![在“案例”环境中需要一个大的积分符号](https://linux22.com/image/389386/%E5%9C%A8%E2%80%9C%E6%A1%88%E4%BE%8B%E2%80%9D%E7%8E%AF%E5%A2%83%E4%B8%AD%E9%9C%80%E8%A6%81%E4%B8%80%E4%B8%AA%E5%A4%A7%E7%9A%84%E7%A7%AF%E5%88%86%E7%AC%A6%E5%8F%B7.png)
答案1
我首选的解决方案是继续使用环境,同时在表达式前立即cases
添加指令。使用环境(我想是“displastyle cases”的缩写;参见以下屏幕截图中的第三个“case”)似乎会鼓励不必要的宽松间距。\displaystyle
\int
dcases
话虽如此,我真的看不出cases
与\textstyle
-mode 积分符号一起使用有什么问题;请参见下面的第一种情况。
\documentclass{article}
\usepackage{mathtools} % loads 'amsmath' automatically
\begin{document}
\begin{align*}
\shortintertext{Case 1: \texttt{cases}}
b_j &=
\begin{cases}
f(x) - \int_{C_j} f & \text{if $x\in C_j$,} \\
0 & \text{otherwise.}
\end{cases}\\
\shortintertext{Case 2: \texttt{cases} with \texttt{\string\displaystyle}}
b_j &=
\begin{cases}
f(x) - \displaystyle\int_{C_j}\! f & \text{if $x\in C_j $,} \\
0 & \text{otherwise.}
\end{cases}\\
\shortintertext{Case 3: \texttt{dcases}}
b_j &=
\begin{dcases}
f(x) - \int_{C_j}\! f & \text{if $x\in C_j$,} \\
0 & \text{otherwise.}
\end{dcases}
\end{align*}
\end{document}
答案2
代码
% My standard header for TeX.SX answers:
\documentclass[a4paper]{article} % To avoid confusion, let us explicitly
% declare the paper format.
\usepackage[T1]{fontenc} % Not always necessary, but recommended.
% End of standard header. What follows pertains to the problem at hand.
\usepackage{mathtools} % also loads "amsmath"
\DeclarePairedDelimiter\abs{\lvert}{\rvert} % unrelated to the issue being
% discussed, but good practice:
% see the manual of the "mathtools"
% package, section 3.6
\begin{document}
\ldots where \( \{W_{\ell}\}_{\ell} \) are sets of dyadic cube [cubes?],
\( x\in W_{\ell} \)
and \( \abs{W_{\ell}} \xrightarrow[\ell\to\infty]{} 0 \).
The function
% I recommend this:
\( b = \sum_{j\in\mathcal{J}} b_{j} \)
% instead of:
% \( b = \sum\limits_{j\in\mathcal{J}} b_{j} \)
% or, still worse:
% \( \displaystyle b = \sum_{j\in\mathcal{J}} b_{j} \)
is given by
\[
b_{j} =
\begin{dcases*}
f(x) - \int_{C_{j}} f & if \( x\in C_{j} \), \\
0 & otherwise.
\end{dcases*}
\]
\end{document}
产生输出
mathtools
有关更多信息,请参阅该软件包的手册第 3.4.3 小节。
答案3
您可以使用(第一个是最好的解决方案,请参阅@Mico 的评论):
1.使用matrix
with 选项\displaystyle
: 肯定比第二个选项的结果更好。
\documentclass[a4paper,12pt]{article}
\usepackage{mathtools}
\begin{document}
\[\left\{\begin{matrix}
f(x)-{\displaystyle \int_{C_j}f} &x\in C\\
0 & \text{otherwise}
\end{matrix}\right.\]
\end{document}
2.或者使用bigints
包裹:
\documentclass[a4paper,12pt]{article}
\usepackage{mathtools}
\usepackage{bigints}
\begin{document}
\[\begin{cases}
f(x)-\bigint_{\!C_j}f& x\in C\\
0 & \text{otherwise}
\end{cases}\]
\end{document}
以下是可能发生的调用的屏幕截图: