, and they are sometimes identified by their position in an ordered tuple and sometimes by a letter, as in "the x-coordinate".

is contradictory, it first claims that the order of the components is relevant and then proceeds to list one order dependent and one order independent way to write coordinates. If you're using standard tuple notation, then of course the order matters and, because it's very concise and efficient, this is the most common way to write coordinates when you're using them extensively.

But the second mentioned case is that you're using variables (or any other way to tag the values, like (29.9765° N, 31.1314° W)), which is more common if you're using the coordinates more casually, and in this case there doesn't even have to be an order. Using geographical coordinates as an arbitrary example, you could have a variable or function whose value is the latitude and one whose value is the longitude, without them being in any order, and they still form a coordinate system. An improvement could look something like

The coordinates of a coordinate system are often referred to and distinguished using variables like x and y, or they are taken to form a tuple, distinguishing them by their order.

This removes the contradiction and it seems to me like it will still conveying the intent of the original sentence, which is generally showing how coordinates are commonly specified in different ways and also more specifically mentioning x-coordinates as example so readers will know that this is the right article for them. I'm writing here because the second part of my sentence seems a little vague (how are they distinguished by their order?). If noone has a better idea, I will go ahead and change it. Ninjamin (talk) 21:41, 14 June 2025 (UTC)Reply

Good catch. I have edited the article in the line of your remarks, with a phrasing that is simpler than yours an closer to the previous version. D.Lazard (talk) 08:26, 15 June 2025 (UTC)Reply

The article doesn't seem to provide a formal definition of a coordinate system, mentioning only that it's a "system" that "uses" numbers to determine "positions." I think a "Definition" section that provides a formal definition would be nice, since "system" is not mathematically rigorous and "position" can be taken to mean only elements of an affine space. I'm not an expert here so I'm not going to add anything, but would "a function that maps elements of a space (e.g., a vector space) to ordered n-tuples, called the coordinates of that element" perhaps be a definition used in literature? Cloud 223 (talk) 07:21, 18 July 2026 (UTC)Reply

Why don't you do a literature survey and find a few sources discussing the topic. (Although frankly, I don't think an extremely formal definition is going to be that helpful for almost any reader; the article is, and should be, pitched at a pretty general audience who will find such a definition confusing and unnecessary, and anyone with advanced mathematical background isn't going to have a particular difficulty imagining a definition at whatever level of rigor they like, for whatever context they are in. But it could conceivably be discussed toward the bottom of the page.) –jacobolus (t) 20:13, 18 July 2026 (UTC)Reply