Talk:Spheroid

message: 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^2b , 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^2a , 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)
thread_title:  Volume is indeed given by a single formula - check def of a and b 

message: 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)LengthW. 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
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)
thread_title:  Tumor volume example 

message: 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)
thread_title: Revised formulae

message: 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)
replies: text: Use \textstyle \tanh^{-1}e = \operatorname{artanh}\, e = \tfrac12\ln\left(\frac{1+e}{1-e}\right), from the article on inverse hyperbolic functions. cffk (talk) 10:01, 29 April 2014 (UTC)
thread_title: Question Here...

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

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

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

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

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

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

text:  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)
thread_title:  Merger proposal 

message: The references in this diff, which  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)
replies: text: 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)
replies: text: 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)
replies: text: 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)
replies: text: Please stay WP:CIVIL. Your personal attacks have no place here. —David Eppstein (talk) 22:45, 12 June 2016 (UTC)
replies: text: 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)
thread_title:  Bad references 

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

message: 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)
thread_title:  The solid?