User talk:DVdm

— Welcome to my talk page — Please leave new comments at the bottom and sign them with tildes (~~~~) at the end. I'll respond here. If I have left a message on your talk page, please respond there. I'll try to keep an eye on it. If you think I forgot to check don't hesitate to remind me here. "They never be working' when they oughta should." "Watch out where the Huskies go, and don't you eat that yellow snow." "Remember there's a big difference between kneeling down and bending over." "Jazz is not dead, it just smells funny." "Everybody in this room is wearing a uniform, and don't kid yourself." vn-349This user talk page has been vandalized 349 times. — Canard du jour — If I come back as an animal in my next lifetime, I hope it's some type of parasite, because this is the part where I take it easy. — Jack Handey This user has been on Wikipedia for 19 years, 2 months and 13 days. This user has earned the 100,000 Edits Award.

Gamma function edits

Thank you for removing my edit. I just noticed the term 'translated'.Your Local Math Geekd (talk) 20:40, 21 May 2020 (UTC)

Removing external links

I just had external links removed from a page for basically no clear reason. Years ago I would add the very same links to an info database and they were not removed. I just wish this type of action would not happen here. It limits the users' access to useful data. SourceCodeX (talk) 13:45, 26 May 2020 (UTC)

@SourceCodeX: as I said in my edit summary ([1]) and on your talk page, please have a look at wp:ELNO item 11: "Blogs, personal web pages and most fansites (negative ones included), except those written by a recognized authority." I really like the webpage, but it's no good for Wikipedia. Alas. - DVdm (talk) 13:50, 26 May 2020 (UTC)

The external links removed were to a database of finely written music reviews. Writers not only contributed there but their reviews were featured on allaboutjazz.com and were paid reviewers for allmusic.com. This is not a fan site but holds stellar reviews of many genres by music experts and they are recording musicians as well. Users of Wikipedia would appreciate that kind of information at the links removed. Why hasn't anyone here removed Al Garcia's link on Jazz Fusion which blatantly seeks sales of his own music? Please explain that. The links you removed were contributions by recognized authors of the genre. We were paid for our knowledge but Wikipedia members seem to see otherwise. I guess I am not a recognized member of the editing "club" here, which explains everything. SourceCodeX (talk) 14:07, 26 May 2020 (UTC)

See wp:otherstuffexists. It's not because something (possibly bad) is done in some articles, that it can also be done in yet another article. If it has survived in the other articles, it probably was by wp:CONSENSUS, so if you would like to undo it in some other article, the best place to go is the article talk page, and propose to undo it there. For your speciific addition of the website in these two articles, there clearly is no consensus (yet). If you would really really really like to add an external link to that site, the place to go is the article talk page Talk: Mahavishnu Orchestra (and later perhaps also Talk:Jazz fusion) and propose to add the link to the external links section. You can put a reference to this section here (User talk:DVdm#Removing external links). Good luck. - DVdm (talk) 15:33, 26 May 2020 (UTC)

Dawkins

Hey mate you left a warning on my page. I understand the issue but i have received no discussion from the individual reverting my edits. No one else has objected, to the objective facts i have included.

As I am the one trying to engage and not the one reverting, can I ask why you have chosen to report me like this? — Preceding unsigned comment added by Permareperwiki1664 (talk • contribs) 15:13, 28 May 2020 (UTC)

Please sign all your talk page messages with four tildes (~~~~) — See Help:Using talk pages. Thanks.

@Permareperwiki1664: I have not reported you. I have warned you. Getting reported and likely blocked for edit warring is what will happen next. What you need is wp:CONSENSUS on the article talk page. See wp:NOCONSENSUS: "In discussions of proposals to add, modify or remove material in articles, a lack of consensus commonly results in retaining the version of the article as it was prior to the proposal or bold edit." - DVdm (talk) 15:22, 28 May 2020 (UTC)

Coveriance

My statement on Covariance was correct. Covariance has no physical meaning. This is not debatable. I will keep removing your statement as it is clearly false. I suggest that you read this paper by:

J. D Norton https://www.pitt.edu/~jdnorton/jdnorton.html

http://www.kevinaylward.co.uk/gr/covariance_relativity.pdf

J. D. Norton has a Ph.D. in The History Of Relativity.

My own summary of what the POR is also here

http://www.kevinaylward.co.uk/gr/postulate1/postulate1.html — Preceding unsigned comment added by Kevin aylward (talk • contribs) 06:03, 4 June 2020 (UTC)

Please put new talk page messages at the bottom of talk pages and sign your messages with four tildes (~~~~) — See Help:Using talk pages. Thanks.

