Talk:Witch of Agnesi

Witch of Agnesi has been listed as one of the Mathematics good articles under the good article criteria. If you can improve it further, please do so. If it no longer meets these criteria, you can reassess it.
Review: July 5, 2018. (Reviewed version).

A fact from Witch of Agnesi appeared on Wikipedia's Main Page in the Did you know column on 25 July 2018 (check views). The text of the entry was as follows:

Did you know... that the witch of Agnesi comes from a circle and kisses it?

A record of the entry may be seen at Wikipedia:Recent additions/2018/July. The nomination discussion and review may be seen at Template:Did you know nominations/Witch of Agnesi.

Wikipedia

Special nature

What's so special about this curve?--Anakata 18:28, 25 June 2006 (UTC)[reply]

The Witch of Agnesi is functionally equivalent to the Cauchy-Lorentz Distribution, which has many uses in mathematics and physics. The one with which I am most familiar is the Lorentzian profile, or "natural broadening", of atomic emission and absorption spectral lines. I have added a link to the Cauchy Distribution page under "See Also". AmberRobot 21:04, 21 February 2007 (UTC)[reply]

I would say that the special nature is due to the geometric definition which was added a few days after Anakata's question. Note that the curve is not unilaterally scaleable: stretching it in (only) the horizontal or vertical direction will change the curve into a non-witch (unlike, say, an ellipse, which can be scaled arbitrarily). So only specific Cauchy-Lorentz distributions are actually witches. Cheers, Doctormatt 00:31, 22 February 2007 (UTC)[reply]

Fermat

This page states that Fermat studied this curve in 1666, but Fermat's page states that he died in 1665. This combination seems improbable, as zombies generally prefer to eat brains rather than do mathematical research. Is there a source for this claim? Sean Patrick Santos (talk) 03:18, 27 August 2009 (UTC)[reply]

The date should be 1630, Fermat was in his late 20's. The article has been fixed.--RDBury (talk) 05:39, 7 September 2009 (UTC)[reply]

I took out the date because I couldn't find a proper reference to it and the references I did find simply say "before 1666" (duh). —David Eppstein (talk) 05:30, 18 May 2018 (UTC)[reply]

Error regarding centroid

As this curve is infinite in width and asymptotic with the x-axis (according to the illustration), the centroid of the curve should be (0,0). The centroid of the area between the curve and its asymptote is (0,a/2). Additionally, the centroid of the generating circle is the center of the circle at (0,a).

Versicra

A yet another example of internet proparating the nonsence, a modern mondegreen so to say. Even Britannica Online (as of today) writes that 'versicra' means 'witch' in Italian, which is nonsense, as easily verifiable from modern and old dictionaries. There was/is no such word.

In fact I suspect this is a modern artifact of OCR publishing. If you search google books for 'versicra' you will find some, but if you look into original images of the corresponding books, you will see it is 'versiera', and 'versicra' is just sloppy job of subsequent readers. Max Longint (talk) 17:54, 7 October 2011 (UTC)[reply]

interesting links:

Max Longint (talk) 18:29, 7 October 2011 (UTC)[reply]

Where and in which version of the article do you see "Versicra"? I've searched back to May of last year and cannot find it.--RDBury (talk) 06:00, 8 October 2011 (UTC)[reply]

I was writing about "intertet propagating nonsense". I am glad that wikipedia was not fooled with the magic word "Britannica".

Sorry I didn't make it clear that this post was a warning not to add "versicra" to the article, despite references floating around. Max Longint (talk) 19:01, 9 October 2011 (UTC)[reply]

Thanks for the clarification. We have a non-OCR version of the 1911 Britannica article on the subject at WikiSource. It doesn't mention "versiera" but it does state that Agnesi invented the curve when she only wrote about it. There are a number of such factoids that have been propagated as historical truth; the internet is not a requirement though it does speed up the process a bit.--RDBury (talk) 04:37, 10 October 2011 (UTC)[reply]

Centroid

I am questioning this article's value of the centroid's x-coordinate at Wikipedia:Reference desk/Mathematics#Does the Witch of Agnesi really have a well-defined centroid?. Comments are invited.--Jasper Deng (talk) 04:48, 8 September 2014 (UTC)[reply]

