Talk:Spheroid

surface area of spheroids

Can somebody please check the validity of the following formulae for the surface area of spheroids??

Prolate spheroid ( a > b ):

A = { 2πab²/ (a² – b² )^{1/ 2} }ln{(a + (a² – b² )^{1/ 2} ) / ( a - (a² – b² )^{1/ 2} )}

Oblate spheroid (a < b) :

A = { 4πab²/ (b² – a² )^{1/ 2} }arctan {( (b² – a² )^{1/ 2} ) / a}

Shameek

Is there a reference for the surface area formulas? I would like to verify them.

Nathalie —Preceding unsigned comment added by 145.94.17.181 (talk) 14:38, 10 February 2010 (UTC)

I agree, the current formulas look wrong. I only checked the oblate spheroid case. If you plug in semi-major/minor axes of Earth (a=6378km,c=6357km) to this formula, you get approximately 255E6 km^2 which is about half of the published surface area of 510E6 km^2 (which is relatively close to the spherical approximation). If you start with the more authentic looking formulas on https://en.wikipedia.org/wiki/Ellipsoid, and do some algebra you find that a sign has been flipped from positive to negative.

I think that you should use the following for the oblate spheroid case:

${\begin{aligned}S_{\text{oblate}}&=2\pi a^{2}\left(1+{\frac {c^{2}}{ea^{2}}}\cdot \operatorname {arctanh} (e)\right)&&{\text{where }}\quad e^{2}=1-{\frac {c^{2}}{a^{2}}}\quad (c<a),\\\end{aligned}}$

Note that if you change the inner plus sign (+) to minus (-), you get half the value.

Frank 108.211.109.173 (talk) 07:49, 2 September 2020 (UTC)

I can’t say where your calculations might have gone wrong, but I don’t find any problem with the results using formulas in the text. Your formulation is equivalent. Strebe (talk) 17:11, 2 September 2020 (UTC)

In oblate version when e is zero the surface should be a sphere $S=4\pi a^{2}$

In prolate version when a is zero the surface should be a sphere $S=4\pi c^{2}$

In both cases there seems to be a factor of 2 when in a sphere it should be 4. Astrojed (talk) 02:50, 2 November 2020 (UTC)

@Astrojed: The limit as e approaches 0 in the formulas given in the article for both oblate and prolate cases is 4πr², not 2πr², and therefore gives the expected result for the sphere.

Volume is indeed given by a single formula - check def of a and b

Another editor replacd the formula for the volume by this paragraph:

When the spheroid in question is oblate, the volume is ${\frac {4}{3}}\pi a^{2}b$ , where a represents the major axis of the ellipse which, when rotated about its minor axis, b, produces the oblate spheroid. When the spheroid in question is prolate, the spheroid is produced by the rotation of an ellipse about it's major axis, hence the volume formula becomes ${\frac {4}{3}}\pi b^{2}a$ , where b represents the minor axis of the ellipse which, when rotated about its major axis, produces the prolate spheroid. Hence, the volume of the oblate spheroid which results from the rotation of an ellipse about it's minor axis is always greater than the volume of the prolate spheroid which results from that same ellipse rotated about it's major axis; this is the case whenever a represents the major axis and does not equal b, which represents the minor axis.

This paragraph assumes that the parameters a and b are the major and minor semi-diameters of the ellipse which is the vertical section. However, in the formula given earlier in the article, a and b are the equatorial radius and the polar radius. With this nomenclature, indeed the formula is always (4π/3)a²b for any kind of spheroid. Incidentally this nomenclature is more sensible because it also gives *one* equation (implicit or parametric) for the surface, *one* equation for the area, and so on. All the best, --Jorge Stolfi (talk) 01:07, 28 December 2009 (UTC)

Tumor volume example

I moved the following example to grading (tumors) since it was far too specialized:

