Lordofdominion

July 2018

Hello, I'm DVdm. I noticed that you made a change to an article, Integration by parts, but you didn't provide a source. I’ve removed it for now, but if you’d like to include a citation to a reliable source and re-add it, please do so! If you think I made a mistake, or if you have any questions, you can leave me a message on my talk page. Thanks. DVdm (talk) 08:32, 26 July 2018 (UTC)

/* Recursive integration by parts */ Discussion on methods used to implicitly solve for integrals using tabular integration by parts.

Hi Dvdm,

I made two edits on Integration by Parts.

The first, where I rewrote C' as $C=C/2$, is because in calculus the convention is to treat C as an arbitrary constant when evaluating indefinite integrals. Because the derivative (inverse) of an integral leads any constants to go to zero, for the purposes of calculus, $C'=C/2=C$ are all equivalent statements.

The second edit is as follows:

"In this instance, an explicit expression of $\int e^{x}\cos x\,dx$ was found by algebraically deriving the same expression using tabular integration, and then solving for it in terms of $x$."

^ This is a summary of the steps that were taken above.

"This implicit derivation allows us to solve integrals where transcendental functions may be involved, or where the derivatives do not go to zero, as with polynomial functions."

^ Transcendental functions, per their wiki page, include the logarithm, the exponential function, and the trigonometric functions. In the example preceding, all functions involved were transcendentals. The statement above is backed by the algebra broken down in the steps preceding.

"Multiple integrals may be constructed for more complex expressions, and if necessary each integral can be evaluated using this method."

^ This could have been worded differently. My meaning was that, because by it's very nature integration by parts creates a second integral, this second integral can be evaluated by the same method (tabular or standard) as above. This is simply a recursive use of integration by parts, and is internally consistent.

I do not have a source to cite in this instance. I back up my statements with my BS in Mathematics, and my own personal work tackling this topic. I saw an opportunity to improve the wiki page, and I hope my edits (slightly changed, in the case of the third sentence) make it through.

Thank you, LoD

01:23, 27 July 2018 (UTC)

Hi there, perhaps you don't know that $C=C/2$ is equivalent to $C=0$. That was one part of the reason why I undid your edit. Now you could start a discussion about that, but I'm not going into that. This (—avoiding discussions that are bound to go nowhere—) is probably the main reason why Wikipedia requires wp:reliable sources for everything, specially when challenged—see wp:BURDEN. Hope this helps! Cheers. - DVdm (talk) 10:00, 27 July 2018 (UTC)

In response to your points raised: The [constant of integration], as discussed on the (sourced) Wiki page here, explicitly says: "any value for C makes {\displaystyle F(x)+C} F(x)+C a valid antiderivative". This is what I argue above, and the basis of my first edit. This is standard calculus.

The second paragraph, I maintain, is a summary of the previous discussion, and no citation is needed.

The third paragraph is substantiated upon closer inspection of the preceding discussion, and at the end of this PDF provided by the mathematics department at Virginia Tech, a discussion on integration by parts.

The fourth paragraph is justified by the third, because it follows that if an expression is obtained that cannot be easily evaluated, then the same technique as in paragraph 3 can be used to solve it.

I do not know what constitutes valid sources for a mathematics wiki page, and I do not know what is really necessary here, but I assure you all of my assertions stand to scrutiny. My edits rely on the extremely common convention of generalizing procedures and results to more complex procedures, and recursive use of techniques in more complicated expressions is commonplace. Please advise. If you do not have the necessary mathematical background, if possible, please consult with another Wiki mod that does. I look forward to hearing from you.Lordofdominion (talk) 12:47, 27 July 2018 (UTC)

Regarding the second paragraph being a "summary of the previous discussion, and no citation is needed", see the policy about wp:No original research: "To demonstrate that you are not adding OR, you must be able to cite reliable, published sources that are directly related to the topic of the article, and directly support the material being presented." So yes, a citation is needed. The unpublished piece of pdf you have there does not qualify as a reliable source for Wikipedia. From your first edit it is clear that indeed you don't have the "necessary mathematical background", so my advise is to stay away from mathematics related articles. Cheers. - DVdm (talk) 13:16, 27 July 2018 (UTC)