I took this out for now. If there is a centroid its x-coordinate must be 0 (by symmetry) and its y-coordinate is necessarily 0 (because of the heavy tails) but there are competing claims in the literature whether that really is the centroid or whether the centroid is undefined (because the integral that would define it diverges). The trouble is that "the integral that would define it" can mean any of several different things. Really, it's more a statement about the Cauchy distribution and its (lack of an) expected value, than about this curve itself, so I think it's ok to omit it. But we can put it back in if we find a source that goes into this issue in more depth than just the obvious considerations above, and handles it as a property of this curve rather than of the associated probability distribution. —David Eppstein (talk) 01:37, 18 May 2018 (UTC)[reply]

Capital "W"?

In mathematics, the Witch of Agnesi is ...

In mathematics, the witch of Agnesi is ...

This article currently consistently uses a capital "W". Should it? Michael Hardy (talk) 18:33, 1 June 2018 (UTC)[reply]

GA Review

This review is transcluded from Talk:Witch of Agnesi/GA1. The edit link for this section can be used to add comments to the review.

Reviewer: Power~enwiki (talk · contribs) 23:16, 3 July 2018 (UTC)[reply]

I'll do a first pass today, and will respond on Thursday to comments, but otherwise am unavailable until next Monday. That shouldn't be too much of a delay.

Rate	Attribute	Review Comment
1. Well-written:
	1a. the prose is clear, concise, and understandable to an appropriately broad audience; spelling and grammar are correct.	Phrasings like Let the curve be constructed as above feel more like a math research paper than an encyclopedia article.
	1b. it complies with the Manual of Style guidelines for lead sections, layout, words to watch, fiction, and list incorporation.	The "Properties" section possibly could be written in prose instead of in list form, but it's not an egregious issue.
2. Verifiable with no original research:
	2a. it contains a list of all references (sources of information), presented in accordance with the layout style guideline.
	2b. reliable sources are cited inline. All content that could reasonably be challenged, except for plot summaries and that which summarizes cited content elsewhere in the article, must be cited no later than the end of the paragraph (or line if the content is not in prose).	Citation #20 (citing a problem from the OED) doesn't seem like the other references; does the article need to separate footnotes from references? There's probably a simpler way to deal with it.
	2c. it contains no original research.
	2d. it contains no copyright violations or plagiarism.
3. Broad in its coverage:
	3a. it addresses the main aspects of the topic.
	3b. it stays focused on the topic without going into unnecessary detail (see summary style).	There is an example of the infamous "In popular culture" section here; but it serves as disambiguation for other things of this title that aren't otherwise notable, so I think that's fine.
	4. Neutral: it represents viewpoints fairly and without editorial bias, giving due weight to each.
	5. Stable: it does not change significantly from day to day because of an ongoing edit war or content dispute.
6. Illustrated, if possible, by media such as images, video, or audio:
	6a. media are tagged with their copyright statuses, and valid non-free use rationales are provided for non-free content.
	6b. media are relevant to the topic, and have suitable captions.	For the image captioned The Witch of Agnesi with labeled points, it may be pointing out that the path MP is the Witch in the caption (it's already mentioned in the prose "Construction" section). Regarding the image captioned The cross-section of a single water wave has a shape similar to the Witch of Agnesi. - is this simply by visual comparison, or is there a mathematical reason for the similarity described in reliable sources.
	7. Overall assessment.

Thanks for the review. I have made the following changes in response:

Copyedited the start of the Equations section to be less technical.
Removed the bullets in the Properties section.
Formatted the OED reference like the other ones (i.e. using {{citation}} to generate Citation Style 2).
Added the identity of the curve to the caption of the figure.
Removed the water wave figure as it didn't correspond to anything in the text and I couldn't find a source for waves having this shape.

—David Eppstein (talk) 02:19, 4 July 2018 (UTC)[reply]

Everything looks good at a quick glance, though I don't have time to do a full copy-edit pass today. power~enwiki (π, ν) 19:24, 4 July 2018 (UTC)[reply]

I've read through the entire article again and everything is good. Passing. power~enwiki (π, ν) 19:25, 5 July 2018 (UTC)[reply]