@Kevin aylward: Our own books and articles and websites don't count as wp:reliable sources. Our own credentials are of no importance. wp:Original research, even when based on proper sources, is not allowed on Wikipedia.

If an edit of yours ([2]) is reverted ([3]), then you should go to the talk page and, with reliable sources at hand to directly support the change, propose to the other editors what you want to do, and try to get a wp:CONSENSUS. See wp:BRD. If you can't get consensus, then nothing changes to the article —see wp:NOCONSENSUS. wp:Edit warring will get you blocked. - DVdm (talk) 08:56, 4 June 2020 (UTC)

One could well do without the condescending attitude mate. I am well aware of wikki policies. The reference to my article was to provide a deeper background to the issue in the event that individuals were unable to understand the clear refutation, by experts, of the claims made in the article. The actual authority for my statement was clearly that of one of the leading experts on the History of Relativity. The pdf link is an article written by Norton, not me. Norton goes into explicit depth as to what Covariance is, and why it is often confused, with detailed references to noted mathematicians that explain the point in detail. It is not debatable. That is, any set of equations may be put in Covariant form. Covariance is not a POR, and the statement that the POR is a statement about the form of equations is false. Period.

Although, as noted by Norton, Einstein was confused, Einstein still stated this:

Special principle of relativity: If a system of coordinates K is chosen so that, in relation to it, physical laws hold good in their simplest form, the same laws hold good in relation to any other system of coordinates K' moving in uniform translation relatively to K.

— Albert Einstein: The Foundation of the General Theory of Relativity, Part A, §1

Is not equivalent to:

“the requirement that the equations describing the laws of physics have the same form in all admissible frames of reference.”

This should be trivially obvious. One is a statement on real physics, one is a statement on mathematically formulism.

Kevin Aylward 12:36, 10 June 2020 (UTC) — Preceding unsigned comment added by Kevin aylward (talk • contribs)

Again, please sign your talk page messages with four tildes (~~~~) — see Help:Talk pages#Identifying yourself.

I also pulled your above comment out of mine — see Help:Talk pages#Replying to an existing thread: "Add your comment below the last entry in the discussion. If you want to respond to a specific comment, you can place your response directly below it." You placed your comment in the middle of mine.

If you find my warning about wp:consensus and wp:edit warring condescending, you better read the policies and guidelines again. A comment like your "I will keep removing your statement as it is clearly false" will get you blocked in no time. - DVdm (talk) 14:01, 10 June 2020 (UTC)

You can still keep you opinions to your self mate. They are worthless.

I suggest that you read the Wikki article on Kretschmann, of which I have had no part off.

https://en.wikipedia.org/wiki/Erich_Kretschmann

You are supporting a view that is proven false. To wit: formulating theories with equations having the same form in all co-ordinate systems is not a POR, neither does it have any physical meaning. So I suggest that you get your head out of your arse because you are only embarrassing yourself. — Preceding unsigned comment added by Kevin aylward (talk • contribs) 16:02, 12 June 2020 (UTC)

Sign all your talk page messages with four tildes (~~~~) and indent the messages as outlined in wp:THREAD and wp:INDENT — See Help:Using talk pages.

Formal personal attack warning on your talk page: [4]. - DVdm (talk) 16:43, 12 June 2020 (UTC)

Newton's law of universal gravitation

How is my reason to remove the content not relevant? Problematic statement, "Newton's theory of gravitation requires that the gravitational force be transmitted instantaneously. Given the classical assumptions of the nature of space and time before the development of general relativity, a significant propagation delay in gravity leads to unstable planetary and stellar orbits."

First problem: no reliable source to back up this claim that it is indeed a theoretical concern of Newton's law.

Second problem: how is instantaneous force a concern anymore with modern physics? Literally, all 4 known fundamental forces in physics happen instantly. Simply put, this concern here is outdated and no longer is a concern. 14.169.171.239 (talk) 18:50, 12 June 2020 (UTC)

But this is not in the context of moden physics. It says "Given the classical assumptions of the nature of space and time before the development of general relativity."