In experimental biology, tumor growth is approximated to take the shape of a spheroid. Often, cancer studies involve the implantation of tumors subcutaneously in mice. Such studies require a simple mechanism by which to evaluate tumor burden. One such method is for two blinded researchers to measure tumor dimensions length and width with calipers. The depth is not measured. Tumor volume in cubic millimeters can be approximated with the following formula:$Volume=0.52(Width^{2})Length$<ref>W. Su & Q. Wang: Inhibition of Human Prostate Cancer Growth and Prevention of Metastasis Development by Antiangiogenic Activities of Pigment Epithelium-Derived Factor. The Internet Journal of Oncology, 2007 Volume 4 Number 1</ref>

Moreover, in this layman's opinion that method is extremely crude (as it does not measure depth and assumes that the shape is a spheroid). However I retained the approximate formulas, in terms of radii and in termd of diametes (as in the example above). --Jorge Stolfi (talk) 02:25, 28 December 2009 (UTC)

Revised formulae

The above discussion bears witness to much confusion. If the discussion related to an oblate spheroid only it would make sense to use a,b on the spheroid as conforming to the 'standard' notation for the ellipse. For the prolate case however major and minor are reversed. I have changed notation to agree with current texts which consider both types of spheroid: in particular I agree with the Mathworld discussion. Typos permitting this article now agrees with mathworld. I have removed 'angular eccentricty' since the concept is not used at all in the current literature of mathematics, geodesy, map-projections (according to academic colleagues). The expressions are now written in conventional form.  Peter Mercator (talk) 22:55, 7 January 2012 (UTC)

Question Here...

Yeah, I don't know the freaking elite math grammar, so is tanh-1 e "tahn(-1)*e" or is it some other concept entirely? Because I'm getting improbably small surface areas by assuming the former. — Preceding unsigned comment added by 68.190.144.120 (talk) 23:35, 28 April 2014 (UTC)

Use $\textstyle \tanh ^{-1}e=\operatorname {artanh} \,e={\tfrac {1}{2}}\ln \left({\frac {1+e}{1-e}}\right)$, from the article on inverse hyperbolic functions. cffk (talk) 10:01, 29 April 2014 (UTC)

Merger proposal

I propose Oblate spheroid and Prolate spheroid be merged into this page, and turned into redirects. Much of the content is redundant except for the real-world examples of Oblate/Prolate spheroids.

67.252.103.23 (talk) 01:48, 8 June 2014 (UTC)

I think this is a good idea. cffk (talk) 03:29, 8 June 2014 (UTC)

I agree. Fgnievinski (talk) 00:05, 13 August 2014 (UTC)

Great idea. +mt 22:40, 1 September 2014 (UTC)

I agree. Bharat Singhvi 12:48, 5 September 2014 (UTC)

Agreed. Jaywilson (talk) 21:15, 17 November 2014 (UTC)

Yes BUT. Why stop there? The article Ellipsoid also covers the same material. I suggest that the three spheroid articles be merged into Ellipsoid using the figures therein and dropping some pretty pictures and possibly some of the uses/applications. We also need to include a discussion of nomenclature in the article, ie usage of spheroid/ ellipsoid of revolution/ ellipsoid as a function of time and subject area. Who will volunteer? — Peter Mercator (talk) 14:18, 18 November 2014 (UTC)

Disagree; in fact, portions of ellipsoid detailing ellipsoid of revolution would better be moved into spheroid. Fgnievinski (talk) 18:45, 18 November 2014 (UTC)

Peter, the key phrase is "Who will volunteer?" I think many editors realize that these pages need work but few are prepared to do the necessary grunt work. So if you're willing to put in the work, I'm sure that most will be happy to defer to your choices. A few thoughts: (1) Maybe include ellipsoidal coordinates, see Geodesics on an ellipsoid. (2) A standard convention for triaxial ellipsoids is a ≥ b ≥ c; so oblate and prolate ellipsoids are given by a = b > c and a > b = c, respectively. On the other hand if you're only considering ellipsoids of revolution, you would naturally choose a = b > c and a = b < c. cffk (talk) 15:07, 6 January 2015 (UTC)

