Talk:Cylinder

Cylindric section equation source?
The equation for the semi-major axis a in the section Properties/Cylindric sections appears to be wrong. With the current definition, it would imply that the semi-major axis becomes infinite if the cylinder is aligned with the normal of the secant plane. If the equation is changed to a=r / cos(alpha), then the semi-major axis becomes the radius of the cylinder when the cylinder is normal to the plane. What is the source of this equation and is the equation for eccentricity also incorrect?Grumbins (talk) 04:53, 30 June 2022 (UTC)

definition?
Definition, does the parallell lines need to to be line segments of equal length?
 * Which parallel lines? Are you referring to &sect;Cylindric sections?  In that case, the line segments would be be the height  $h$ of the cylinder. Andy Dingley (talk) 10:27, 8 March 2017 (UTC)

definition error
The introduction is wrong. Cylinders are not limited to objects having a surface that is "a fixed distance from the axis" [of the cylinder] - this applies only to a circular cylinder. Can the last author please fix this and any other inconsistencies.

Thanks,

2001:569:737B:AD00:D421:2F70:F52F:CCBE (talk) 18:39, 24 November 2015 (UTC)

Typo? cylinder with arbitrary axis
i think this line: $$B =-x\cos(\theta)\sin(\phi)+y\sin(\theta)\cos(\phi)+z\cos(\phi)$$

should actually be: $$B =-x\cos(\theta)\sin(\phi)+y\sin(\theta)\sin(\phi)+z\cos(\phi)$$

Avi --185.46.212.75 (talk) 11:16, 15 June 2016 (UTC)

Requested Move discussion in progress.
There is a discussion going on at the Talk Page for "Cylinder" to move that page to Cylinder (disambiguation). It is implicit in the proposal that this page would move to Cylinder, but that is not formally part of the proposal. You may want to participate in that discussion. --MrStoofer (talk) 11:10, 9 December 2016 (UTC)
 * As the move has been done, the (closed) discussion is now at Talk:Cylinder (disambiguation). D.Lazard (talk) 10:04, 8 November 2017 (UTC)

Move discussion in progress
There is a move discussion in progress on Talk:Cylinder which affects this page. Please participate on that page and not in this talk page section. Thank you. —RMCD bot 21:46, 9 December 2016 (UTC)
 * As the move has been done, the (closed) discussion is now at Talk:Cylinder (disambiguation). D.Lazard (talk) 10:05, 8 November 2017 (UTC)

"Rod (geometry)" listed at Redirects for discussion
A discussion is taking place to address the redirect Rod (geometry). The discussion will occur at Redirects for discussion/Log/2021 March 8 until a consensus is reached, and readers of this page are welcome to contribute to the discussion. CiaPan (talk) 20:36, 8 March 2021 (UTC)

"Rod (shaft)" listed at Redirects for discussion
A discussion is taking place to address the redirect Rod (shaft). The discussion will occur at Redirects for discussion/Log/2021 March 9 until a consensus is reached, and readers of this page are welcome to contribute to the discussion. Adumbrativus (talk) 06:09, 9 March 2021 (UTC)

The page Cylinder is incorrect.
According to James Tanton a cylinder is a made from creating a base shape on a plane, making a congruent shape on a parallel plane and connecting each edge/point to the corresponding edge/point on the other base. This is not the definition that is on the Cylinder page.

The source for this is: [Https://www.youtube.com/watch?v=XS4xSytnAm8 https://www.youtube.com/watch?v=XS4xSytnAm8]

James Tanton also mentions this in his Geometry course, sold at: https://www.thegreatcourses.com/courses/geometry-an-interactive-journey-to-mastery. Pigly3 (talk) 01:44, 6 December 2023 (UTC)


 * There are several related concepts of 'cylinder' used in mathematics, and which one is more convenient depends on context. –jacobolus (t) 03:38, 6 December 2023 (UTC)
 * Tanton's definition is equivalent to that of the article's first paragraph. —Tamfang (talk) 07:14, 14 December 2023 (UTC)

Incorrect height designation in the figure
In the figure "A solid elliptic cylinder with the semi-axes..." height h indicates the length of the side of the cylinder, which is greater than the real height by 1/cos(φ) times, where φ is the angle of the cilinder axis to the normal to the base AAPoul (talk) 02:36, 5 May 2024 (UTC)


 * In this particular case, it's clear that the side of the cylinder is perpendicular to the base. This could perhaps be pictured/stated more clearly. –jacobolus (t) 06:08, 5 May 2024 (UTC)
 * [[file:Zylinder-schief-ellipt.png|thumb]]
 * The caption in the article says that it is an elliptic cylinder that is represented, but most readers will see a circular cylinder with oblique plane sections (that are therefore elliptic). So, the image is not well suited for illustrating the text, and is more confusing than useful. In commons, the only image that I have found that represents an elliptic cylinder is the one that is displayed here, but its labels do not correspond to this article. So, I'll edit the caption, but I am not very happy with this solution. D.Lazard (talk) 08:43, 5 May 2024 (UTC)