Anyway, I think it's best to take this to article talk page. Here we can discuss user related matters and other non-article related topics. - DVdm (talk) 20:36, 12 June 2020 (UTC)

.

The Institute for Statecraft is a GONGO

The Institute for Statecraft is a government-organized Non-governmental Organization just like the American GONGO National Endowment for Democracy.--88.66.151.168 (talk) 17:24, 16 June 2020 (UTC)

New Page Reviewer newsletter June 2020

Hello DVdm,

Your help can make a difference

NPP Sorting can be a great way to find pages needing new page patrolling that match your strengths and interests. Using ORES, it divides articles into topics such as Literature or Chemistry and on Geography. Take a look and see if you can find time to patrol a couple pages a day. With over 10,000 pages in the queue, the highest it's been since ACPERM, your help could really make a difference.

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In late February, Google added 5 new languages to Google Translate: Kinyarwanda, Odia (Oriya), Tatar, Turkmen and Uyghur. This expands our ability to find and evaluate sources in those languages.

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• A discussion on handling new article creation by paid editors is ongoing at the Village Pump.
• Also at the Village Pump is a discussion about limiting participation at Articles for Deletion discussion.
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Modern flat Earth societies‎

Yes. Also, those works are broadly geocentric, anyway. Thanks for the correct edit action. Regards, El_C 20:45, 21 June 2020 (UTC)

Draft Article

Hi, i have been created a page but it turned to draft and it has been declined. However there is a version of german. Also there are lots of sources. Can you check? Draft:Şanışer Baran Ahmet (talk) 07:16, 25 June 2020 (UTC)

I'm afraid I can't help there. Best to go to the deletion discussion. Good luck! - DVdm (talk) 09:17, 25 June 2020 (UTC)

Photoelectric effect edit

Hey. I noticed you reverted the metal/material edit Photoelectric effect. Photoemission is actually possible (I've done it myself), from any conductor, no matter how bad (metal, semimetal, semiconductor, superconductor), so replacing metal with material wasn't that bad. Even insulators will photoemit, but the electrons will be discouraged from leaving the surface of the material due to charging. Ponor (talk) 10:05, 3 July 2020 (UTC)

Hi Ponor, yes, with very high frequency light it's possible, but in metals it is much more common — see, for instance this source. My revert was mostly aimed at the edit symmary "Fixed possible typo", changing the correct "metal" into "meterial", not "material". A pretty sloppy edit that was... - DVdm (talk) 10:50, 3 July 2020 (UTC)

Oh I see. Never mind. I'll be working on this article (PE is my specialty) and I'll see what to do with it. We start with 'material', then limit ourselves to metals, and switch back and forth. Btw, a small gap semiconductor wouldn't need that much higher light freq. Photoemission from metals is more of a historical thing. Cheers! Ponor (talk) 11:28, 3 July 2020 (UTC)

Special relativity edits

I have noticed that you have sent this warning only for me but not for the other editor. I think that it is not fair. I will complain your behavior to senior advisory board. It seems to me that you conduct biased editing. I would like to note, that my edits are based on primary source - 1905 A. Einstein article. As soon as tomorrow I will start formal disputer resolution. Cheers! --185.71.245.255 (talk) 21:53, 5 July 2020 (UTC)

Since I am a novice here, could you please to inform me, what should I do so as to write a complain? I insist, that these words that relativity of simultaneity is experimentally proven concept be removed from the article --185.71.245.255 (talk) 21:56, 5 July 2020 (UTC)

If these words will be removed, I will refrain from complaints; otherwise I will be forced to release some smell and all my actions will be recorded in the Wikipedia edit history --185.71.245.255 (talk) 22:03, 5 July 2020 (UTC)

See wp:BRD. You need go to the article talk page and carefully explain what you have in mind, based on and backed by proper wp:reliable sources, which In this case probably means textbook sources. Next time you make this edit without establishing a solid wp:CONSENSUS for it, you'll be blocked. Also, making threats will get you nowhere. On the contrary, they will get you out of here before you can say WOW. - DVdm (talk) 22:07, 5 July 2020 (UTC)

