# How to make the cases bracket in an equation more elegant?

I am writing an equation containing cases using the following codes:

\begin{equation}
\Delta A =
\begin{cases}
\frac{\pi \left( 1-\mu \right) d_i^2}{42GW_c} & \text{if } a = 0\\
0                                  & \text{if } a = 1
\end{cases}
\end{equation}


It worked fine but the output is not beautiful, I want to make the left brace smaller, could someone tell me how to deal with it? • Welcome to TSE. Please post a Minimal Working Example, instead of a code snippet. Sep 24, 2021 at 9:11
• Thank you @JoséCarlosSantos, I am using the elsevier double column template, should I attach the whole template files? Sep 24, 2021 at 9:20
• No, just MWE (Minimal Working Example, a small but complete document, which produce showed equation. "Elegancy" of your bracket depends on used font ... and its very opinion based. To me looks fine, will be nicer if it will a bit less tall. Sep 24, 2021 at 9:23
• If you use cas-dc documentclass, then you should write into the first line the next: \PassOptionsToPackage{nomath}{stix} Sep 24, 2021 at 10:00

Maybe the brace obtained with empheq will be more like you want?

\documentclass{article}
\usepackage{empheq}

\begin{document}

\begin{empheq}[left={\Delta A =\empheqlbrace}]{equation}
\begin{aligned}
&\frac{\pi \left( 1-\mu \right) d_i^2}{42GW_c} & & \text{if } a = 0\\[1ex]
& 0 & & \text{if } a = 1
\end{aligned}
\end{empheq}

\end{document}  The output by the conventional cases looks good, but it is possible to do this with tikz and nicematrix to provide flexibility in adjusting the braces thickness to your taste.

\documentclass{amsart}
\usepackage{nicematrix}
\usepackage{tikz}

\usetikzlibrary{decorations.pathreplacing,calligraphy}

\tikzset{
BraceMirrored/.style = {decorate,
decoration={calligraphic brace, amplitude=2pt,
pre =moveto, pre  length=1.1pt,
post=moveto, post length=1.1pt,
mirror,
raise=#1},
thick,
pen colour=black},
BraceMirrored/.default=0pt
}

\begin{document}

\begin{equation*}
\everymath{\displaystyle}
\Delta A = \mspace{11mu}
\frac{\pi \left( 1-\mu \right) d_i^2}{42GW_c} & \text{if $a = 0$}
\\
0 & \text{if $a = 1$}
\CodeAfter
{
\begin{tikzpicture}
\draw[BraceMirrored={3.7pt}, thin] (1-1.north west) -- node[left=3.7pt] {} (2-1.south west); % change thickness by including thin, 'very thin', or 'ultra thin'
\end{tikzpicture}
}
\end{NiceArray}
\end{equation*}

\end{document} Is this what You need?

\documentclass{extreport}
\usepackage{amsmath}

\begin{document}

\begin{equation}
\Delta A =
\begin{cases}
\dfrac{\pi \left( 1-\mu \right) d_i^2}{42GW_c} & \text{if } a = 0\\
0                                  & \text{if } a = 1
\end{cases}
\end{equation}

\end{document}


In the Elsevier's double column template, the cas-dc documentclass loads the stix package, which causes your problem. If you write \PassOptionsToPackage{nomath}{stix} into the first line of the source, this effect will be disappeared.