Quick and simple question (actually surprised I couldn't find it on Stackexchange already): How can I typeset (in math mode) quantities with a tilde on top that is enclosed in parentheses?
Something akin to this would be nice:
I hope there's a solution without (a lot of) manual tinkering that clutters up my preamble
How about this:
\documentclass{article}
\newcommand\ptwiddle[1]{\mathord{\mathop{#1}\limits^{\scriptscriptstyle(\sim)}}}
\begin{document}
$\ptwiddle{A} + \ptwiddle{B} = \ptwiddle{C}$
\end{document}
Since I've hard coded the \scriptscriptstyle size, this might not look so good in a subscript.
I came across this topic because I was looking for a solution to the same problem as the OP. Although the proposed solution worked, I was not really satisfied with the result, especially because the parentheses and the tilde were still quite chubby. Unlike originally wished by the OP, cluttering up my preamble was not a problem for me.
What I ended up doing instead is:
1) Use @Pieter van Oostrum 's answer to establish a nicer widetilde in the first place. The block below the first comment in my code is completely taken over from his solution.
2) I then combined this with ideas from @Alenanno 's post here to also write a command that furthermore puts said widetilde in parentheses.
The resulting commands \fixwidetilde{...} and \parwidetilde{...} gave the best results for my purposes. Note that parts (the first four lines) of the block below my first comment are necessary for the definition of the \parwidetilde{...} command. If \fixwidetilde{...} is not needed, one may without problems adjust the code by removing its definition from the code.
Below is a MWE:
\documentclass{article}
\usepackage{amsmath}
\usepackage{accents}
\usepackage{mathtools}
% A nicer \widetilde{...} with \fixwidetilde{...}
\DeclareMathSymbol{\widetildesym}{\mathord}{largesymbols}{"65}
\newcommand\lowerwidetildesym{%
\text{\smash{\raisebox{-1.3ex}{%
$\widetildesym$}}}}
\newcommand\fixwidetilde[1]{%
\mathchoice
{\accentset{\displaystyle\lowerwidetildesym}{#1}}
{\accentset{\textstyle\lowerwidetildesym}{#1}}
{\accentset{\scriptstyle\lowerwidetildesym}{#1}}
{\accentset{\scriptscriptstyle\lowerwidetildesym}{#1}}
}
% Overset the above tilde in brackets with \parwidetilde{...}
\newcommand\parwidetilde[1]{%
\mathchoice
{\accentset{\displaystyle\scalebox{.3}{(}\lowerwidetildesym\scalebox{.3}{)}}{#1}}
{\accentset{\textstyle\scalebox{.3}{(}\lowerwidetildesym\scalebox{.3}{)}}{#1}}
{\accentset{\scriptstyle\scalebox{.3}{(}\lowerwidetildesym\scalebox{.3}{)}}{#1}}
{\accentset{\scriptscriptstyle\scalebox{.3}{(}\lowerwidetildesym\scalebox{.3}{)}}{#1}}
}
\begin{document}
\begin{align}
\fixwidetilde{A} + \parwidetilde{B} &= C \notag \\
\fixwidetilde{ABC} + \parwidetilde{DEF} &= GHI
\end{align}
\end{document}
And here You can see the result:
Even though the question is from four years ago, I add my answer keeping in mind that accents package vertically aligns the symbols more accurately. See the example.
\documentclass[a4paper,12pt]{article}
\usepackage{mathtools}
\usepackage{amssymb}
\usepackage{accents}
\begin{document}
\[\accentset{\scriptscriptstyle{(\sim)}}{A}+\accentset{\scriptscriptstyle{(\sim)}}{B}=\accentset{\scriptscriptstyle{(\sim)}}{C}*\accentset{\scriptscriptstyle{(\sim)}}{D}\]
\end{document}