This is the excerpt from reliable primary source: A. Einstein's 1905 paper - If at the point A of space there is a clock, an observer at A can determine the time values of events in the immediate proximity of A by finding the positions of the hands which are simultaneous with these events. If there is at the point B of space another clock in all respects resembling the one at A, it is possible for an observer at B to determine the time values of events in the immediate neighbourhood of B. But it is not possible without further assumption to compare, in respect of time, an event at A with an event at B. We have so far defined only an " A time " and a " B time." We have not defined a common " time " for A and B, for the latter cannot be defined at all unless we establish by definition that the " time " required by light to travel from A to B equals the " time" it requires to travel from B to A. 185.71.245.255 (talk) 22:08, 5 July 2020 (UTC)

It seems that you treat me

On the contrary, they will get you out of here before you can say WOW .Please note that you tone is far away from being polite. I think it directly violates some of Wikipedia policies. Could you please refrain speaking to me this way. I will complain your behavior to senior advisory board. Also, please revert your edits and remove words that relativity of simultaneity is experimentally proven concept.185.71.245.255 (talk) 22:13, 5 July 2020 (UTC)

Article talk page. But first familiarise yourself with wp:SYNTHESIS and wp:No original research. Otherwise you will be wasting your time on Wikipedia.

And I am not threatening you. I am warning you about what will happen if you make treats about "releasing some smell". Trust me, that is not a good idea. - DVdm (talk) 22:17, 5 July 2020 (UTC)

Thank you very much for you kind advise to go to the talk page. But, it seems to me it is better to start dispute resolution; I have clearly provided primary source and do not understand why do you violate WP:PRIMARY and WP:NPOV. On the contrary, they will get you out of here before you can say WOW. That apparently violates WP:PA. Please note that WP:CIV policy states: Be careful with user warning templates. Be careful about issuing templated messages to editors you're currently involved in a dispute with, and exercise caution when using templated messages for newcomers (see Wikipedia:Please do not bite the newcomers). Consider using a personal message instead of, or in addition to, the templated message.

Please also note, that another user started edit war; so your message should be sent to that user also. Hence, your behavior clearly violates WP:NPOV. Best personal regards, --185.71.245.255 (talk) 22:39, 5 July 2020 (UTC)

@185.71.245.255: It appears you do not have an understanding of how Wikipedia works and what special relativity is. Issuing threats and making bizarre statements will not get you anywhere. (talk) 22:59, 5 July 2020 (UTC)

Attention editors DVdm and Nerd271. Please note that the source that you have added neither primary, not reliable. Actually it doesn't matter, since the source clearly says that "no specially designed experiment have been carried out to test relativity of simultaneity". Hence it cannot be used as a source. Indeed, as soon as one way speed of light even in principle cannot be measured prior to certain clock synchronization scheme the concept of relative simultaneity cannot be experimentally confirmed . Please familiarize yourself with wp:SYNTHESIS and wp:No original research. Primary source WP:PRIMARYis the celebrated A. Einstein's 1905 article "On the electrodynamics of moving bodies" which clearly indicates that distant simultaneity is conventional. The article must be in accordance with WP:NPOV. Please familiarize yourself with the WP:PRIMARY A. Einstein's 1905 article "On the electrodynamics of moving bodies". Let's discuss it on the article's talk page some days later or should you agree with my note and WP:PRIMARY just delete that claim that Relativity of Simultaneity can be experimentally confirmed, this way we can avoid boring dispute resolutions. I trust that together we are on the right track to improve the article. Cheers! It should be noted that while the article is good. this claim is not supported by any reliable source and must be deleted 84.15.180.53 (talk) 20:59, 6 July 2020 (UTC)

I agree with user Nerd271 that it appears that you do not have an understanding of how Wikipedia works. Of course that is to be expected if indeed, as you say, you are "a novice here". You seem to have got it completely backwards. Wikipedia does not need wp:primary sources. Wikipedia needs wp:secondary sources. I added one that explicitly backs the content. And by the way, you cannot just remove properly sourced content, basing yourself on your wp:original research and wp:synthesis of some sources, specially not of primary ones. Wikipedia does not work that way. What you are facing now, is wp:NOCONSENSUS, and as you can verify, "In discussions of proposals to add, modify or remove material in articles, a lack of consensus commonly results in retaining the version of the article as it was prior to the proposal or bold edit." - DVdm (talk) 21:53, 6 July 2020 (UTC)

Edit of Imaginary unit

Hi DVdm.

My change is consistent with the current source. That's because the unchanged article misinterprets the source. The source does NOT say that that a and b must both be positive. I know this because I own a copy of the source and looked it up. The source uses an example from which it's clear that a and b cannot both be negative. This is very different to inferring that a and b must therefore both be positive, which is what the article currently does.

