bracesnesting
How can I adjust the size of the outer braces to make the following equation neater?
\documentclass[a4paper]{scrreprt}
\usepackage{amsmath}
\begin{document}
\[
M = \left\{ x \in X :
\begin{cases} p(x) > 0 \\ q(x) > 0 \end{cases}
\right\}
\]
\end{document}
use package mathtools. There is also a drcases environment
\documentclass{article}
\usepackage{mathtools}
\begin{document}
\[
\begin{rcases*}
E = m c^2 & foo \\
\int x-3\, dx & barbaz
\end{rcases*} y=f(x)
\]
\end{document}
I would say that with numcases the brace is a bit too low. Nevertheless, I fully agree that the braces with aligned and cases are much too large. Here's what I often do as a remedy:
\documentclass{article}
\usepackage{amsmath}
\makeatletter
\def\env@cases{%
\let\@ifnextchar\new@ifnextchar
\left\lbrace
\def\arraystretch{1.1}%
\array{@{\,}l@{\quad}l@{}}%
}
\makeatother
\begin{document}
\[
\begin{cases}
x=x, \\
u=u(x,t).
\end{cases}
\quad
\begin{cases}
a=a, \\
x=x, \\
u=u(x,t).
\end{cases}
\quad
\begin{cases}
a=a, \\
b=b, \\
x=x, \\
u=u(x,t).
\end{cases}
\]
\end{document}
The point is that amsmath's cases uses an \arraystretch of 1.2, which doesn't work well with TeX's standard brace sizes. I prefer using 1.1 instead of 1.2; of course this means that there's a bit less vertical space between the cases. Maybe you'll deem the braces still too large, but in my opinion this is a good compromise. (The distance to the brace tips appears a bit large only because a, x and u don't have ascenders and descenders.)
Best Answer
As shown that is a global setting, it can be set locally within a single expression (or a single
{}group) if needed. Also you can experiment with different lengths5ptis the default.