 Done —David Eppstein (talk) 20:34, 21 April 2015 (UTC)

Sphere vs perfect sphere

I came here from a request at WikiProject math. Which is the better phrase, sphere or perfect sphere'? It depends on the context. In mathematics, a sphere is an ideal geometric object; it is already perfect and the perfect adjective is redundant. In colloquial parlace, outside of mathematical exposition, a sphere may a real world object that is fairly round and may be solid or hollow. In this case perfect sphere or most perfect sphere means a round object whose surface is remarkably close to that of a mathematical sphere. The usage of the perfect adjective is fairly common; searching for "perfect sphere" on Wikipedia nets 93 hits, including a number of our science articles and even in Sphere itself.

This article is firmly in the mathematical domain, so I don't see any need for perfect. But I think it is reasonable to include the colloquial term the first time sphere is used, to connect with lay readers. Perhaps something like

If the generating ellipse is a circle, the result is a sphere (commonly called a perfect sphere).

--Mark viking (talk) 22:54, 9 June 2016 (UTC)

I was thinking about adding the following paragraph to the article:

In common English usage, "sphere" may refer to objects that are only approximately shaped like mathematical spheres. For this reason, spheroids may be called "spherical" even though they are not in the mathematical sense. To distinguish mathematical spheres, they may be referred to as perfect spheres.

But then I realized that it really fit better at sphere. This article shouldn't need to address the linguistics of "sphere". I think it reads fine with or without "perfect" in front of "sphere". Ozob (talk) 01:32, 10 June 2016 (UTC)

I can see the points of both arguments. However, as Mark viking implicitly points out, when he uses the phrase, ". . . remarkably close to that of a mathematical sphere," this is a mathematics article. Hence, I agree with David Eppstein: the phrase "perfect sphere" is redundant in this article. It may be reasonable to refer to a sphere in non-mathematics articles as, "a sphere (commonly called a perfect sphere)." — Anita5192 (talk) 03:48, 10 June 2016 (UTC)

Additionally, per WP:OSE, just because there are many instances of the phrase "perfect sphere" in Wikipedia does not make it correct usage. I believe that every time this phrase occurs, it should be clarified parenthetically as Mark does above. — Anita5192 (talk) 03:55, 10 June 2016 (UTC)

We need not even resort to the mathematical argument. It's a matter of simple logic: If we say “very nearly spherical”, the phrase has no meaning unless the sphere referred to is perfect. Otherwise, the meaning would be, “very nearly a sphere which is not quite perfect”, which is simply a solecism. Using “perfect sphere” here is wrong, rather than a question of taste or even brevity. Strebe (talk) 08:19, 10 June 2016 (UTC)

To Anita and all above, you're reverted again, and here's why. I already discussed this at length and fully in the user's talk page, and also in that special "mathematics" page...now I'll transfer and paste all that I wrote onto here below:

hi. I don't like genuine redundancy either, but frankly you're just plain wrong with your comparisons of "wet water" and other things to the phrase "perfectly spherical". Astronomers and degreed people themselves have used that phrase. People who would never say the phrase "wet water". Not all spheres are necessarily perfect, is the point. What's the problem here?? And as I said, other WP articles have used that phrasing, as well as outside Reliable Sources. From another Wikipedia article that I had nothing to do with, these exact words:

"The Earth is not perfectly spherical but an oblate spheroid, so the length of a minute of latitude increases by 1% from the equator to the poles. Using the WGS84 ellipsoid, the commonly accepted Earth model for many purposes today, one minute of latitude at the WGS84 equator is 6,046 feet and at the poles is 6,107.5 feet. The average is about 6,076 feet (about 1,852 metres or 1.15 statute miles)."

And from an article on physics.stackexchange.com, these words:

"By this measure, the Sun is a near-perfect sphere with an oblateness estimated at about 9 millionths, which means that its polar diameter differs from its equatorial diameter by only 10 kilometres (6.2 mi)."