It's trivial to see that one of a and b can be negative: Sqrt[-4] = Sqrt[4 x -1] = Sqrt[4] x Sqrt[-1] = 2i is quite correct.

So my edit fixes two mistakes in the article: An incorrect mathematical statement and the incorrect use of a source. I suggest you refer to the source yourself and check this.

Kind regards.

Incredible. Dr Incredible (talk) 07:13, 6 July 2020 (UTC)

@Dr Incredible: ok, go ahead and feel free to refix, mentioning the source in your edit summary. Cheers. - DVdm (talk) 07:18, 6 July 2020 (UTC)

@DVdm: Actually I've re-considered my position. I still think the source is being misinterpreted, but the mathematical statement is correct: a and b must both be positive. Sqrt[-4] = Sqrt[4 x -1] = Sqrt[4] x Sqrt[-1] = 2i is not correct, it should equal pm 2i. Otherwise:

Sqrt[-4] = Sqrt[4/-1] = Sqrt[4]/Sqrt[-1] = 2/i = - 2i and Sqrt[-4] = Sqrt[-4/1] = Sqrt[-4]/Sqrt[1] = 2i which is inconsistent.

So I will not currently be making any changes, but will keep an eye open for a more explicit source.

Kind regards.

Incredible Dr Incredible (talk) 17:42, 6 July 2020 (UTC)

Please indent your talk page messages as outlined in wp:THREAD and wp:INDENT — See Help:Using talk pages. Thanks.

@Dr Incredible: hmm; hold it with that pm 2i there. Sqrt(4) = 2 and Sqrt(-1) is actualy meaningless, but if we write it nevertheless, then it equals i, (not -i, and not pm i). Sqrt is supposed to always give the principal value. See also the last sentence of Imaginary unit#Proper use. There is a reason why we don't write sqrt(-1). This has been discussed on the talk pages many times. The current version has been pretty stable for quite a while, and seems to have earned a long standing consensus now, so I propose to keep the article the way it is now. Let's keep it clear and safe. - DVdm (talk) 17:57, 6 July 2020 (UTC)

@DVdm: The only change I'd consider making would be a more appropriate source that explicitly states what is stated in the article.

Re: Sqrt(-1) = i. OK, you're making a distinction between Sqrt and sqrt. Of course one can always define Sqrt to mean the principle square root. Otherwise $-1=i^{2}$ gives us ${\sqrt {-1}}=\pm i$ and ${\sqrt {}}$ must be explicitly defined as giving the principle value before ${\sqrt {-1}}=i$ is correct. For real numbers we decide early on that ${\sqrt {4}}=2$, the positive root. Once we get to complex numbers, ${\sqrt {4}}=2$ is ambiguous, and we either have to live with that ambiguity or introduce such explicit definitions.

Anyway, I have no debate against your proposal except to say that a better (and non-circular) source (that gives a clear and explicit statement which is not open to interpretation) is needed IMHO. Such a source seems remarkably scarce.

Kind regards.

Incredible Dr Incredible (talk) 23:26, 6 July 2020 (UTC)

Yep, a better (or an additional) source will certainly do no harm . I'll also try to find one tomorrow. Cheers - DVdm (talk) 23:36, 6 July 2020 (UTC)

 Done @Dr Incredible: See [5]

References

Cast in concrete now - DVdm (talk) 09:53, 7 July 2020 (UTC)

Nice try, DVdm. But there's a snag: Those references are only dealing with real numbers (unless I've missed something), simplification of roots of negative numbers such as ${\sqrt {-27}}$ are not considered. What's needed is either a reference or a proof that says ${\sqrt {a\times b}}={\sqrt {a}}\times {\sqrt {b}}$ is valid for a,b > 0 or one of a,b < 0 but is not valid for both a,b < 0.

The rule ${\sqrt {\frac {a}{b}}}={\frac {\sqrt {a}}{\sqrt {b}}}$ should also be mentioned because the restrictions on its validity are different: Valid only for both a,b > 0.

(In both rules the restrictions are needed to avoid contradictions).

Furthemore, when a,b > 0 the case ${\sqrt {-{\frac {a}{b}}}}$ must be treated as ${\sqrt {-1\times {\frac {a}{b}}}}$ (for the aforementioned reason).

So this part of the article still needs some work.

