A post Mathematical formulation of beam: get stress/strain from forces and momentum uses \overline{\overline{…}}. The results below are mostly from Safari 16.1 on macOS 12.6.1, but casual experimentation suggests that, with one exception, they are not terribly browser-dependent.

Using HTML-CSS (Common HTML is almost identical):

HTML-CSS double overline

Using Preview HTML:

Preview HTML double overline

Using SVG:

SVG double overline

Using MathML on Safari:

MathML on Safari double overline

Using MathML on Firefox 107.0.1:

MathML on Firefox double overline

The spacing of "MathML on Firefox" is the correct one (by comparing to a separate TeX installation). I am a bit surprised that the SVG spacing is incorrect, since I thought that just compiled it in an external process and just inserted an image of the resulting rendered equation.


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StackExchange hasn't upgraded the version of MathJax that they are using in quite some time. They are using v2.7.5, which is more than 4 years old. The current version is 3.2.2, which handles the double overline much better.

Here is MathJax v3:

MathJax v3

compared to actual LaTeX:

Actual LaTeX

MathJax v4.0 is in alpha release, so even version 3 won't be current for long. It would be nice it StackExchange upgraded their version of MathJax, even if it is only to the highest version 2 (which is v2.7.9).

Your supposition that SVG output is based on an image generated on the server by running actual TeX is incorrect. The SVG output is created in the browser by MathJax on the fly, just as all the other output formats are.

Note that the MathML renderings get the spacing between the delta and the following letter wrong in the partial derivatives.

  • $\begingroup$ Re: It would be nice it StackExchange upgraded their version of MathJax. A moderator marked this feature request on Mathematics Meta as (status-review): MathJax out of date. At the same time, some people suggested in the comments that it might be worth waiting for v4 - since it is supposed to come soon. $\endgroup$ Commented Dec 19, 2022 at 12:46
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    $\begingroup$ @MartinSleziak, one of the reasons that SE hasn't upgraded is that v3 didn't include the automatic line breaking support. That is included in v4, so waiting for that is reasonable (should be early 2023). But the v3/v4 API is different from the v2 API, and that will require changes to the SE code that calls MathJax, and that may take time and testing, so I would recommend starting the process now with v3 (the v4 API is the same as v3), so that when v4 is out, SE will be ready to go. $\endgroup$ Commented Dec 19, 2022 at 13:22
  • $\begingroup$ @DavideCervone Would you consider posting the stuff you've mentioned in this comment as an answer to the linked thread on Mathematics Meta? (Perhaps it could be useful if more people see this information.) $\endgroup$ Commented Dec 19, 2022 at 13:26
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    $\begingroup$ @MartinSleziak, I have made a post there, as you requested. $\endgroup$ Commented Dec 21, 2022 at 23:10

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