How to add Latex packages to markdown?

Question

I am writing some text with Markdown on the Jupyter notebook. But I am not able to import some Latex packages to the notebook. I tried to follow How to include LaTeX package in R Markdown?. I tried to include the mathtools package, but it does not work.

With

title: "Title"
author: "Me"
header-includes:
   - \usepackage{mathtools}
output:
    pdf_document

I am still not able to call commands like $\xrightarrow[\text{sample text}]$ on Jupyter notebook.

Answer 1

Welcome to TeX.SE. Don't use square brackets [] in your math expression. Use braces {} only. You wrote: $\xrightarrow[\text{sample text}]$. It should be: $\xrightarrow{\text{sample text}}$.

Edit: Updated to show the use of \Bracket and \Set from the braket package.

---
title: "Title"
author: "Me"
header-includes:
  - \usepackage{array}
  - \usepackage{booktabs}
  - \usepackage{mathtools}
  - \usepackage{braket}
output:
  pdf_document:
    keep_tex: true
---
```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
```
\hrule <!-- draw a horizontal line -->
We can write in markdown and add content that uses LaTeX syntax and \LaTeX\ packages to format our document.
Using mathtools package
$\xrightarrow{\text{sample text}}$
<br> <!-- add space, like \bigskip % - this is a comment -->
Using array, booktabs and braket packages
\begingroup
\renewcommand*{\arraystretch}{1.7}
\setlength{\tabcolsep}{10pt}
\begin{tabular}{@{}>{\footnotesize}r>{$\displaystyle}l<{$}@{}}
\toprule 
  \verb+\Braket{ \phi | \frac{\partial^2}{\partial t^2} | \psi }+ & \Braket{ \phi | \frac{\partial^2}{\partial t^2} | \psi } \
  \verb+\Set{ x\in\mathbf{R}^2 | 0<{|x|}<5 }+                     & \Set{ x\in\mathbf{R}^2 | 0<{|x|}<5 }                    \
\bottomrule
\end{tabular}
\endgroup
We can do math
result &lt;- 1 + 2
result