I'd be happy to make the required changes, but I don't think any changes to the content can be made until a reference (or proof) that explicitly covers all of the above can be found. As I said earlier, references seem rather scarce.

Incredible. Dr Incredible (talk) 10:55, 9 July 2020 (UTC)

Let's not forget that the section Imaginary unit#Proper use is about avoiding making mistakes. Sure, perhaps the mistakes can be avoided by allowing still one of a,b < 0, but they can surely be avoided by demanding both a,b > 0. The latter is now explicitly supported by the sources. Clearly in both cases the calculation rules ${\sqrt {a}}\cdot {\sqrt {b}}={\sqrt {a\cdot b}}$ and ${\frac {\sqrt {a}}{\sqrt {b}}}={\sqrt {\frac {a}{b}}}$ are abused, and we can avoid the abuse by always demanding both a,b > 0 (and thus also only real). And of course, if we do not write ${\sqrt {-1}}$ to begin with, but rather i, we cannot make the mistake. If we never, ever write nonsense like ${\sqrt {-27}}$, we won't make mistakes. That's why we write $i{\sqrt {27}}$. I don't think that part of the article needs work, as it's there to give a warning and a clear, sourced recipe for how to avoid making mistakes. - DVdm (talk) 11:54, 9 July 2020 (UTC)

@Dr Incredible: FWIW, I have added another source, backing the entire section: [6]

References

The pages 30-34 should cast it in reinforced concrete - DVdm (talk) 15:33, 9 July 2020 (UTC)

Yes, I found that source too. I agree that its suggestion is the simplest. But it's more *ahem* complex than that: There are many secondary school textbooks (in Australia, for example) that explicitly set questions like "simplify ${\sqrt {-27}}$" etc. Even worse, these questions are set at the very start of the introduction to complex numbers, so the idea of the principle square root cannot even be meaningfully introduced (as an analogue to the conventional 'positive square root'). So the mistakes can't be avoided simply by saying to only use when a,b > 0. Otherwise you have Wikipedia butting heads with the secondary school textbooks of an entire country .... What's needed is a clear statement of exactly when those rules can be validly used. There's no doubt that something like ${\sqrt {-27}}=3{\sqrt {3}}i$ can make sense when things are properly defined or/and the rules are clear. The problem is that many secondary school textbooks are hopelessly wrong in how they explain this stuff (and so cannot be used as sources) and university level textbooks avoid the question altogether either by omission or by giving the advice to only use when a,b > 0 (and so are not useful sources).

The more I think about it, the more I think that the justification has to come via examples:

${\sqrt {27}}=3{\sqrt {3}}$ so (by the convention of using the 'positive square root') valid to use when a,b > 0,

${\sqrt {-27}}={\sqrt {-1\times 27}}=3{\sqrt {3}}i$ so valid to use (if ${\sqrt {}}$ is the analogue of the positive square root called the principle square root) when one of a,b > 0,

${\sqrt {-3\times -9}}$ leads to a contradiction so NOT valid to use (if ${\sqrt {}}$ is the analogue of the positive square root called the principle square root) when both a,b < 0.

Alternatively, the condition $-\pi <{\text{Arg}}(a)+{\text{Arg}}(b)\leq \pi$ on the principle arguments of a and b is discussed and used as a justification.

Anyway, these are my thoughts. It's only a small thing, but it looks like the Wikipedia article has the opportunity to make the definitive statement on this.

Incredible Dr Incredible (talk) 23:47, 9 July 2020 (UTC)

That reminds me of my old algebra teacher during my all-math prep year between highschool and university, the one who used to shred or rip our homeworks and tests to pieces when he couldn't discern a handwritten digit "6" from a letter "G", all in the name of care and precision. He also told us he'd do the same when he'd come across something negative (or even unspecified) under the radical sign. Even to this day, when typing ${\sqrt {-1}}$, I still feel an eerie urge to check behind me if he's there. I loved that teacher. He was one of the teachers who inspired me to decide to go for a math master's at university . DVdm (talk) 09:37, 10 July 2020 (UTC)

Cool teacher! Fair call, too. I hope he knew how you (and I'm sure many other students) felt. I bet you always calculated the discriminant first before using the quadratic formula. (But what did you do when using the cubic formula?) It's an uphill battle in Australia with many school textbooks forcing students to deal with negatives under the radical sign as part of an 'introduction' to complex numbers. There's an interesting discussion here: https://mathematicalcrap.com/2018/06/09/witch-2/#comment-3369 . And here: https://mathematicalcrap.com/2018/06/11/witch-3/#comment-3370

