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I regularly use MSE on a mobile device, as that is when I have the time spare to visit.

Since upgrading to iOS 6, instead of MathJax displaying correctly, I get a "Math Processing Error" in the place of only some math. In other places, it displays properly.

Here is a picture of a typical page, which is a screen shot of this page.

Are other people having the same issue?

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  • $\begingroup$ A link to the offending expression and/or a screen capture would be helpful. $\endgroup$ – Bill Dubuque Oct 4 '12 at 22:32
  • $\begingroup$ I'm having the same issue. $\endgroup$ – Qiaochu Yuan Oct 4 '12 at 22:34
  • $\begingroup$ I had that a few times, but iOS 6 gives me quite some trouble anyway... $\endgroup$ – Asaf Karagila Oct 4 '12 at 22:39
  • $\begingroup$ Works fine on Android 2.3.5 and 4.0.4, so may be iOS specific. $\endgroup$ – Bill Dubuque Oct 5 '12 at 0:01
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Math.SE moved to the beta version of MathJax v2.1 on Monday. Did you upgrade to iOS6 around then? It turns out that there was a line-breaking problem in MathJax v2.1 (see this post), and the lines that are giving you the processing errors are the ones that would need to be wrapped for your device, so I suspect it is that problem. A bug fix was made available yesterday morning around 9:00AM Eastern time, but you might need to clear your cache and/or restart the browser in order to get the updated version.

In iOS you can clear the cache through the system preferences app, in the Safari preferences (I don't remember exactly where). You can restart the browser by double-clicking the home button on the device: you will get a line of all the running application at the bottom of the screen; click and hold one of them to start them jiggling, then click the minus sign at the upper left of the Safari app to stop it.

If you still experience problems after clearing the cache and restarting the browser, let me know.

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  • $\begingroup$ I am not using Safari, but Dolphin. I also wish to avoid cache clearing, because I have quite a few cookies I wish saved. Can you give a specific site that we should clear from the cache for that? (I also upgraded to iOS 6 when it was released some time ago, but I don't recall this happening before, but that doesn't mean much...) $\endgroup$ – Asaf Karagila Oct 5 '12 at 16:05
  • $\begingroup$ I updated around then, yes. I clear the cache regularly and restart safari often. I have even tried this in conjunction with a device restart. The page I linked to above still displays errors. $\endgroup$ – Daryl Oct 5 '12 at 20:56
  • $\begingroup$ @AsafKaragila, I don't use Dolphin, so I don't know what its settings are like, but I would expect you to be able to clear the cache without clearing cookies (at least Safari allows that). The MathJax CDN at cdn.mathjax.org is the site that needs to be cleared. The files will eventually get stale and need to be refreshed (I don't know what the expiration is for the beta, but it might only be 24 hours). I really think it will work if you get the updated version of the line-breaking code. $\endgroup$ – Davide Cervone Oct 5 '12 at 23:32
  • $\begingroup$ @daryl, I have just checked with an older iOS (the device doesn't support iOS6, and I don't have another one handy that I can upgrade). It works for me, and the symptoms really look like the line-breaking problem that was recently fixed. So I'm wondering if the cache clearing really worked. I'll see if I can find an iOS6 device to test with. $\endgroup$ – Davide Cervone Oct 5 '12 at 23:34
  • $\begingroup$ Oh, I have some rough memories from Safari clearing away too much when just clearing data. I believe that the underlying engine of Dolphin and Safari is the same, by the way. I also cannot reproduce the bug consistently, it just happens every now and then. $\endgroup$ – Asaf Karagila Oct 5 '12 at 23:36
  • $\begingroup$ @AsafKaragila, When you have the problem, is it only long equations that give errors, or all equations? If you determine anything that seems to be common about the times you get the problem, let me know. Yes, Dolphin uses WebKit as I recall. $\endgroup$ – Davide Cervone Oct 5 '12 at 23:38
  • $\begingroup$ I am not using my iPhone a lot in the past two days, so it's hard to tell. I think it was not restricted to long equations, but others might be able to shed some light on this. In the meantime I have cleared the cache of the Dolphin. I'll try to test a few pages with long equations and see how it goes. $\endgroup$ – Asaf Karagila Oct 5 '12 at 23:41
  • $\begingroup$ Update: I have tried the link in the question (after clearing cache in the Dolphin, of course) and it works. However I do not recall checking that page myself before so I don't have a good controlled environment here. I will give it some time to run between the pages during peak hours tomorrow and we'll see how well it runs. $\endgroup$ – Asaf Karagila Oct 5 '12 at 23:44
  • $\begingroup$ @DavideCervone It worked on iOS5, but stopped when I upgraded. This new iOS has been quite frustrating... $\endgroup$ – Daryl Oct 5 '12 at 23:46
  • $\begingroup$ It happened just now on math.stackexchange.com/questions/208109/… $\endgroup$ – Asaf Karagila Oct 6 '12 at 9:08
  • $\begingroup$ When I hit the refresh button it worked again. I am guessing this is just some buffering issue which is borderline failing and when it does a refresh usually solves things up. $\endgroup$ – Asaf Karagila Oct 6 '12 at 9:35
  • $\begingroup$ @AsafKaragila, If one of MathJax's files takes too long to load, MathJax will time out and try to go on without it. If that file happens to be something like the HTML-CSS output renderer, then you will get the processing error for every math expression. Reloading can often resolve this, as the file may arrive earlier. Mobile devices with slower connections tend to be particularly susceptible to these timing issues. $\endgroup$ – Davide Cervone Oct 6 '12 at 11:23
  • $\begingroup$ The update just made it to Australia. Problem fixed. $\endgroup$ – Daryl Oct 7 '12 at 20:13
  • $\begingroup$ OK, glad it is working for you know. Thanks for the additional information. $\endgroup$ – Davide Cervone Oct 7 '12 at 21:02

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