6

When I type \biggl\lparen before \int\limits, where \limits puts the domain over which I'm integrating under the integral sign, the bottom end of the left parenthesis touch — or is too close to — the domain symbol ; and it causes poor readability.

Here is an example :

\biggl\lparen \int\limits_{\{\lvert x \rvert > R \}} u(x) dx \biggr\rparen

I have overcome this difficulty by adding a space after the left parenthesis with \>. More precisely, I defined the following PairedDelimiter :

\DeclarePairedDelimiterX{\parens}[1]{\lparen}{\rparen}{\> #1}

However, I am not satisfied by this « solution » because I do not need the extra spacing all the time, and that makes \parens not flexible at all.

I don't want to use \left and \right, since they make the parentheses too big ; nor \Bigl and \Bigr which make the parentheses too small.

I'm open to any suggestion.

Thanks !

  • Welcome to TeX.SX! You can have a look at our starter guide to familiarize yourself further with our format. – karlkoeller Feb 24 '15 at 17:10
  • Maybe you would be happier with \[\biggl(\int\limits_{\mathrlap{\{|x|>R\}}} u(x)\,\mathrm{d}x\biggr)\]? This requires the package mathtools instead of amsmath. We do not know, what you use, due to the missing MWE. – LaRiFaRi Feb 24 '15 at 17:19
  • 3
    @LaRiFaRi \lparen and \rparen are defined by mathtools – karlkoeller Feb 24 '15 at 17:22
  • @karlkoeller thanks. Never seen them. I will have to read about those. Can't see their advantage in the OP. – LaRiFaRi Feb 24 '15 at 17:23
  • @karlkoeller Thanks. I should have done that before posting. My apologies! – Gatz Feb 25 '15 at 10:20
6

Since it looks like you're using the mathtools package (good move!), I suggest you do the following:

  • use the \smashoperator[r]{...} directive (provided by the mathtools package) to eliminate the whitespace between the integral symbol and the integrand;

  • define a new macro called \abs using \DeclarePairedDelimiter;

  • define the macro \parens using \DeclarePairedDelimiter as well, and use \parens[\bigg]{...} to generate the bigg-sized parentheses;

  • insert a thinspace between the integrand and dx; optional: write \mathrm{d}x if you want the "differential operator" set in upright rather than in italic mode;

  • add a bit of whitespace after \biggl\lparen to separate visually the large opening parenthesis from the domain of integration (\,\, seems about right to me, but your preferences may differ); and

  • omit the curly braces around the expression for the domain of integration.

enter image description here

\documentclass{article}
\usepackage{mathtools}
\DeclarePairedDelimiter{\abs}{\lvert}{\rvert}
\DeclarePairedDelimiter{\parens}{\lparen}{\rparen}
\begin{document}
\begin{align*}
\texttt{before:}&\quad
\biggl\lparen \int\limits_{\{\lvert x \rvert > R \}} u(x) dx \biggr\rparen\\[2ex]
\texttt{after:}&\quad
\parens[\bigg]{\,\, \smashoperator[r]{\int\limits_{\abs{x}> R }} u(x) \, dx }
\end{align*}
\end{document} 

Addendum: In a follow-up comment, the OP mentioned that he/she uses the mathptmx package, and that \bigg-sized parentheses turn out to be too big and that \Big-sized parentheses are not big enough. I suggest looking into using the MathTime Professional II font package, which provides high-quality math fonts based on Times Roman. (The complete mtpro2 package isn't free of charge. However, its "lite" subset, which is all that's needed for the present example, is free of charge.)

enter image description here

\documentclass{article}
\usepackage{newtxtext}    % Times Roman text font
\usepackage[lite]{mtpro2} % Times Roman math font
\usepackage{mathtools}
\DeclarePairedDelimiter{\abs}{\lvert}{\rvert}
\DeclarePairedDelimiter{\parens}{\lparen}{\rparen}
\begin{document}
\[
\parens[\bigg]{\mkern6mu \smashoperator[r]{\int\limits_{\abs{x}> R }} \! u(x) \, dx }
\]
\end{document} 

One may also give the newtxmath package (load it with the option cmintegrals) a try. In my opinion, though, the large parentheses produced by newtxmath look rather anemic; they're certainly not as handsome as those that are produced by the mtpro2 package. Moreover, it's necessary to use \Bigg as the sizing directive the parentheses.

enter image description here

(Same code as in the preceding MWE, with \usepackage[lite]{mtpro2} replaced with \usepackage[cmintegrals]{newtxmath}, and with \Bigg instead of \bigg as the sizing instruction.)

  • Thanks a lot! I'm using the package mathptmx (Times New Roman) and I just found out that the parentheses are a bit longer than in Computer Modern ; this is why they overlap the integration domain when there are no extra spaces. Any suggestion? – Gatz Feb 25 '15 at 10:34
  • @Gatz - With mathptmx loaded, I think it would be perfectly OK to use \Big as the sizing instruction, i.e., to write \parens[\Big]{\,\, ...}. \bigg definitely generates parentheses that are overly tall. Note that I'd still use \,\, -- or, equivalently, \mkern6mu -- to insert some added whitespace following the opening left parenthesis. – Mico Feb 25 '15 at 10:46
  • Unfortunately, \Big is a bit too short: the bottom end of the left parenthesis doesn't go between the bottom end of the integral sign and the integration domain. I don't know if my explanations are clear... However, is it possible to use the Times font for the text and the Computer Modern font for the math mode? Thanks! – Gatz Feb 25 '15 at 10:56
  • @Gatz - I would not try to mix-and-match Times Roman and Computer Modern; they are just too different along various dimensions. By the way, it is not absolutely necessary (typographically speaking) for the parentheses to be at least as tall as the integral symbol that they enclose. It's purely a matter of taste. – Mico Feb 25 '15 at 11:11
  • Ok. However, I'll give newtxtext a try. Many thanks for your help! – Gatz Feb 25 '15 at 12:52
3

Mico has already given some nice ideas which provide a beautiful result. However, I am posting my idea from comment as well, as it is quite short and might serve you here:

% arara: pdflatex

\documentclass{article} 
\usepackage{mathtools}
\DeclarePairedDelimiter{\abs}{\lvert}{\rvert}

\begin{document} 
    \[\biggl(\int\limits_{\mathrlap{\abs{x}>R}} u(x)\,\mathrm{d}x\biggr)\]
\end{document} 

enter image description here

  • +1, but remove the braces... – karlkoeller Feb 25 '15 at 8:18
  • @karlkoeller done. But I think they were wanted by the OP. Well, no problem to add them again... – LaRiFaRi Feb 25 '15 at 8:37

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