# How to add a circle on left/right parentheses?

I need to use a new symbol to denote an operation defining by myself. How to establish a pair of new delimeters just as adding a little circle on left/right parentheses? The difficulty is there are four size of it: \big, \Big, \bigg, \Bigg.

\documentclass{article}
\begin{document}
$\bigl\newlparentheses\sin(x+\pi)\bigr\newrparentheses \cdot\Bigl\newlparentheses\frac ab\Bigr\newrparentheses$
\end{document}


• Welcome to TeX.SX! Please help us to help you and add a minimal working example (MWE) that illustrates your problem. It will be much easier for us to reproduce your situation and find out what the issue is when we see compilable code, starting with \documentclass{...} and ending with \end{document} – user31729 Sep 28 '14 at 9:02
• @Christian Hupfer I've edited my question. Thanks. – delimeterfont Sep 28 '14 at 9:08

You can define new brackets.

For classic \left, \right as

\def\oright#1{\right#1\mskip-10mu\circ}
\def\oleft#1{\circ\mskip-10mu\left#1}


for big \bigl, \bigr as

\def\obigr#1{\bigr#1\mskip-8mu\circ}
\def\obigl#1{\circ\mskip-8mu\bigl#1}


and for extra big \Bigl, \Bigr as

\def\oBigr#1{\Bigr#1\mskip-8mu\circ}
\def\oBigl#1{\circ\mskip-8mu\Bigl#1}


Use it like:

$\oleft(\sin(x+\pi)\oright)$
$\obigl(\sin(x+\pi)\obigr)$
$\oBigl(\sin(x+\pi)\oBigr)$


The result will look like:

• That is good. It will better if the size of circle can change compliable with size of parentheses. – delimeterfont Sep 29 '14 at 5:41