amsmath constructs not rendering in quarto book

[friendly]

Description

[Env: quarto 1.4.550, RStudio 2024.09.1+394 , Windows 10]

This is related to issue #10545 but different, as it doesn't relate to equation numbering or the things mentioned there.

In my document, I want to use ams \begin{cases} ... \end{cases} to show dummy coding of factors, with the following.
I'm using $$ rather than an equation environment because this shows nicely in my editor window:

$$
x_b = 
\begin{cases}
1 & \text{if factor = b} \\
0 & \text{otherwise}
\end{cases}

;\quad

X_c = 
\begin{cases}
1 & \text{if factor = c} \\
0 & \text{otherwise}
\end{cases}

;\quad

X_d = 
\begin{cases}
1 & \text{if factor = d} \\
0 & \text{otherwise}
\end{cases}
$$

I see onscreen what I want:

Yet, when I render the book, what I see is just:

In my _quarto.yml I'm using mathjax as:

format:
  html:
    html-math-method: mathjax
    theme: cosmo
    code-link: true
    filters:
      - quarto
      - line-highlight
      - parse-latex
      ...

What can I do to make this work?

[friendly]

Ah, it works if I use \begin{equation*} ... \end{equation*}, but then I don't see the result in the editor window.

[mcanouil]

Unfortunately, there are many pieces missing and your screenshots lack context (they also don't have alternative text).
Could you provide a small fully reproducible example and also precise what "on screen" and "render the book" means exactly? What editor? Browser? What format? Is the book project type really a requirement?

Also be aware that you are running a fairly old version of Quarto 1.4.550 which is not even the latest 1.4 stable version.
The current version is 1.7.29.

[friendly]

I'm using R version 4.4.1. I'll upgrade quarto to a more recent compatible version and try this again.

Still, somewhat complicated LaTeX equations are very much part of my work. For simplicity, I'm rendering to HTML and I remain somewhat mystified about mathjax vs. other rendering methods.

[mcanouil]

I'm using R version 4.4.1.

Quarto is unrelated to the R version being used.

Since you are talking about HTML, Mathjax by default can parse environment outside of math mode (see https://docs.mathjax.org/en/latest/options/input/tex.html#the-configuration-block).
All those extra empty lines and line breaks confuse it.

Input	Output
--- title: "Quarto Playground" format: html: html-math-method: mathjax --- $$ x_b = \begin{cases} 1 & \text{if factor = b} \\ 0 & \text{otherwise} \end{cases} ;\quad X_c = \begin{cases} 1 & \text{if factor = c} \\ 0 & \text{otherwise} \end{cases} ;\quad X_d = \begin{cases} 1 & \text{if factor = d} \\ 0 & \text{otherwise} \end{cases} $$

Edit: actually the issue is that you insert paragraph breaks because empty lines are pragraph breaks.
So instead of having one DisplayMath block:

Pandoc
  Meta
    { unMeta =
        fromList
          [ ( "title"
            , MetaInlines [ Str "Quarto" , Space , Str "Playground" ]
            )
          ]
    }
  [ Para
      [ Math
          DisplayMath
          "\nx_b =\n\\begin{cases}\n1 & \\text{if factor = b} \\\\\n0 & \\text{otherwise}\n\\end{cases}\n;\\quad\nX_c = \\begin{cases}\n1 & \\text{if factor = c} \\\\\n0 & \\text{otherwise}\n\\end{cases}\n;\\quad\nX_d = \\begin{cases}\n1 & \\text{if factor = d} \\\\\n0 & \\text{otherwise}\n\\end{cases}\n"
      ]
  ]

This is what you wrote, multiple paragraphs and no math blocks, but MathJax can read begin/end environment and evaluates them.

Pandoc
  Meta
    { unMeta =
        fromList
          [ ( "title"
            , MetaInlines [ Str "Quarto" , Space , Str "Playground" ]
            )
          ]
    }
  [ Plain
      [ Str "$$" , SoftBreak , Str "x_b" , Space , Str "=" ]
  , RawBlock
      (Format "tex")
      "\\begin{cases}\n1 & \\text{if factor = b} \\\\\n0 & \\text{otherwise}\n\\end{cases}"
  , Para [ Str ";" , RawInline (Format "tex") "\\quad" ]
  , Plain [ Str "X_c" , Space , Str "=" ]
  , RawBlock
      (Format "tex")
      "\\begin{cases}\n1 & \\text{if factor = c} \\\\\n0 & \\text{otherwise}\n\\end{cases}"
  , Para [ Str ";" , RawInline (Format "tex") "\\quad" ]
  , Plain [ Str "X_d" , Space , Str "=" ]
  , RawBlock
      (Format "tex")
      "\\begin{cases}\n1 & \\text{if factor = d} \\\\\n0 & \\text{otherwise}\n\\end{cases}"
  , Para [ Str "$$" ]
  ]

See Pandoc Math documentation: https://pandoc.org/MANUAL.html#extension-tex_math_dollars

For display math, use $$ delimiters. (In this case, the delimiters may be separated from the formula by whitespace. However, there can be no blank lines between the opening and closing $$ delimiters.)