mfrac linethickness causes render issues

[andreeapescar]

When linethickness is set, the fractions don't render properly, the line height is wrong ( <math><mrow><mo>-</mo><mfrac linethickness="1"><mn>1</mn><mn>3</mn></mfrac></mrow></math>).

I tried to render in multiple ways:

And this how it renders:

The ones that have linethickness="1" set don't render properly.
(I observed that em is used to render that line.)

Is there any fix for this?
Thank you!

[dpvc]

I'm moving this to the main MathJax issue tracker, so that it is listed with all the other issues.

[dpvc]

The display for linethickness="0" is also correct, as that means there should be no line, which is what you are seeing.

Note that line thickness is a length, and so should either have units or be a named length (like medium). Unitless lengths are deprecated, and are available only for backward compatibility. They are supposed to represent a multiple of the default length, and so in that sense, the result is incorrect, but it turns out that MathJax treats linethickness="1" as linethickness="1em" in this case. That needs to be fixed.

It is not clear what result you are looking for. If linethickness="1" is supposed to produce the normal line thickness, then you could use linethickness="medium". Otherwise, use an explicit unit to get the size you want.

It is possible to use a MathML pre-filter to convert unitless line thickness to multiples of .06em (the size of medium). How that is done differs between version 2 and version 3, so I would need to know which you are using in order to advise you further.

[dpvc]

I've made a pull request to fix the unitless linethickness value in version 3.

[andreeapescar]

Thank you for your quick response!

You are right, The display for linethickness="0" is also correct, I am sorry for that mistake, I will update the issue.

I thought linethickness="1" is supposed to produce the normal line thickness, without having to replace "1" with "medium".

What I need this for:
I get a string like: <math><mrow><mo>-</mo><mfrac linethickness="1"><mn>1</mn><mn>3</mn></mfrac></mrow></math> and I have to render it as html (which I do with dangerouslysetinnerhtml) without having to parse the string.

I am using mathjax-full "^3.0.0".

I assume that after your PR is merged, linethickness="1" will produce normal line thickness, right?

[dpvc]

I thought linethickness="1" is supposed to produce the normal line thickness

It is, but that usage is discouraged by the MathML specification:

"A number without a unit is interpreted as a multiple of the reference value. This form is primarily for backward compatibility and should be avoided, prefering explicit units for clarity."

I assume that after your PR is merged, linethickness="1" will produce normal line thickness, right?

After it is merged, it will be in the develop branch. This will become part of v3.0.2 when develop is merged into master. At that point, the mathjax-full package will be updated, and you can use npm install to get the fixed version.

In the meantime you could use something like

mml = mml.replace(/ linethickness\s*=\s*"([1-9][0-9]*(?:\.[0-9]*)?)"/g, 
          function (match, n) {return ` linethickness="${parseFloat(n)*.06}"`})

in order to work around the problem for now.

[andreeapescar]

Awesome. Thanks a lot for helping! 👍