![标记向量中的条目位置](https://linux22.com/image/379724/%E6%A0%87%E8%AE%B0%E5%90%91%E9%87%8F%E4%B8%AD%E7%9A%84%E6%9D%A1%E7%9B%AE%E4%BD%8D%E7%BD%AE.png)
我可能通过举例来解释我的问题。例如,
Let $e_i=(0,\ldots,0,1,0,\ldots,0)$ be the standard basis
vector for n-dimensional Euclidean space $\mathbb{R}^n$.
通过画一条小线并写下$i^{th}$
-entry,我想给出该向量中条目的位置。
答案1
我想你想要这样的东西:
\documentclass{article}
\usepackage{amsmath, amsfonts}
\usepackage{tikz}
\usetikzlibrary{positioning, arrows.meta}
\newcommand{\here}[2]{\tikz[remember picture]{\node[inner sep=0](#2){#1}}}
\begin{document}
Let
\[
e_i=(0,\ldots,0,\here{1}{fromhere},0,\ldots,0)
\]
\begin{tikzpicture}[remember picture, overlay]
\node[font=\scriptsize, below right=12pt of fromhere] (tohere) {$i^{th}$-entry};
\draw ([yshift=-4pt]fromhere.south) |- (tohere);
\end{tikzpicture}
\bigskip\noindent%
be the standard basis
vector for n-dimensional Euclidean space $\mathbb{R}^n$.
Let
\[
e_i=(0,\ldots,0,\here{1}{fromhere},0,\ldots,0)
\]
\begin{tikzpicture}[remember picture, overlay]
\node[font=\scriptsize, below right=12pt of fromhere] (tohere) {$i^{th}$-entry};
\draw[<-] ([yshift=-4pt]fromhere.south) |- (tohere);
\end{tikzpicture}
\bigskip\noindent%
be the standard basis
vector for n-dimensional Euclidean space $\mathbb{R}^n$.
Let
\[
e_i=(0,\ldots,0,\here{1}{fromhere},0,\ldots,0)
\]
\begin{tikzpicture}[remember picture, overlay]
\node[font=\scriptsize, below right=12pt of fromhere] (tohere) {$i^{th}$-entry};
\draw[Stealth-] ([yshift=-4pt]fromhere.south) |- (tohere);
\end{tikzpicture}
\bigskip\noindent%
be the standard basis
vector for n-dimensional Euclidean space $\mathbb{R}^n$.
Let
\[
e_i=(0,\ldots,0,\here{1}{fromhere},0,\ldots,0)
\]
\begin{tikzpicture}[remember picture, overlay]
\node[font=\scriptsize, below right=12pt of fromhere] (tohere) {$i^{th}$-entry};
\draw[Latex-] ([yshift=-4pt]fromhere.south) |- (tohere);
\end{tikzpicture}
\bigskip\noindent%
be the standard basis
vector for n-dimensional Euclidean space $\mathbb{R}^n$.
\end{document}