Talk:Cartesian coordinate system

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
WikiProject Mathematics (Rated B-class, Top-importance)
WikiProject Mathematics
This article is within the scope of WikiProject Mathematics, a collaborative effort to improve the coverage of Mathematics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Mathematics rating:
B Class
Top Importance
 Field:  Geometry
One of the 500 most frequently viewed mathematics articles.
Wikipedia Version 1.0 Editorial Team / v0.7 (Rated C-class)
WikiProject iconThis article has been reviewed by the Version 1.0 Editorial Team.
C-Class article C  This article has been rated as C-Class on the quality scale.
B checklist
 ???  This article has not yet received a rating on the importance scale.
 
Note icon
This article is within of subsequent release version of Mathematics.
Taskforce icon
 This article has been selected for Version 0.7 and subsequent release versions of Wikipedia.

first you go[edit]

first you go on the y axis then x axis or roll out of bed and stand up. go to the place then go up the alevator —Preceding unsigned comment added by 75.186.127.110 (talk) 20:07, 13 April 2009 (UTC)

The note that this needs more references is probably unwarranted. Do you want people referencing their textbooks from junior high? — Preceding unsigned comment added by 124.148.103.206 (talk) 09:12, 20 March 2014 (UTC)

The 3rd dimension[edit]

All rights reserved, without prejudice (BioPseudo (talk) 08:01, 28 January 2017 (UTC)) BioPseudo (talk) 08:01, 28 January 2017 (UTC)

Orientation of the right hand in the illustration[edit]

For maximum clarity, the hand should be palm up with the index finger pointing away from the viewer, and the perspective should be looking at the hand from a three-quarter above view. In this way, the X axis will increase positively to the right, the Y axis positively going away from the viewer, and the Z axis positively going up. As it stands, the illustration is very confusing when trying to relate it to the conventional directions a 3d system is displayed in. (I'm speaking of the Y horizontal increasing away from the viewer, Z vertical convention as opposed to the Y vertical, Z towards the viewer convention. The current illustration depicts neither.) --HarmonicSphere (talk) 15:15, 23 October 2012 (UTC)

Maybe the user HarmonicSphere would benefit from a short video. But this would be a little complicated, since someone will have to draw the axes onto the video of the hands. Solo Owl 16:36, 5 February 2017 (UTC)

I agree that the illustration of the right-handed axes represented by the fingers ought to conform with the figure above it. But I disagree that the position of the hand ought to change, rather the axes in the figure ought to change to conform to the hand shown in the illustration. This is because it is much easier to put one's fingers and hand in the position shown in the illustration. Being able to easily put one's hand into a representative position assists with comprehension of the handedness concepts. Otherwise, one becomes distracted by attempting anatomical contortions and the potential derogatory implications that a vertical z-axis position may convey. Dawnvawn (talk) 20:19, 24 November 2015 (UTC)

2d Right Hand Rule ambiguous[edit]

The text currently in concern is: "Placing a somewhat closed right hand on the plane with the thumb pointing up, the fingers point from the x-axis to the y-axis, in a positively oriented coordinate system". This text is ambiguous, because a "somewhat closed" hand is not defined, and I am not able to reproduce the positive x,y orientation using this. It's also unclear what axis the thumb is aligned to. A picture might be helpful, but this article has enough pictures already. IsmAvatar (talk) 00:05, 28 February 2008 (UTC)

Actually I would go a step farther -- "handedness" is a concept that is only properly applied to a 3D system, not a 2D system. The concept of right- or left-handedness doesn't apply to a 2D system at all without the context of a third axis. For either of the two possible 2D orientations (x right / y up or x right / y down), both a left- and right-handed 3D system could be created by adding a third axis "into" or "out of" the plane. —Preceding unsigned comment added by 98.220.184.209 (talk) 22:04, 28 August 2008 (UTC)

I have read in more than one linear algebra text that left- and right-handedness do not apply to two-dimensional systems. At best, the article assumes that the handedness of a 2D system depends on the orientation of the "thumb" being up, and at worst, the concept of handedness is meaningless in 2D. By assuming the thumb is pointing upward in determining an orientation for a 2D system, a third axis is being added implicitly to the logic.

