6

I am using lualatex, are there symbols for left and right limits, like small "-" and "+" to put above the numbers? For now I use

\documentclass[a4paper,12pt]{book}
\usepackage{fontspec}
\usepackage{polyglossia}
\usepackage{amsmath,empheq}
\usepackage{mathtools}
\usepackage{amscd}
\usepackage{amsxtra}
\usepackage{unicode-math}                 

\begin{document}
\[
\lim_{x \rightarrow 1^{+}} f(x)
\] 
\[
\lim_{x \rightarrow 1^{-}} f(x)
\]
\end{document}

which I feel is not right because the default "+" and "-" are operators and their size and spacing might not be the best for this use.

5
  • 1
    Have you considered writing \lim_{x\downarrow1} and \lim_{x\uparrow1}, respectively? That should make pretty clear that right-hand ("from above") and left-hand ("from below") limits are being taken.
    – Mico
    May 7, 2015 at 11:20
  • 5
    infix operators like + and - lose their infix status (and the extra space that implies) if used on their own in this way. What you have is the standard markup. May 7, 2015 at 11:27
  • 4
    Note also that TeX doesn't add spaces around binary operation or relation symbols when used in a superscript or subscript; here the situation is even simpler, as @DavidCarlisle says.
    – egreg
    May 7, 2015 at 11:36
  • @Mico thank you, but I prefer to stick with the convention used by my book.
    – Emmet
    May 7, 2015 at 17:50
  • @egreg and David Carlisle, thank you, I already upvoted your comments, if one of you answer the question I can accept it :)
    – Emmet
    May 7, 2015 at 17:55

1 Answer 1

9

Infix operators like + and - lose their infix status (and the extra space that implies) if used on their own in this way. Also as noted by egreg, in a superscript the operators would get no space even used as an infix operator.

What you have is the standard markup.

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