The following discussion is an archived debate of the proposed deletion of the article below. Please do not modify it. Subsequent comments should be made on the appropriate discussion page (such as the article's talk page or in a deletion review). No further edits should be made to this page.

The result was no consensus. There's a pretty clear consensus to not delete this outright. Between some flavor of merge, redirect, and keep, no so much. -- RoySmith (talk) 05:06, 17 January 2016 (UTC)[reply]

Cis (mathematics)[edit]

Cis (mathematics) (edit | talk | history | protect | delete | links | watch | logs | views) – (View log · Stats)

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Unnecessary fork of Euler's formula and the exponential formula, as just another way of writing the latter, with the mathematical content already covered by the former. It may have once been common, but many mathematical formulae and notations were once commonly written another way, and do not have or need a separate article for that notation. JohnBlackburne^words_deeds 15:50, 9 January 2016 (UTC)[reply]

• Redirect to Euler's formula and move the history sentence in the lead to that article. Dmcq (talk) 15:58, 9 January 2016 (UTC)[reply]

• Keep The sources more commonly mention De Moivre's theorem in this context and this preceded Euler historically. As there are multiple contexts for the topic and the notation forms a reasonable topic by itself, it's fine as it is. In any case, no reason to delete anything has been put forward and so the nomination is fundamentally flawed. Andrew D. (talk) 17:58, 9 January 2016 (UTC)[reply]

• Keep Concur with above. Nomination has not been adequately substantiated and appears to be based on ideological preference. Bonehed (talk) 18:48, 9 January 2016 (UTC)[reply]

• • ideological? Which ideology do you think I am pushing with this nomination? As for “fundamentally flawed” I would also appreciate an explanation. The reason for deletion is the material is adequately covered elsewhere, making this an unnecessary content fork.--JohnBlackburne^words_deeds 19:04, 9 January 2016 (UTC)[reply]

• As explained at WP:REDUNDANTFORK, the inverse operation for a fork is merger, not deletion. But that's moot because there are multiple contexts for this topic and so it is not redundant. Andrew D. (talk) 19:11, 9 January 2016 (UTC)[reply]

• Redirect and merge are both appropriate outcomes for a deletion discussion, especially as a redirect existed before. I do not follow the second part of your reply, or at least do not see the multiple contexts. If there were, if it were widely used, you might expect many links to it (as the redirect existed before) but there was only one from an article.--JohnBlackburne^words_deeds 19:59, 9 January 2016 (UTC)[reply]

Have a look at the article. There's no real content there which the exponential function article doesn't deal with just as well or better if you discount the History and Pedagogical use sections which were put into another article in 2006 and never got any references. Those were deleted in 2008 with 'I completely removed cis. This is the consensus I see in the discussion page from over a year ago'. Wikipedia is not deletionpedia, a reference should at least have been found before reinstating that. Dmcq (talk) 16:37, 12 January 2016 (UTC)[reply]

• Retain somehow. If the nominator's right, redirect with the potential of a merger is the right course; if he's wrong, there's no reason to delete it. Nyttend (talk) 19:40, 9 January 2016 (UTC)[reply]
• I'm inclined to keep this. There are contexts in which the exponential notation is better avoided. One of those is when one wishes to prove that the function

${\displaystyle x\mapsto \cos x+i\sin x,\,}$

although defined in a way that is not explicit about its exponential nature, actually behaves like an exponential function. If the notation presupposes the thing to be proved, then it's either circular or confusing, depending on how the reader understands it. Michael Hardy (talk) 17:17, 15 January 2016 (UTC)[reply]

• Keep. While cis is not in main-stream use, it is a long established and notable function/notation used in various areas of mathematics, engineering and computer sciences. Perhaps it is most prominently used in conjunction with De Moivre's formula and Euler's formula, but not exclusively. So far, we were barely mentioning it in other articles without providing any details on cis for those who are interested in the history and uses of the function, and we couldn't add this information as it would be off-topic in articles such as Euler's formula. Therefore, I think, we need a "central" article on cis to discuss it in its own right and provide bridges to the various related topics. Several sources have been added to the article in the past week, and I'm sure more will come over the course of time (I plan to add a bunch of references myself as time allows). --Matthiaspaul (talk) 23:08, 15 January 2016 (UTC)[reply]

• Redirect to Euler's formula, or just delete. This is a bit ridiculous - it's just an obscure, antiquated notation for ${\displaystyle e^{ix))$ and the article completely lacks encyclopedic content. We don't need a separate article on every weird variation in mathematical notation. --Sammy1339 (talk) 18:21, 16 January 2016 (UTC)[reply]

There's nothing obscure or antiquated in that notation. The name has been established some 120 years ago and it is still actively used today in mathematics, engineering and information technology. It's clearly a notable topic in an encyclopedia. The article meanwhile also has references indicating its usage in math education, in several old as well as recent books and in various high-profile software products. There's quite a bit of encyclopedic content in the article already - history, usage examples, mathematical identities and properties - this wouldn't belong into a sidenote on cis in other articles, but it definitely belongs into an article on cis - that's why we need it. Besides, in my experience cis is more commonly used as a shorthand for cos(x) + i sin(x) than as an alternative notation for e^(ix). --Matthiaspaul (talk) 00:54, 17 January 2016 (UTC)[reply]

Most of the article is just about properties of the complex exponential function, with which it is synonymous. There's not enough coverage about the term for WP:WORDISSUBJECT. As for the pedagogical use, this applies to one proof - deriving Euler's formula using the angle addition formulas - and this can easily be done using other notations. I have no objection to mentioning in Euler's formula that this notation exists, but it's not suitable as the subject of an article. --Sammy1339 (talk) 01:49, 17 January 2016 (UTC)[reply]

Also, you are not making sense when you write "in my experience cis is more commonly used as a shorthand for cos(x) + i sin(x) than as an alternative notation for e^(ix)." Those expressions are equal. --Sammy1339 (talk) 01:51, 17 January 2016 (UTC)[reply]

The above discussion is preserved as an archive of the debate. Please do not modify it. Subsequent comments should be made on the appropriate discussion page (such as the article's talk page or in a deletion review). No further edits should be made to this page.