To tell the truth, the subsection of the article headed "Orientation and handedness / In two dimentions" is not just confusing — it is flat-out wrong.
  • The two paragraphs attempting to describe the x and y axes with hands manage to give the exact wrong answer. Perhaps someone's hands are uniquely different, or more likely, someone has right-left dyslexia.
  • "When pointing the thumb away from the origin along an axis towards positive, the curvature of the fingers indicates a positive rotation along that axis." This is interesting, but totally inadequate. What is meant by "along that axis"? Which fingers' curvature is to be considered?
  • The last sentence contradicts itself. Why mention "any two axes" when only two axes exists in a 2D system? I think they meant to say "either axis".
  • The illustration really belongs in the next subsection.
As others have pointed out, a right-hand rule for two axes is unnecessary, as well as confusing and burdensome to some readers. I am tempted to rewrite it (if I can figure out what to do with the illustration), but it is time to take a shower and get my dinner. Solo Owl 17:11, 5 February 2017 (UTC)

Rectangular coordinates[edit]

This name redirects here and should be mentioned at the start of the article.--عبد المؤمن (talk) 21:31, 26 October 2014 (UTC)

Main Image Missing Signs[edit]

The main image (this one: https://en.wikipedia.org/wiki/File:Cartesian-coordinate-system.svg) shows without signs in my screen. This is a bit weird, since clicking on the image in the link I provided results in a correct image. If this helps, I am using Chrome and Windows 7. If other people are having this issue it should be fixed.

--Uncronopio (talk) 13:00, 8 September 2017 (UTC)

2^2 + 2^2 = 8 not 4[edit]

In the image of the first circle, x^2 + y^2 = 8 not 4. — Preceding unsigned comment added by 76.103.144.197 (talk) 17:23, 1 November 2017 (UTC)

The circle does not pass through the point (2,2), so this does not make any sense. A circle of radius r centered at the origin has the equation x2 + y2 = r2, and since this one has radius 2, the equation given in the figure is correct. --Bill Cherowitzo (talk) 17:32, 1 November 2017 (UTC)

Polar coordinates[edit]

In History: "Many other coordinate systems have been developed since Descartes, such as the polar coordinates for the plane, and the spherical and cylindrical coordinates for three-dimensional space.". Was this since, or at about the same time. And why is it relevant? Charlie2018 (talk) 20:20, 27 November 2017 (UTC)

History[edit]

This seems to be vary lacking in the history and development of the actual coordinate system itself. So lets say for example I was wanting to learn about the development and history of ideas behind the Cartesian system, this article wouldn't help me very much. Is there not a lot of information available about Descartes' thought process, methodology, his reason for needing to develop such a system? I think that inclusion of that information to the History section would be very helpful.Tazdn2 (talk) 16:56, 16 February 2018 (UTC)

This is not that easy to do. Most of the basics of a Cartesian coordinate system were not introduced by Descartes. The modern formulation of these ideas were developed over the years by people who were trying to make what Descartes wrote understandable to the rest of the world. Perhaps looking at Boyer's History of Analytic Geometry would help here. --Bill Cherowitzo (talk) 18:17, 16 February 2018 (UTC)

"Axis" or "axes"?[edit]

I'm confused seeing "The coordinates are often denoted by the letters X, Y, and Z (or x, y, and z), in which case the lines are called the X-, Y-, and Z-axis, respectively. Then the coordinate planes can be referred to as the XY-, YZ-, and XZ-planes." Why is "axis" used instead of "axes"? Or why is "planes" used instead of "plane"? Also, I saw in some other articles "x-, y-, and z-axes". Who knows which is correct?XhXia (talk) 05:36, 11 July 2018 (UTC)

English rules of grammar can be confusing and while I am no expert, I think I can explain this one. The key is the word "respectively". What that word does is to change the clause from a group description (for which "axes" would be appropriate) to a listing of the individual members of that group (each of which is singular, hence "axis" is used). Notice that when the coordinate planes are talked about, they are talked about as a group, so "planes" is the correct form. Had they been dealt with individually (either with a "respectively" or some other construct) such as "Consider the XY- or the XZ-plane ..." the singular form is needed. I hope this helps. --Bill Cherowitzo (talk) 16:36, 11 July 2018 (UTC)
I see. Thank you very much. XhXia (talk) 12:41, 12 July 2018 (UTC)
Retrieved from "https://en.wikipedia.org/w/index.php?title=Talk:Cartesian_coordinate_system&oldid=934161274"