Are these scientists being "redundantly redundant" as you put it? Or do you see them saying "wet water"? (And that's just some examples; there are a lot more.) You accused me of "edit-warring" for simply not putting up with rude unwarranted reverts, for excuses that simply don't hold up, and keeping to 3RR. (One of my comments on the page was just an edit comment with no real edit...so I kept right at 3RR, and won't cross that.) YOU are edit-warring by imposing and removing a valid mod (provably valid mod), and clarity, that is NOT really "redundant"...as I kind of just proved with just a sample of places that rightly use the phrase that you have an issue against. The edit and qualifier was for clarity and is correct and used phrasing, and does not qualify for abrupt removal on the grounds of "redundant". That might be true if all "spheres" were considered always "perfect". Apparently not all of them are. Redzemp (talk) 21:22, 9 June 2016 (UTC)

In fact, all spheres are spherical. Otherwise they would be some other shape, not a sphere. That is the standard mathematical usage, and the spheroid article is a mathematics article. Your mention of astronomical bodies that are not actually spheres is irrelevant, because this is an article about mathematics, not astronomy. But as I said, you should take this to Talk:Spheroid. —David Eppstein (talk) 21:44, 9 June 2016 (UTC)

The phrase in question is not "spherical sphere" (THAT would be "redundant") but rather the phrase that you keep removing is "perfectly spherical" or "perfect sphere", and sorry, that simply is not redundant...as sources etc prove...as not all spheres are necessarily "perfect" is the point. Redzemp (talk) 22:20, 9 June 2016 (UTC)

In mathematics, this is false. It is possible to distinguish between different meanings of the word sphere (geometric versus topological, or in different metric spaces) but there is no such thing as an imperfect sphere. —David Eppstein (talk) 22:28, 9 June 2016 (UTC)

In "mathematics" or any other context, would you call the sun a "sphere" then? Even if it's not "perfect"? Would you call the earth a "sphere" even though it's not a perfect sphere? The sun and earth are both spheres, though "near perfect" or "not perfect". Why are they called "sphere" even if not 100% "perfect" in absolute circularity in every part? Yes we call the earth a "spherOID" but isn't the earth also called a sphere too? Maybe not in strict mathematics, I guess is your point. My point is that even you'd have to admit that the phrase "spherical sphere" is WAY MORE "redundant" than "perfectly spherical" or "perfect sphere". Remember, Wikipedia is NOT JUST for technical experts and semantical types, but also for average readers who may need elaboration and clarity. Again, OTHER Wikipedia articles dealing with distances etc, regarding the earth, say phrases like "perfectly spherical" etc... And so do some outside sources...written by degreed scientists. My point is that the phrase "perfectly spherical" is PROVABLY NOT the same as "wet water", as you were saying, with that comparison. The phrase "spherical sphere" would be more comparable to "wet water". As both those phrases are truly redundant and needless. Redzemp (talk) 22:36, 9 June 2016 (UTC)

The sun is definitely not a sphere. Its rotation makes its shape more of an oblate spheroid, even if one doesn't count solar flares, sunspots, and other irregularities. But also, the sun is a physical object, not a mathematical one, so asking whether it is a mathematical sphere is a context error, not even wrong. —David Eppstein (talk) 22:41, 9 June 2016 (UTC)

