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This question already has an answer here:

I am writing a document about limits of functions. I need to use notation for the lower limit, which I have as the normal limit sign but with 'lim' underlined. I need the same for the upper limit with 'lim' overlined.

For the overlined I have tried to use

\overline{\lim_{x \to 0^{+}}}

but that overlines all of it, I just want it over the 'lim' part.

marked as duplicate by GuM, Bernard, Stefan Pinnow, Mike Renfro, ebosi May 30 '17 at 23:39

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    Don't reinvent the wheel: it already exists in the amsmath package under the name of \varliminf. See my answer to this question for this symbol and a few others in the same style. (lim sup, direct and inverse limits). – Bernard May 30 '17 at 21:58
  • @Bernard: Of course!! (;-) So, this question should probably be marked as a duplicate, shouldn’t it? – GuM May 30 '17 at 22:07
  • @Gustavo Mezzetti: It's also my opinion. – Bernard May 30 '17 at 22:09
  • @Bernard: Done. But probably, you have got a gold badge that allows you to bypass the vote. – GuM May 30 '17 at 22:12
  • @Gustavo Mezzetti: I don't how to do that. I simply voted to close (which I rarely do). – Bernard May 30 '17 at 22:14
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Not a notation I recognise, but

enter image description here

\documentclass{article}

\usepackage{amsmath}

\DeclareMathOperator*\lowlim{\underline{lim}}
\DeclareMathOperator*\uplim{\overline{lim}}

\begin{document}

\[
\lim_{x \to 0^{+}} \rightarrow
\lowlim_{x \to 0^{+}} \rightarrow
\uplim_{x \to 0^{+}}
\]

\end{document}
  • Ah, thank you. It's not notation I particularly like, but I couldn't think of a better one. – JSharpee May 30 '17 at 19:53
  • It's not my notation. I am reading a book by Kenneth Falconer. – JSharpee May 30 '17 at 19:56
  • @JSharpee Sorry! I misunderstood your comment, I deleted earlier comment (I still don't like the notation much though:-) – David Carlisle May 30 '17 at 19:57
  • Aha, that's ok. I don't either. Thank you for your help. – JSharpee May 30 '17 at 19:59
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    @JSharpee: Speaking of better notations, of course you know that LaTeX has \liminf and \limsup, which yield “lim inf” and “lim sup”, respectively, don’t you? – GuM May 30 '17 at 22:01
0

Oddly enough, this works:

$\overline{\lim}_{x \to 0^{+}}$

And it looks like this:

Bar over lim

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    that loses the mathop classification, so gets different spacing and the limit comes in subscript position not underneath as it does for \lim – David Carlisle May 30 '17 at 19:50
  • Huh. That is weird and disturbing that it works. I will use the answer above if that's ok. Thanks though. – JSharpee May 30 '17 at 19:51

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