Incredible. Dr Incredible (talk) 10:47, 10 July 2020 (UTC)

An equation for the cycloid of the form y = f(x)

I don't have any reliable sources to cite but I've written my own demonstration of it on Desmos' graphing calculator (which can't be used as a source, of course):

${\begin{aligned}&f\left(x\right)=\sin \left(x\right)+x,\\&N=\infty \in \mathbb {N} ,E=2\pi ,\\&I\left(x\right)={\frac {E\sum _{n=1}^{N}\left\{x\geq f\left({\frac {En}{N}}\right):1,0\right\}}{N}}{\text{ (rough inverse)}},\\&f_{i}\left(x\right)=I\left(x\right)+{\frac {E\left(x-f\left(I\left(x\right)\right)\right)}{N\left(f\left(I\left(x\right)+{\frac {E}{N}}\right)-f\left(I\left(x\right)\right)\right)}}{\text{ (with linear interpolation)}},\\&f_{ip}\left(x\right)=f_{i}\left(\operatorname {mod} \left(x,E\right)\right)+E\operatorname {floor} \left({\frac {x}{E}}\right){\text{ (with repetition)}},\\&\cos \left(f_{ip}\left(x\pm \pi \right)\right)+1{\text{ (the cycloid)}}.\\\end{aligned}}$

Also, how would you integrate instead of summing? If integrated, linear interpolation wouldn't be necessary here.

I also found this: ${\frac {p(1-\cos(f^{(-1)}{\Bigl (}{\frac {2\pi x}{p}}{\Bigr )}))}{2\pi }}$given $f(x)=x-\sin(x)$ and $f^{(-1)}(x)$ is its real valued inverse.

I've tried looking up on the Internet about this but there's a lack of information, probably because of the keywords I use. I really need help with this. - AnastDunba (talk) 10:40, 12 July 2020 (UTC)

@AnastDunba: Another reason for absence of sources could be that the content is insufficiently noteworthy — see WP:NOTEWORTHY. Absence of reliable sources for some content usually implies that Wikipedia should not include it. Hope this helps a bit. Cheers. - DVdm (talk) 10:55, 12 July 2020 (UTC)

But what about $\sin \left(x\right)+x$ itself? All I've found is Kepler's equation; looking up “inverse of sin(x)+x” doesn't tell much, I come across a lot of flawed answers that doesn't help much. - AnastDunba (talk) 11:07, 12 July 2020 (UTC)

And what's this supposed to be? $f^{-1}(y)=\sum _{n=1}^{\infty }{\frac {y^{n/3}}{n!}}\lim _{\theta \to 0}\left({\frac {\mathrm {d} ^{\,n-1}}{\mathrm {d} \theta ^{\,n-1}}}\left({\frac {\theta }{\sqrt[{3}]{\theta -\sin(\theta )}}}\right)^{n}\right).$ Why the higher-order derivatives? I know that this is now unrelated to the cycloid but I'm getting confused by this. - AnastDunba (talk) 12:52, 12 July 2020 (UTC)

I guess it was just about the Kepler's equation the entire time regarding $\sin \left(x\right)+x$, sorry for bugging. -- AnastDunba (talk) 13:03, 12 July 2020 (UTC)

No problem. Happy source hunting . - DVdm (talk) 14:48, 12 July 2020 (UTC)

Notation for continued fractions

The notation I used is used on The Mathematical Functions Site from Wolfram Research (https://functions.wolfram.com). Here are examples of the usage: https://functions.wolfram.com/ElementaryFunctions/ArcTan/10/ https://functions.wolfram.com/ElementaryFunctions/Sqrt/10/ Does that count as a reliable source? A1E6 (talk) 18:58, 13 July 2020 (UTC)

Wolfram is not always reliable. A textbook source would be preferable. You can try Google books search. Happy hunting! - DVdm (talk) 19:06, 13 July 2020 (UTC)

@DVdm: But why not? A1E6 (talk) 19:48, 13 July 2020 (UTC)

I have seen it having mistakes and being removed as a source in the past. Can't name specifics at this moment. I suggest you ask at the respective article talk pages whether the other contributors would agree using it as a source - see wp:CONSENSUS. Feel free to point to this little discussion through [[User talk:DVdm#Notation for continued fractions]]. Good luck! - DVdm (talk) 21:07, 13 July 2020 (UTC)