Here's the problem. I disagree with you in thinking that this article is strictly narrowly just a "mathematics article" in every single line or paragraph. And the context of the immediate paragraph and sentences in here were dealing with astronomy matters, the planet earth. (Even that means what, since isn't the whole universe mathematical in various ways anyway?) You say that this article is not about "astronomy". (As if astronomy has no math in it, which we all know that that's not true). But even so, how can you say that the Spheroid article is ONLY a "mathematics article" in every single line, sentence, or paragraph... when a paragraph about the PLANET EARTH (an astronomical thing) is in the article, etc? And also "gravity". Which also includes physics. All are connected. Such as: "Because of the combined effects of gravity and rotation, the Earth's shape is not quite a perfect sphere but instead is slightly flattened in the direction of its axis of rotation. For that reason, in cartography the Earth is often approximated by an oblate spheroid instead of a sphere. The current World Geodetic System model uses a spheroid whose radius is 6,378.137 km at the equator and 6,356.752 km at the poles." (And sorry, the sun and earth are "spheres" broadly, and are called that by scientists, when not being so overly-technical, and use the phrase "near perfect sphere" or "not a perfect sphere" etc. Both the sun and earth (and the moon too) are circular objects, even if not perfectly so on every side necessarily. Why does the word "spheroid" have the very word "sphere" in it? But anyway, you see the paragraph's wording dealing with astronomy matters. So even if this article is maybe mainly a "mathematics article", it's not 100% strictly just that. At least not totally in this paragraph in question. Redzemp (talk) 22:53, 9 June 2016 (UTC)

And that's all there is...and on the mathematics special page, some people who admit they are mathematically biased admit that "perfect sphere" can be used in this context here. He wrote:

....While this discussion should be on Talk:Spheroid perhaps placing it here will generate a greater response and may point to a larger issue that is of interest to the project. First of all, a sphere is a sphere is a sphere. A non-perfect sphere is not a sphere, so the adjective is mathematically redundant. However, to the general populace, the term sphere may refer to anything that is almost spherical (technically a spheroid) and for those who incorporate this fudge factor in their terminology, a perfect sphere distinguishes a mathematical sphere from the misnamed spheroids. The issue, as I see it, is whether or not a page that is devoted to the mathematical presentation should strictly use mathematical terminology even though the audience may not appreciate the mathematical nuances. I see the current (endless) discussion going on at Talk:Area of a disk as being essentially the same issue in a slightly different context. As an editor with a mathematical background, I do see, in myself, a definite bias towards precise, correct mathematical terminology ... but I do see this as a bias and feel that in some articles I should loosen up and not try to be as exact as I normally would desire to be. Bill Cherowitzo (talk) 03:51, 10 June 2016 (UTC)....

That was on the special page. Therefore, regardless of Anita and David... Reverted again, and Regards.... Redzemp (talk) 00:27, 11 June 2016 (UTC)

Redzemp, at this point you’re ignoring the preponderance of opinion on this page. That’s not a recipe for editing success. To repeat, “not quite a sphere” is nonsensical if “sphere” is taken as imperfect. Hence, there is no ambiguity about its meaning as is. Hence, adding “perfectly” is redundant. Redundancy is wrong. Meanwhile you have yet to demonstrate that anyone, ever, has been confused by the text as it stand. You are solving no problem, at the cost of thousands of words and the waste of many people’s time. What is your purpose here? Strebe (talk) 02:23, 11 June 2016 (UTC)

I just reverted your revert seconds ago. With the words "stop edit-warring and stop meat-puppeting, see my points in talk". Meaning, stop subbing for other people, in a tag-team fashion situation. You just dodged all the points and facts. There's no real "redundancy", insanely equating "perfect sphere" with "wet water" has been refuted. The discussion just started, and at least Mark kind of agrees. No real "consensus" yet. And your rude revert had no comment or explanation in it, against WP policy. I keep to 3RR. Thanks. Redzemp (talk) 02:26, 11 June 2016 (UTC)

Streb twice gives no comment explanation for his reverts, which is against WP policy. Ignoring the facts and points in my long comment and complaining about the length and words does not make an argument, it's just an evasion...and NO CONSENSUS WAS REACHED. Also Mark kind of agrees. Reverted. Redzemp (talk) 02:31, 11 June 2016 (UTC)

Redzemp claims I have given no rationale for my edits. I have. They’re up above, where they belong. Redzemp has completely ignored what I wrote, twice now.

Redzemp claims I am “subbing for other people, in a tag-team fashion”. I have no idea what “he” is talking about. I am the one who originally reverted the pointless injection of “perfect”, and I don’t know any of the other people involved. That and “meat-puppeting” are paranoid accusations.

