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According to the article, "[Concatenation] is more commonly written as "a"&"b"="ab", using the ampersand." Yet Concatenation and Comparison of programming languages (strings) both say + is more common. I'm removing the sentence. --192.235.8.2 20:52, 31 January 2007 (UTC)[reply]

• To join the fun with ¹ ² ³ ⁿ / ⅛ ¼ ⅜ ½ ⅝ ¾ ⅞ / ⅓ ⅔ ?
• Y/N?
• If yes, what are the code points?
• If no, someone should create them.
• Thanks, — M20-2.5 19:04, 17 March 2008 (UTC)[reply]

Yes x207a⁺ x207b⁻ x208a₊ x208b₋ See Unicode subscripts and superscripts. Why anyone wants them I don't know when one can superscript or subscript anyway. Dmcq (talk) 12:16, 22 January 2009 (UTC)[reply]

A personal tripod page is not a very good source. Maybe this book is better, even though it looks like it may have gotten the info from that same page. What about other sources? Anybody have? Dicklyon (talk) 17:31, 7 December 2008 (UTC)[reply]

I think there are three use for minus rather than 2.

x−y meaning the result of y subtracted from x −x meaning the result of negating the value of x, i.e. x subtracted from 0. -123 the negative number 123. It has the same value as the negation operator applied to 123 but is a different concept. I'll stick this in if nobody has a better idea.

Also a computery side might be an idea too. APL has negative numbers e.g. ⁻123 separate from negated integers and IEEE has -0. Dmcq (talk) 18:43, 21 January 2009 (UTC)[reply]

If you have a source that discusses these distinctions, then definitely add such. If not, don't. Dicklyon (talk) 18:53, 21 January 2009 (UTC)[reply]

Well the definitions in wikt:minus sign and wikt:plus sign clearly differentiate between the operation and as used as part of a number, also if you look at the article itself immediately after it says there are two uses it gives three different names for the three different uses I gave above though there is a citation mark on that sentence. Dmcq (talk) 22:42, 21 January 2009 (UTC)[reply]

• The difference between the second and third meanings is not at all obvious. As a unary operator, -5 is the negative (or "opposite") of 5, and, in exactly the same way, -x is the negative (or "opposite") of x. If there really is a "technical difference" as the article claims then I think the article should explain what that is. 86.134.90.10 (talk) 02:23, 18 March 2009 (UTC).[reply]

There is a difference, it would be hard for APL to distinguish between them for instance if there wasn't one. The citation referenced on the first line of the section might explain it better for you. Sorry I thought I had explained it properly but obviously there's some problem. As it say in the second type it is part of the number, no operator is involved. It has the same sort of status as a positive number. The third type is an operator, if you write it as an function -(5) it might be more obvious. Dmcq (talk) 10:50, 18 March 2009 (UTC)[reply]

Yep, I see the citation (incidentally, I just changed the link to point straight to page 9), but I'm unconvinced I'm afraid. To pick up on your example, there is no circumstance in which -(5) does not mean exactly the same thing as -5, and for exactly the same reason. "-5" means "minus five" because the minus sign means "take the negative of". Undoubtedly we should give both -5 (say) and -x (say) as examples, but to claim that the minus sign has two different meanings in these two cases is, in my view, more confusing than helpful. 81.129.130.32 (talk) 13:54, 18 March 2009 (UTC).[reply]

It may be more of a technicality in everyday life but mathematically they are quite different, one is the sign part of a number and the other is an arithmetic operator. In computing it does matter because for instance for integers normally there is no positive value corresponding to the maximum negative integer but a person may still want to write the maximum negative integer. Dmcq (talk) 15:28, 18 March 2009 (UTC)[reply]

I understand the issue of a computer being able to hold, say, -32768 as an integer but not +32768, but I don't see how this supports the article's claim that the two uses of the minus sign (in e.g. -5 and -x) are "in mathematics... technically different". It's true that the minus sign in -5 is "the sign part of the number", but the purpose and meaning of that minus sign is mathematically indistinguishable from the purpose and meaning of the minus sign in, say, -x. It's reasonable that these are two different uses I suppose, but far from being "technically different", the two uses are, in my view, actually "technically identical" (in mathematics). Computer implementation issues can go in the "Uses in computing" section. 86.134.30.252 (talk) 21:46, 18 March 2009 (UTC)[reply]

In mathematics -5 is a mathematical object whereas -x is an expression (mathematics). When x is 5 the expression can be evaluated and the value is -5. Expressions are not normally objects except as objects of study in metamathematics. Dmcq (talk) 22:54, 18 March 2009 (UTC)[reply]

I agree that -5 is a number that can be considered as an "entity", but I don't agree that this means the "-" symbol itself has a different meaning compared to, say, -x. To me it's exactly the same meaning, and that's exactly the reason why -5 is written the way it is. -5 means "additive inverse of 5", or "negative of 5", or however you want to put it, and it so happens that the result is another number, a negative one. I think we're just looking at the same thing in two slightly different ways. 86.134.30.252 (talk) 00:06, 19 March 2009 (UTC)[reply]