How to get \bm{} to work in an R markdown (to HTML) file?

Question

My R Markdown (.Rmd) file looks like this:

---
title: Foo
author: Marius Hofert
header-includes:
    - \\usepackage{bm}
output:
    pdf_document
vignette: >
          


        

Answer 1

I think your \[ \] and \begin{align} ... \end{align} are redundant. When I ran it as written above I got

! Package amsmath Error: Erroneous nesting of equation structures; (amsmath) trying to recover with `aligned'.

See the amsmath package documentation for explanation. Type H for immediate help. ...

l.84 \end{align}

Worked fine for me when I deleted \begin{align} ... \end{align} ...

(It seems that a similar issue arose in your previous question too ...)

(Perhaps you were getting errors that you didn't notice and were accidentally looking at a previously compiled version?)

---

As far as why you don't get the right HTML output: I'm pretty certain that MathJax (the engine used to render LaTeX embedded in Rmarkdown-produced HTML) doesn't know about \boldmath; adding the package to your LaTeX input won't help, you'll have to use \mathbf and \boldsymbol instead. You can play around here to see what works and what doesn't: entering

$\bm X \boldmath X \boldsymbol X \mathbf X$

at that web page gives

Bottom line, if you want fancy math rendered properly, you're probably better off sticking to PDF output.