Redzemp wants to imagine “his” edit takes precedence over what was in the article. It doesn’t. Every argument he wishes to make about the sanctity of his own edit applies to the original text as well.

Redzemp wants to imagine he makes a credible accusation of “edit warring” when he is the one who has reverted six times over the past 48 hours, overriding the judgment of three other editors, while refusing to wait until the conversation plays out here, on the Talk page, where it belongs. There is no emergency.

Strebe (talk) 04:38, 11 June 2016 (UTC)

Yes, Strebe, you were the first to revert, and you notice that in your first revert, no explanation or rationale was given. AGAINST WIKIPEDIA POLICY. And you continued with that, in your subsequent reverts. No rationale given...but only later and only in the talk page (later on), after other "expert editors" followed suit with wrong and refuted rationales of "wet water" redundancy claims, despite the fact that outside sources (not just other WP articles, but outside RS) say "perfect sphere" as well, etc. Again, to the general populace, the term sphere may refer to anything that is almost spherical (technically a spheroid) and for those who incorporate this fudge factor in their terminology, a perfect sphere distinguishes a mathematical sphere from the misnamed spheroids. Redzemp (talk) 07:34, 11 June 2016 (UTC)

hello. You may have had a valid point about wrong placement, in the paragraph about earth (possibly), but that's why the more respectful edit would be to simply re-locate to the more apropos paragraph, just before...but you didn't do that, because you just don't like or want the phrase "perfect sphere" in any sense, even when said to be "commonly called" etc...anywhere anyhow. That part is NOT repetitive, so that part (alone) I restored. So removing all of it was not called for. Trimmed yes, and better located, yes, but the parenthetical part was the whole matter in the first place. But you removed that too. And that's ownership activity, and hogging, mainly for "I don't like" reasons, but always given front excuses of "redundant" and "not accurate" or 'not needed' or whatever. But look up NO OWN.... Seriously. TOO many contributors on Wikipedia commit that, and always deny they're doing it of course. This is a wiki. This was MARK'S own wording... You have no business deleting stuff you don't like.... Non-valid removal restored. see article Talk... If the statement was not in the best paragraph, that's a valid point, but deleting it completely instead of relocating it better, with the excuse of "repetition" is not valid cuz YOU JUST DON'T LIKE "PERFECT SPHERE" anywhere in the article. That's really what it boils down to, despite Mark's comments and points on Talk. No consensus against putting Mark's compromise suggestion. Anyway, I did better placement...instead of wholesale removal. Redzemp (talk) 19:08, 12 June 2016 (UTC)

the refs were about the point of 'sometimes called'...unwarranted revert... For suppression and "I don't like" reasons....won't work, David....... We discussed this the other day, but obviously you won't even compromise coolly with no collaboration. Just with the attitude of "the words 'perfect sphere' will not exist in this article, in any way form or fashion, period". You have this big hang-up for some reason against the words "perfect sphere" even though they are sourced. And instead of admitting that you personally don't like the phrase, you and Strebe come up with all these front excuses and cop-out reasons to remove a valid and sourced point... And this was MARK's wording and suggestion (that even whittled down to instead of "commonly" called to "sometimes" called), but that's still not good enough for people who don't understand what the word "wiki" means, and that you don't own any article, no matter what your background is in "mathematics". Or how many Admins get fooled and suckered by this nonsense. I only go by references and true CONSENSUS...(even if the consensus is provably wrong, I still abide by it ultimately.) You and Strebe and Anita versus me and Mark and others don't a consensus make. Reverted, restored, and regards. Redzemp (talk) 20:41, 12 June 2016 (UTC)

Bad references

The references in this diff, which Redzemp is continuing to edit-war to include (as part of his larger war to qualify the word "sphere" with the meaningless adjective "perfect"), both fail our criteria for reliable sources.

physics.stackexchange.com is an open forum, and as such is a self-published source and in addition fails WP:ELNO #10.

