What is the difference between \ldots and \cdots?
For example, To write a sequence of points which is best to use?
a_1,\ldots,a_n Or a_1,\cdots,a_n.
Couple of examples of the difference can be useful.
2 Answers
Although I agree with egreg's comment, the difference is mainly of an aesthetic nature imo.
It depends on the context which version to use, which is also how amsmath decides which to use.
Some examples:
a_1,\ldots,a_n aligns better than a_1,\cdots,a_n.
But a_1 \to \ldots \to a_n aligns worse than a_1 \to \cdots \to a_n.
The alignment chosen by amsmath is usually the one commonly found in mathematical articles. However, I guess its not really wrong or anything to deviate from it.
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2while some authors may deviate from the "usual" pattern, a copyeditor trained in math tradition will mark deviations except in very special cases.
amsmathwas constructed to follow traditional typographic usage (which is, as noted, based largely on alignment, to avoid calling attention to its appearance and thus away from the underlying meaning). Commented Jun 5, 2013 at 12:28 -
3I am told that the standard practice is to use
\ldotswhen the separator symbol is bottom-aligned (eg: comma ) and to use\cdotswhen the separator symbol is at center-aligned (eg:\to) Commented Aug 8, 2019 at 5:50 -
@CyriacAntony that is exactly what I use
\ldotsand\cdotsfor.– ᴇɴᴅᴇʀᴍᴀɴCommented Jul 6, 2022 at 16:38 -
I back this suggestion; tex.stackexchange.com/a/77742/157031 (already pointed out by egreg in comment to the question) Commented Jul 7, 2022 at 0:57
Idots are used between the comma's (at the bottom) where as cdots are used between mostly in plus minus signs (at the middle of the line).
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1Good question, I don't know why it was downvoted either! Lemme upvote it to balance it out a bit :)– ᴇɴᴅᴇʀᴍᴀɴCommented Jul 6, 2022 at 16:35
amsmathand use\dots; in the vast majority of cases, the result will be what's usually found in mathematical publications.