What is your response to my citation of Wikipedia's discussion on the arbitrary nature of the constant $C$?Lordofdominion (talk) 13:22, 27 July 2018 (UTC)

Sorry, I am not going to invest time in explaining what was wrong with your first edit. You can ask at our wp:Reference desk/Mathematics. Good luck! - DVdm (talk) 13:32, 27 July 2018 (UTC)

I'm disappointed that you're not willing to address my feedback in full. Your removal of my edits is based on my failure to cite sources, which I can respect. Your failure to investigate my justification for my edits is noted, but unwarranted in this case. Without a mathematical background, you should not be moderating these pages, if you're unable to assess the validity of any edits made. $C=0$ is valid, and $C=1,C=2,C=3,C=4,...$ are valid... It doesn't matter what it is. It's arbitrary. Have a good day.Lordofdominion (talk) 13:37, 27 July 2018 (UTC)

$C=0$ is not arbitrary. It is zero. Wikipedia does not give a hoot about our backgrounds, but trust me, I do have a —solid— mathematical background. Have a nice day at the reference desk. They really tend to be more patient . - DVdm (talk) 13:44, 27 July 2018 (UTC)

• Saying that C is arbitrary means that whatever value C has, another value could have been taken, so that you may write C to mean the same number I write as C/2, without either of us being wrong: we are independently and separately using two different notations. However, it is not permissible to use the two notations together in the same context: you cannot write C = C/2 and intend the two uses of "C" to refer to different numbers.
• It is not at all clear what "This implicit derivation allows us to solve integrals where transcendental functions may be involved, or where the derivatives do not go to zero, as with polynomial functions" is intended to mean.
• Citing "my own personal work tackling this topic" as justification for editing is not acceptable. original research is not published by Wiki8pedia, and just anyone who comes along to Wikipedia and says that they have worked something out for themselves is not a reliable source. The editor who uses the pseudonym "JamesBWatson" (talk) 14:32, 27 July 2018 (UTC)

Thank you for going through this! I'll be able to respond in more detail tonight. I am confused on this, though: I understand original research is not acceptable for Wikipedia, but if a concept or claim can be mathematically proved in an article, is that acceptable? If it's bad math then it's bunk, of course, but is there any leeway for claims that can be demonstrated? It seems like when it comes to demonstrable math, original research is... a bit inevitable sometimes.Lordofdominion (talk) 15:02, 27 July 2018 (UTC)

Regarding your question "if a concept or claim can be mathematically proved in an article, is that acceptable?": no, really not. Wikipedia is not a publisher of wp:original research. There are exceptions for simple arithmetic —see wp:CALC— so your edit does not qualify. Even if everybody can verify the proof, the new content should appear in the literature to demonstrate its dueness for Wikipedia — see wp:DUE. There's a lot to learn about how Wikipedia works, I know... Please take some time to read the policies and guides that are linked in the above responses. - DVdm (talk) 16:34, 27 July 2018 (UTC)

OK. I do have several calculus textbooks on hand, and one or more may discuss what I discussed above, but then that raises the question in my mind of how that can be verified externally if someone (such as yourselves) do not have the same text to check for accuracy? Is that typically done? If this is addressed in the above links somewhere I apologize. I'll take a deeper look tonight after work. Thank you for breaking this down for me.Lordofdominion (talk) 17:02, 27 July 2018 (UTC)

Well, you might bring this to the article talk page Talk:Integration by parts, which is watched by the other regular editors of that article. Just say what you like to add to the article, cite the author, title, ISBN and page. Someone might have the book on their shelf, or maybe Google Books has part of it online. But... please don't do this $C=C/2$ thing... - DVdm (talk) 17:12, 27 July 2018 (UTC)

That's a minor quibble I'm happy to leave alone. :) I'll do some more research and drop a line over there then when I can. Thank you!Lordofdominion (talk) 17:24, 27 July 2018 (UTC)