我需要类似\underbracket
来自mathtools
包裹:
\documentclass{article}
\usepackage{mathtools}% http://ctan.org/pkg/mathtools
\begin{document}
\[
\underbracket{u'-P(x)u^2-Q(x)u-R(x)}_{\text{=0, since~$u$ is a particular solution.}}
\]
\end{document}
只是我需要在括号的一侧有一个向上的箭头。只要我知道在哪里可以找到要使用的裸箭头,我并不介意自己构造这个符号。但也许其他人已经创建了一个包含此类“下箭头”的包?
下面是我正在寻找的东西的近似例子:
答案1
修改 TikZ 方法这个答案,得到:
\documentclass{article}
\usepackage{amsmath}
\usepackage{tikz}
\newcommand{\tikzmark}[1]{\tikz[overlay,remember picture] \node (#1) {};}
\tikzset{square arrow/.style={to path={-- ++(0,-.25) -| (\tikztotarget)}}}
\tikzset{deep square arrow/.style={to path={-- ++(0,-.5) -| (\tikztotarget)}}}
\begin{document}
\begin{equation}
a\tikzmark{a}x\tikzmark{b}^2 + bx + c = 5\tikzmark{c}x^2 + \tikzmark{d}bx + c.
\tikz[overlay,remember picture]
{\draw[->,square arrow] (c.south) to (b.south);}
\tikz[overlay,remember picture]
{\draw[->,deep square arrow] (d.south) to (a.south);}
\end{equation}
\begin{equation}
a\tikzmark{a}x^2 + bx + c = 5\tikzmark{c}x\tikzmark{b}^2 + \tikzmark{d}bx + c.
\tikz[overlay,remember picture]
{\draw[->,square arrow] (d.south) to (b.south);}
\tikz[overlay,remember picture]
{\draw[->,square arrow] (c.south) to (a.south);}
\end{equation}
\end{document}
得出的结果是:
这正是我所需要的。