How to typeset this symbol with \mathcal?

Question

I want to typeset the symbol $(C_m)$ by using \mathcal, I tried

\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{calrsfs}
\usepackage[left=2cm,right=2cm,top=2cm,bottom=2cm]{geometry}
\usepackage[mathscr]{euscript}
\begin{document}
$\mathcal{(C}_m)$ 
\end{document}

The results are not beautiful. I can not use $\mathcal{(C_m)})$ How can I typeset this symbol?

Answer 1

\mathcal only works for upper case letters, so you could use

$(\mathcal{C}_m)$

If you need the lower case "m" to be in a similar font, you can load the calligra package and define a \mathcalligra command in the form

\usepackage{calligra}
\DeclareMathAlphabet{\mathcalligra}{T1}{calligra}{m}{n}

A complete example:

\documentclass[12pt,a4paper]{article}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{calligra}
\usepackage{calrsfs}
\usepackage[left=2cm,right=2cm,top=2cm,bottom=2cm]{geometry}
\usepackage[mathscr]{euscript}

\DeclareMathAlphabet{\mathcalligra}{T1}{calligra}{m}{n}

\begin{document}

$(\kern-4pt\mathcalligra{C_m}\kern1pt)$

$(\mathcal{C}_m)$

\end{document}