Talk:Middle dot

General

1) The "middle dot" is also called a "center dot." I'm going to take a look in a minute and maybe add a redirect.

2) In British publications over some time period, the decimal point was represented with a center dot rather than a period. I'd add this to the main article except for two problems: I don't know what that time period was, and I don't have any good reference or authority for this fact other than my own observations. Dpbsmith 22:11, 4 Jan 2004 (UTC)

OK, I'm going ahead and adding it. I'm saying it was common "in the 1950s" because I know for sure that's true, maybe someone else can refine the date range later.

Here are two examples of the usage:

• Pearson, E. S. and H. O. Hartley, Biometrika Tables for Statisticians: Volume I, Cambridge University Press, Third Edition (1966) reprinted with additions. (Original publication was 1954).

• Cundy, H. Martyn and A. P. Rollett (1954), Mathematical Models, Oxford: at the Clarendon Press.

The latter is particularly interesting because sections and illustrations numbered with ordinary periods, which are also used in the nomenclature for identifying polyhedra. For example, p. 96 is headed

3.7.2. Cuboctahedron. 3.4²

Later on the same page, it says

${\frac {Edge}{Cube\ edge}}={\frac {1}{\sqrt {2}}}=0\cdot 707.$

So this text uses center dots as decimal points in numeric decimal fractions, but ordinary base-aligned periods in section designations.

In Australia (and I suspect many other places as well) it was the more-or-less universal standard way to write things. I'm not sure when it started, but it was certainly in force when I first met the decimal point back around 1965 or so, and it remained normal usage right up until the rise of computers made it uncommon to hand-write things. The demise of the decimal point in favour of the ordinary full-stop can be confidently sheeted home to the limitations of your average word processor. Using a full stop for a decimal point was like using a minus sign for an em dash: just one of those things you did as a kludge when your typewriter didn't have the right symbol on it.

I daresay that others of my generation share the memory I have of being initially confused by the visual weirdness of equations with asterisks instead of multiplication signs and full stops instead of decimal points. Vaguely, I recall having it explained to me. That would have been the early 1970s, I guess. Tannin 22:50, 4 Jan 2004 (UTC)

Which reminds me--in the 1960s, what about ordinary typewriters? Were Australian typewriters equipped with center dots on them for typing decimals? If not, how did people type them? Dpbsmith 23:28, 4 Jan 2004 (UTC)

You rolled the paper up a little bit, hit the full stop key, and rolled it back down again; otherwise you could leave a spaceand add the dot by hand; or else you just used a full stop and put up with it looking funny. At least that's how I remember it. I'll ask someone older, if I remember to, such as my father. I was pretty young at the time. Tannin

Tannin is right, except that you actually rolled the paper down, of course, to effectively raise the full stop and turn it into a decimal point - by one click of the typewriter barrel (= half spacing). Same thing for degrees (raised lower-case o), powers, etc. Oh, what fun it all was apostrophe-backspace-full stop -- Picapica 15:25, 7 Aug 2004 (UTC)

Does anyone know if the middle dot is still cited as the correct decimal point in now-out-of-print Hart's Rules, which a lot of publications still use as a house style? Stombs 00:47, Jan 2, 2005 (UTC)

Continuity/flow

Llull, I have combined the two Chinese paragraphs again, because they are both on that same theme, that being, well, both Chinese. I read your summary carefully ("I put the Catalan part up because of is a language ortography caracteristic"), but do not find that it is a suitable justification for inserting a Catalan paragraph between two Chinese on a very related topic: "partition mark". If the reason you moved the Catalan paragraph up is something else, like because you felt that having it one paragraph lower is disrespecting Catalonia or something like that (not to put words in your mouth), then move it to the first paragraph (after the intro). I do not care, but it is better for the reader not to disrupt the continuity of themes in the article. --Menchi (Talk)â 23:25, 4 Jan 2004 (UTC)

Raised point as "times sign"

The raised point appears to be used consistently as the multiplication sign in Germany: 3·4=12. This seems not to be a purely coninental European thing, though, since France uses "x": 3x4=12. I wonder what the geographical ditribution of · versus x is. -- Picapica 15:55, 7 Aug 2004 (UTC)

Mathematicians frequently use a "multiplication dot", when they show a sign for multiplication at all (juxtaposition also means multiplication). When dealing with vectors, however, both the dot (⋅) and the cross (×) are used, and actually mean different kinds of multiplication. — Gwalla | Talk 01:26, 8 Aug 2004 (UTC)

Thanks for that clarification, Gwalla. What I was wondering about, though, was not "high-level" mathematics, but the ordinary, everyday notation of arithmetic as taught in primary schools; the kind of number multiplication where 3x4 (in German primary schools, 3·4) means 4+4+4. Here are some examples of teaching materials from Germany and Austria using the "multiplication dot" in elementary arithmetic: [1] - [2] - [3] - [4]. I'm not so sure as I was, though, about my earlier use of the word "consistently"; here's a counter-example: [5]. -- Picapica 08:07, 8 Aug 2004 (UTC)

In the United States, the × symbol is almost always used for multiplication in elementary school, while some time between middle school and high school the · or no punctuation at all is more often used to indicate multiplication. With vector calculus (usually around college level), the · is used for inner product, while the × is used for cross product.--69.212.99.174 19:34, 6 Nov 2004 (UTC) .

Middle dot as a diacritic

The page Diacritic links to here, as the Catalan usage, for example, can be considered diacritic. I'm gonna revert the Category:Diacritics removal for now; feel free to discuss it on Talk:Diacritic or Category talk:Diacritics and reach consensus either way. Tbh, I'm somewhat ambivalent; I merely populated the category with all the appropriate links from Diacritic. — OwenBlacker 11:34, Aug 17, 2004 (UTC)

There are two

There is the · · for language and the ⋅ ⋅ for math? Should be expanded.