2

We can use \llparenthesis and \rrparenthesis as in the below code, to form circle-segment-shaped brackets:

\documentclass{article}
\usepackage{stmaryrd}

\begin{document}

\begin{equation}

\llparenthesis 2 \rrparenthesis   \quad

\end{equation}

\end{document}

I want to create brackets which are like \llparenthesis and \rrparenthesis except that the circle-segment shapes are filled in with black. How can I do this?

3
  • I don't see anything like that you want in the delimiters section of the comprehensive symbols list, so you will probably need to draw it yourself. – Willie Wong Mar 26 at 14:16
  • Also, to be pedantic, the shape is not a semi-circle, but a segment of a circle. :-) – Willie Wong Mar 26 at 14:18
  • @Willie Wong I don't know how to draw these things. – user65526 Mar 26 at 14:22
3

This is just a first step (and the math gurus here will correct it probably), but as a stopgap:

\documentclass{article}
\usepackage{stmaryrd}
\usepackage{tikz}
\newcommand{\llblob}[2]{
        \tikz [baseline=-#2]\filldraw[x=#1, y=#1] (140:2) arc (140:220:2) -- cycle;%
}
\newcommand{\rrblob}[2]{
        \tikz [baseline=-#2] \filldraw[x=-#1, y=#1] (140:2) arc (140:220:2) -- cycle;%
}
\newcommand{\llfilledp}{\mathopen{\mathchoice
        {\llblob{1ex}{0.7ex}}
        {\llblob{.7ex}{0.4ex}}
        {\llblob{.5ex}{0.4ex}}
        {\llblob{.3ex}{0.2ex}}
}\mkern2mu\relax}
\newcommand{\rrfilledp}{\mathclose{\mkern2mu\mathchoice
        {\rrblob{1ex}{0.7ex}}
        {\rrblob{.7ex}{0.4ex}}
        {\rrblob{.5ex}{0.4ex}}
        {\rrblob{.3ex}{0.2ex}}
}}

\begin{document}

\[
    \llfilledp 2 \rrfilledp A_{\llfilledp 2 \rrfilledp}
\]

\begin{equation}
    \llparenthesis 2 \rrparenthesis  A_{\llparenthesis 2 \rrparenthesis} \quad
\end{equation}

\end{document}

enter image description here

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