Can I strike out text in an equation in R markdown

Question

I have an equation that I wrote in r-markdown as follows

$$ 2 \frac{meter}{day} * 3 ~ days $$

I'd like to show that the days cancel by striking them out. You can strike out text in r-markdown normally by ~~surrounding the text in tildaes~~

However, the tildae in the expression seems to only insert spaces.

$$ 2 \frac{meter}{~~day~~} * 3 ~ ~~days~~ $$

I also tried as one might in latex

$$ 2 \frac{meter}{sout{day}} * 3 ~ days $$

But this doesn't seem to work either.

Are there any options for striking out bits of equation that work in r-markdown equations?

Cirrhosis

You're missing a backslash for \sout – Haemoid

Answer 1

For PDF output you can use the LaTeX style cancel:

---
header-includes: \usepackage[makeroom]{cancel}
output: pdf_document
---

$$ 2 \frac{\text{meter}}{\cancel{\text{day}}} * 3 ~ \cancel{\text{days}} $$

Result:

Note that the usage of \text is unrelated to your question and only used for typographical reasons.

Unfortunately this does not work with HTML output.

Washbowl

When I add the header you have suggested on the header of the markdown document it stops the stops the creation of the pdf with the following error message ... ! Undefined control sequence. <argument> \cancel – Drupelet

@Drupelet Does the minimal example that I posted work for you? Does your TeX system have the cancel.sty installed? – Washbowl

@Ralph It generates the error message that I mentioned above. I am running markdown using RStudio on a Mac and my tex live utility includes the cancel package. – Drupelet

@Drupelet Please update the test document to keep the TeX file (c.f. https://mcmap.net/q/580006/-rmarkdown-retain-tex-file) and check that the resulting TeX file contains \usepackage[makeroom]{cancel}. – Washbowl

@Ralph I looked at the TeX file and its does not contain the package. Can you please help/tell me on how to add it? – Drupelet

@Drupelet The header-includes YAML header should take care of that. Very odd. As an alternative you can write that line into a file and include it via includes, c.f. bookdown.org/yihui/rmarkdown/pdf-document.html#includes-1. – Washbowl

@Ralph Adding the line \usepackage[makeroom]{cancel} in the file preamble.tex did this for me. Thank you for your help. – Drupelet

I have \usepackage[makeroom]{cancel} listed in header-includes but I had to add additionally $$\require{cancel} ... $$ in the equation to make it work. – Pseudaxis

Answer 2

For HTML, add at the beginning of the markdown,

<script type="text/x-mathjax-config">
MathJax.Hub.Register.StartupHook("TeX Jax Ready",function () {
  MathJax.Hub.Insert(MathJax.InputJax.TeX.Definitions.macros,{
    cancel: ["Extension","cancel"],
    bcancel: ["Extension","cancel"],
    xcancel: ["Extension","cancel"],
    cancelto: ["Extension","cancel"]
  });
});
</script>

and then

$$2 \frac{\text{meter}}{\cancel{\text{day}}} * 3 ~ \cancel{\text{days}}$$

will work

Ohmage

I am using markdown to write a book and one of my chapters has an equation where I am using strike through font. When you say add the script at the beginning of the markdown do you mean to add this at the top of the relevant chapter? I tried it and it does not work. Thanks – Drupelet