为矢量元素绘制箭头

Question

我想从向量的不同元素绘制垂直向下的箭头。我修改了代码指向方程式的箭头。

有人能告诉我为什么最右边的箭头没有放在中间低价处吗？其次，如果整体外观可以改善，我将不胜感激。此外，'$\bm{v}$' 不会显示为粗体斜体，如下所示。

这是代码

\documentclass{beamer}
\usetheme{default}
\usecolortheme{default}
\usepackage[english]{babel}
\usepackage{amsmath,amsfonts,amssymb,amsthm}
\usepackage{mathptmx}
\usepackage{calc}
\usepackage{tikz}
\usepackage{mathtools,mathdots,bm,fixltx2e}
\usetikzlibrary{tikzmark,calc,,arrows,shapes,decorations.pathreplacing}
\tikzset{every picture/.style={remember picture}}
\usepackage{accents}

\newcommand\myubar[1]{%
\underaccent{\bar}{#1}}

\begin{document}

\begin{equation*}
\tikz[baseline]{\node(a) {$\bm{v}$}} = [\quad \tikz[baseline]{\node(b){$I_{E(x_3)}$}} , \tikz[baseline]{\node(c) {$c$}},\tikz[baseline]{\node(d){$\underbrace{I_{E(x_1)},\cdots,I_{E(x_2)}}$}} , \tikz[baseline]{\node(e){$\underbrace{I_{E(y_2)},\cdots,I_{E(y_3)}}\quad$}}]
\end{equation*}

\begin{tikzpicture}[remember picture,overlay]
\draw[blue,thick,->] (b) to [in=90,out=270] + (270:4cm) node[anchor=north,text = black,text width=3cm,align=center] {ABC\\DEF};
\draw[blue,thick,->] (c) to [in=90,out=270] +(270:2cm) node[anchor=north,text = black,text width=3cm,align=center] {GHI\\JKL};
\draw[blue,thick,->] (d) to [in=90,out=270] +(270:3cm) node[anchor=north,text = black,text width=3cm,align=center]{MNO\\ PQR \\ (xxx)};
\draw[blue,thick,->] (e) to [in=90,out=270] +(270:2cm) node[anchor=north,text = black,text width=3cm,align=center]{STU\\ VWY \\ (yyy)};
\end{tikzpicture}

\end{document}

输出：

Answer 1

正如评论中所述，该字体是典型的 beamer 字体，箭头位置错误是由于\quad。为了改善整体外观，我建议不要将所有内容都放在基线上。我还希望所有箭头都从同一水平开始。

\begin{frame}
  \begin{displaymath}
    \bm{v} 
    = \Bigl[%
    \tikz[remember picture,inner sep=0pt]\node (b1) {\smash{$\displaystyle I_{E(x_3)}$}};,
    \tikz[remember picture,inner sep=0pt]\node (c1) {\smash{$\displaystyle c$}};, 
    \underbrace{I_{E(x_1)},\cdots,I_{E(x_2)}}_{\tikz[remember picture]\coordinate (d1) at (0,0);}, 
    \underbrace{I_{E(y_2)},\cdots,I_{E(y_3)}}_{\tikz[remember picture]\coordinate (e1) at (0,0);}\Bigr]
  \end{displaymath}
  \begin{tikzpicture}[remember picture,overlay]
    \draw[blue,thick,->] (b1|-d1) to [in=90,out=270] + (270:2.5cm) node[anchor=north,text = black,text width=3cm,align=center] {ABC\\DEF};
    \draw[blue,thick,->] (c1|-d1) to [in=90,out=270] +(270:1cm) node[anchor=north,text = black,text width=3cm,align=center] {GHI\\JKL};
    \draw[blue,thick,->] (d1) to [in=90,out=270] +(270:2cm) node[anchor=north,text = black,text width=3cm,align=center]{MNO\\ PQR \\ (xxx)};
    \draw[blue,thick,->] (e1) to [in=90,out=270] +(270:1cm) node[anchor=north,text = black,text width=3cm,align=center]{STU\\ VWY \\ (yyy)};
  \end{tikzpicture}
\end{frame}