@DVdm: I've checked over 50 books on the topic for the notation from Wolfram, and actually no book uses it. That was quite surprising for me. I will revert my edits. A1E6 (talk) 19:40, 14 July 2020 (UTC)

@A1E6: yes, in that case the notation is de-facto likely insufficienly wp:noteworthy. If indeed it were, other editors would redo or go to the article talk page. Thanks & cheers. - DVdm (talk) 08:33, 15 July 2020 (UTC)

Bad source

@DVdm: You remove my changes from https://en.wikipedia.org/w/index.php?title=Imaginary_unit&diff=968931647&oldid=968914796 - but I take this source from other wikipedia article https://en.wikipedia.org/wiki/E_(mathematical_constant)#cite_note-OConnor-5 (!!!) - can you explain what is wrong with it and fix that article which also use that source? — Preceding unsigned comment added by Kamil Kielczewski (talk • contribs) 11:33, 22 July 2020 (UTC)

Please sign all your talk page messages with four tildes (~~~~) — See Help:Using talk pages. Thanks.

I replied on your talk page: User talk:Kamil Kielczewski#Source. - DVdm (talk) 12:11, 22 July 2020 (UTC)

My changes

Dear friend, I cannot provide a source because this logic was suggested by my father. It is mathamatically sound, but you should go over it if you wish. Also, I noticed that one of the paragraphs didn't have a proper conclusion, so I added one. Please go over it once more. Thanks Rak Laptudirm (talk) 12:59, 2 August 2020 (UTC)

Hi Rak Laptudirm, unfortunately, this does not count for Wikipedia. wp:Reliable sources are required (1) to provide a way to verify new content, and (2) to establish whether new content is noteworthy to be included. - DVdm (talk) 13:11, 2 August 2020 (UTC)

Ok, sure. Thank you for the information. Rak Laptudirm (talk) 14:40, 2 August 2020 (UTC)

My apology

I apologise for editing the Wikipedia page for "Caracal" without using a reliable source. I thought my source was reliable at the time, but I know realise that it was not. I will try to be more vigilant in the future. Roman Biggus (talk) 13:20, 17 August 2020 (UTC)

Sorry, I was trying to put them under my name

If you want the real Relativities that Garret and Stephen referred to, you need to publish my 41 years of thought experiment.

You know, the Justification for the Metric System ?

It's your loss if you don't, Ask Garret Lisi for confirmation. They are all under my IP address, I've created a username bernhard.eringa, put them all under that name if you like, the titles are true english descriptions though, up to my peers to figure out the precedences.

Sorry again.

Regards Bernhard Eringa 13 Quantum Theory PhD's hanging on the walls of the N.Z. Governments Prime Minister's Office since 1983. — Preceding unsigned comment added by 121.99.160.104 (talk) 20:30, 29 August 2020 (UTC)

Please sign all your talk page messages with four tildes (~~~~) — See Help:Using talk pages. Thanks.

There is probably no place for this in Wikipedia. See our policy on wp:original research. You will have to seek another venue. Good luck. - DVdm (talk) 21:15, 29 August 2020 (UTC)

Note to self, see Bernhard.Eringa (talk · contribs · deleted contribs · logs · filter log · block user · block log). - DVdm (talk) 21:50, 29 August 2020 (UTC)

Full revert of an edit (derivation of a physics formula) in Elastic collision article due to lack of citation

Hi DVdm,

Re: Full revert of an edit (derivation of a physics formula) in Elastic collision article due to lack of citation (copied from my user talk page)

Thank you for the notice of lack of citation. The derivation is elementary, so it does not require a source & its validity can be verified easily. Nevertheless, citation has been added.

However, my edit should have remained but been tagged for citation. It is not appreciable that the edit was reverted in its entirety, which is disproportionate and is demotivating in participating further in Wikipedia. But, I really do appreciate that you reached out directly on my talk page, which I wish established editors would engage in more.

FYI, I may be adding to that article further re: Body assumptions; Programming; Ideal & non-ideal classical mechanics; Statistical mechanics. Will keep in mind citations and will appreciate discussion before full reverts.

Thank you,

173.206.33.141 (talk) 19:17, 2 September 2020 (UTC)