MathJax Whiplash

Written by: Paul Rubin

Primary Source:  OR in an OB World

Technology is continuously evolving, and for the most part that’s good. Every now and then, though, the evolution starts to look like a random mutation … the kind that results in an apocalyptic virus, or mutants with superpowers, or something else that is much more appealing as a plot device in a movie or TV show than in real life.

Back in 2010 I switched math rendering in this blog to MathJax, and things went swimmingly … for a while. Then rendering got glitchy in Firefox (I forget exactly when), and I ended up installing a trio of Firefox extensions (MathML-Fonts, MathML Font Settings, and Native MathML), which fixed things … for a while.

Last December things got goofy again. Math formulas were causing excess vertical space to appear between lines. Google Chrome was unaffected; I only saw this in Firefox. (I never use Internet Exploder, Safari or Opera, and don’t use Chromium very often, so I have no idea if any of them were affected.) As I noted in an otherwise unrelated post, the problem seemed to cure itself while I was busy searching for help, so I never knew what caused it or, for that matter, what cured it. No matter; rendering once again worked properly … for a while.

A week or so ago, I noticed that the vertical spacing issue had returned. Today I finally took the time to go looking for help. The closest I came to a fix was finding information in a MathJax FAQ that the configuration I was using in the blog had been deprecated as of MathJax v2.6. In particular, I had been using a configuration that defaulted to native MathML where possible, given that Firefox supports MathML. One sentence in the FAQ caught my eye:

While MathJax’s NativeMML output processor works around various limitations of Firefox/Gecko and Safari/WebKit, the results using the NativeMML output processor may have spacing or other rendering problems that are outside of MathJax’s control.

So I changed the blog configuration to the option now “preferred” by MathJax (“CommonHTML”), but that did not help. Screwing around with the font choices provided by the MathML Font Settings extension, I found exactly one font that displayed correctly. (I forget now which it was, but it was not what I would call an obvious choice.)

I’m not sure what inspired me to try it, but I disabled all three extensions on my desktop machine … and, lo and behold, the problem disappeared. Apparently some change either in MathJax (circa version 2.6?) or Firefox made the font overrides done by the extensions an enemy rather than an ally. I confirmed that disabling the extensions on my laptop also fixed the problem there.

So rendering of math in Firefox is once again working properly … for a while. But I’m leaving those extensions installed, just in case.

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I'm an apostate mathematician, retired from a business school after 33 years of teaching mostly (but not exclusively) quantitative methods courses. My academic interests lie in operations research. I also study Tae Kwon Do a bit on the side.

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