the phys.org story uses the word "perfect" in a different context ("perfectly round", not "perfect sphere") and only in a headline. The usual rules of reliable sourcing are that information must appear in the actual body of a source, not the headline, because headlines are too often sensationalized to be reliable. And in this case it fails to source the claim that a sphere (the abstract geometric object) is "sometimes called a perfect sphere". —David Eppstein (talk) 22:01, 12 June 2016 (UTC)

Yes, David Eppstein, I agree that the ref is not so good, which is I added the other one phys.org, which is RS. You have a problem with that one too, because it doesn't say "perfect sphere" but "perfectly round", even though the rest of the page is in the context of a spherical sun, even if not actually using the word. (And if you're honest, you'd have to admit that.) But what do you think of "New Scientist.com"? Read these words here: "Now, an international group of engineers and craftsmen has gone him one better and built a pair of nearly perfect spheres that are thought to be the roundest objects in the world." (Click: https://www.newscientist.com/article/dn14229-roundest-objects-in-the-world-created/) You'll find some corny problem with that ref too, because in reality it's NOT about the source, as those are just convenient FRONT excuses that you (and your tag-team partner Strebe) are using, to hide the real reason of 'ME NO LIKE'. Even confronted with proof and good sources (here) that simply use that phrase that you think is so "redundant"... But the phrase, in whatever context, IS sometimes used by scientists and astronomers and physicists etc, "perfect sphere" etc. That new scientist source is not the only one either. Want another one? Ever heard of universetoday.com? These words: "The ones on the left are pulling towards the right. With all points pulling towards the center of the mass you would get a perfect sphere." Would you consider those "bad references"? (Click: http://www.universetoday.com/112805/why-is-everything-spherical/) I'm sure you'll find some cop-out reason to diss those too, like maybe how it doesn't apply or "doesn't fit", or whatever. Ignoring the point about "sometimes used"...in GENERAL. Anyway, Strebe the presumed co-owner of this article did another revert. I won't violate true 3RR. Redzemp (talk) 22:19, 12 June 2016 (UTC)

Your newscientist source may source the claim that non-spheres may be called "nearly perfect" but does not source the claim that spheres may be called "perfect". And AGAIN, it is about physical objects, while this article is primarily about abstract mathematical objects, so it is off-topic (wrong context) for claims about mathematical usage. And you have already hit at least 7RR today so your promise not to violate 3RR is too little too late. —David Eppstein (talk) 22:35, 12 June 2016 (UTC)

As I said, and true to form, which is why from now on I'll be ignoring you as you show no honesty or credibility on this particular matter, but just invested in a "no way will that phrase make it on this article" agenda. I'm sure you'll find some cop-out reason to diss those too, like maybe how it doesn't apply or "doesn't fit", or whatever. Ignoring the point about "sometimes used"...in GENERAL. Now you're coming up with LAUGHABLE AND TORTURED nonsense of ""nearly perfect" versus "perfect sphere" etc. Or maybe "this is primarily a mathematics article" even though some parts deal with physics and "earth" and "gravity". Seriously, man, you showed days ago what you're all about on here. Days from now, the edit goes back, with the refs. And of course you and Strebe, who ignore "no own" and "I don't like" all the time, will get in and disrespect as usual, with your edit-warring and nit-picking and wiki-battering and suppression. I'm done for now though. The point though is that the basic phrase of "nearly perfect" or "perfect sphere" WHICH YOU CLAIMED WAS "REDUNDANT" is "sometimes" used by authorities and people in these fields. Regards...... Redzemp (talk) 22:39, 12 June 2016 (UTC)

Please stay WP:CIVIL. Your personal attacks have no place here. —David Eppstein (talk) 22:45, 12 June 2016 (UTC)

