Remark-math $$ content on single-line is being considered inline math

[pjkaufman]

I am trying to work on formatting some math blocks using remark to identify math blocks as opposed to inline math as the formatting I want to apply is different for each type. The problem is that the following seems to be considered inline math instead of block math:

$$L = \frac{1}{2} \rho v^2 S C_L$$

Here are two places that I have seen references stating that $$ means math block and NOT inline math:

• ASCIIMath plugin and markdown delimiter/format discussion #572
• https://docs.mathjax.org/en/latest/input/tex/delimiters.html#tex-delimiters

Now I could just be doing something wrong or have some kind of format misunderstanding, so I wanted to check here if that was the case.

Here is the AST parser result for the math provided above: https://astexplorer.net/#/gist/111c4f5728f9c80696a9422a7c9c99f0/aa4f9e212560494d7ebb5d826e6777137afa59d1

Here is also how I am reproducing the issue with a clean setup of the package:
package.json

{
  "name": "example",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "type": "module",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "remark-gfm": "^3.0.1",
    "remark-math": "^5.1.1",
    "remark": "^14.0.2",
    "unified": "^10.1.2"
  }
}

examples.md

# Header
$$\boldsymbol{a}=\begin{bmatrix}a_x \\ a_y\end{bmatrix}$$
some more text

$$L = \frac{1}{2} \rho v^2 S C_L$$

examples.js

import fs from "node:fs/promises";
import {visit} from 'unist-util-visit';
import {remark} from 'remark';
import remarkMath from 'remark-math';
import remarkGfm from 'remark-gfm';

const file = await fs.readFile("example.md");
const fileContents = String(file);
const ast = remark().use(remarkGfm).use(remarkMath).parse(file);

console.log(ast)

visit(ast, 'math', (node) => {
  console.log(fileContents.substring(node.position.start.offset, node.position.end.offset) + '\nEND\n')

});

visit(ast, 'inlineMath', (node) => {
  console.log(fileContents.substring(node.position.start.offset, node.position.end.offset) + '\nEND2\n')
});

Here is the output I am getting:

{
  type: 'root',
  children: [
    {
      type: 'heading',
      depth: 1,
      children: [Array],
      position: [Object]
    },
    { type: 'paragraph', children: [Array], position: [Object] },
    { type: 'paragraph', children: [Array], position: [Object] }
  ],
  position: {
    start: { line: 1, column: 1, offset: 0 },
    end: { line: 6, column: 1, offset: 118 }
  }
}
$$\boldsymbol{a}=\begin{bmatrix}a_x \\ a_y\end{bmatrix}$$
END2

$$L = \frac{1}{2} \rho v^2 S C_L$$
END2

I am expecting

{
  type: 'root',
  children: [
    {
      type: 'heading',
      depth: 1,
      children: [Array],
      position: [Object]
    },
    { type: 'paragraph', children: [Array], position: [Object] },
    { type: 'paragraph', children: [Array], position: [Object] }
  ],
  position: {
    start: { line: 1, column: 1, offset: 0 },
    end: { line: 6, column: 1, offset: 118 }
  }
}
$$\boldsymbol{a}=\begin{bmatrix}a_x \\ a_y\end{bmatrix}$$
END1

$$L = \frac{1}{2} \rho v^2 S C_L$$
END1

I am on npm version 8.19.2 and node version v16.16.0.

Please let me know if this is how it is supposed to work. If that is the case, I can manage this by checking to see if the inline math block is surrounded by more than 1 $. But I would like to make sure this is not operator error on my end before I do so.

Thanks for the help!

[wooorm]

Math has no spec. Nobody knows what should happen. Not everyone agrees that what you want, is the way it should happen.

Particularly, in our case, we follow how code works in markdown, with two exceptions:

• dollars instead of backticks
• 2 is also fine for blocks
  Code works like this:

```inline code```

```
block code
```

For more information on how syntax works in our syntax plugins, see the Syntax section in each readme.
In this case: https://github.com/remarkjs/remark-math/tree/main/packages/remark-math#syntax

[pjkaufman]

Gotcha. I looked at the syntax, but never saw it say that a single and multiple dollar signs on a line would be mathInline. But what you say makes sense. I guess I just overlooked the statement somewhere. I will act accordingly with my code. Thanks!

[wooorm]

Yeah, I can understand that. Made it a bit more clear: remarkjs/remark-math@f4596b4. Thanks!

[pjkaufman]

Thanks for that! I did add some comments for very minor grammar things and a question around wether it was the dollar sign count or the new line character that made the math a math block. Thanks again for these wonderful markdown packages!

[Abban-Fahim]

Sorry to disturb this thread, but do you guys have ideas on how to actually support this syntax (of double-dollar signs outputting display math). At one point there was a plugin option to enable it, spawned from remarkjs/remark-math#8, however since remark migrated to micromark, this option was removed.

Any possibility of re-implementing this option, or maybe I can find a way around this. I only really need a way of targeting "inline math" and "double-quote inline math" separately in CSS.

Thanks for any help!

[wooorm]

I only really need a way of targeting "inline math" and "double-quote inline math" separately in CSS.

You can look at ASTs with plugins and change them.

It’s unclear to me what you mean with “inline math” and “double-quote inline math”. What about triple quotes? What about blocks? What is “display” even? Perhaps a new discussion with more info is more useful.