True enough, but your actions and attitudes are not really all that civil here. How you (and Strebe) have been carrying on. About this minor thing, that is sourced and proven. It's not a cool attitude. What is the BIG DEAL of having (and in Mark's modified whittled down form even) and in parentheses, this simple sourced thing? I DON'T GET IT. You come up with all these reasons and problems and excuses, but I've addressed those. The phrase is sourced in GOOD references. I already conceded that you might have had a point about the open forum source, though the phys.org was a lot better, but these other two sources new scientist and universetoday are very good, and the matter is pretty clear there, and you're just blatantly dismissing them anyway, and LOOKING for ways to dismiss them. That's not all that cool or civil. Regards........ Redzemp (talk) 22:55, 12 June 2016 (UTC)

Compromise? I've showed it big time...whereas David and Strebe keep reverting to original, showing zero compromise.

I modified wording, changed it to make it "sometimes" instead of "commonly". I took MARK's suggested wording, of parenthetical, etc, from the Talk page. I looked for sources, and put better ones on the Talk page. I have gone out of my way to "compromise", big time. David flat-out lies when he says I haven't. On the notice board page. Unbelievable The only one "clearly not interested in compromise" is David Eppstein, because if you see what I've done I'VE BENT OVER BACKWARDS to "compromise". David's idea of "compromise" is don't change or modify it at all, and leave it the way it was. I provided good refs that show that "perfect sphere" is used by people in the field. David is unbelievable in saying that I am not interested in compromise, when he and Strebe are the ones who show ownership and "I don't like" attitudes and actions all over the place with ZERO compromise or give or take. Forgive my bluntness but he's been uncivil in his uncool actions and dissings of sourced mods and edits. Also this was MARK'S compromise and suggestion, that I tried putting in (with sources) that get rudely removed regardless. This is what I wrote and proved in the article talk page....

"New Scientist.com"?

Read these words here: "Now, an international group of engineers and craftsmen has gone him one better and built a pair of nearly perfect spheres that are thought to be the roundest objects in the world." (Click: https://www.newscientist.com/article/dn14229-roundest-objects-in-the-world-created/)

universetoday.com?

These words: "The ones on the left are pulling towards the right. With all points pulling towards the center of the mass you would get a perfect sphere."

Would you consider those "bad references"? (Click: http://www.universetoday.com/112805/why-is-everything-spherical/) I'm sure you'll find some cop-out reason to diss those too, like maybe how it doesn't apply or "doesn't fit", or whatever. Ignoring the point about "sometimes used"...in GENERAL.

Anyway, You see the sources? And I took the time and effort to make points and show proofs etc, making effort to discuss and make the case, and instead of appreciating any of that, David disses and belittles it and accuses me of "textwalling" putting a negative dishonest spin on everything. But look at what happened. That shows that the statement is justified and "sometimes used" by reliable sources, that David simply does not want in, regardless of sources. He'll find some excuse to diss or dismiss those valid sources anyway.. Showing NO compromise at all. I've tried. He's pot-kettle-black on this, big time.

I've done all I can to show compromise, from taking Mark's suggested wording. And then even changing that from "commonly used" to "sometimes used". Tell me. And then finding sources. One was not that good, so I got another one. And now I found two VERY good ones. Tell me. Where in any of that did I show "no compromise"?

But David keeps removing and reverting all the time, to bring it back to the original with no addition whatsoever. Tell me. Where is David showing any compromise with that? And he has the nerve to talk about "civility"? And "no compromise". That's why I made the blunt statement that I will be ignoring him, because he showed clearly that he has no real credibility on this (along with Strebe), but is blatantly dishonest on this, from start to finish. I have solid proof that I've showed BIG TIME "compromise". He said I showed none. (???) I have solid proof that David showed literally ZERO compromise. Yet he's making out like he's the cool collaborator and compromiser, when he'd been nothing of the kind. The proof is in the edits and in the talk page comments. Regards. Redzemp (talk) 12:22, 13 June 2016 (UTC)

The solid?

What is the name of a solid whose surface is a spheroid? This should be mentioned in the opening two sentences. Koro Neil (talk) 03:17, 22 February 2021 (UTC)