# Undefined control sequence \pu in official SE Android app

For some reason content produced with \pu{} cannot be rendered properly in official Stack Exchange android app, though \ce{} renders perfectly fine. For the reference, this is a screenshot from Samsung i9100:

It seems like this problem persists at least since November 2016. Is there a workaround?

• Same issue: MathJax in the Android App. (Didn't close as duplicate since you specifically asked for a workaround) – orthocresol Jul 1 '17 at 3:58
• @orthocresol Thank you! I missed that post entirely, my bad. I'm curious, is there a fallback-mode that can be enabled to see at least the source code on a smartphone? – andselisk Jul 1 '17 at 4:02
• It's ok - no problem. There isn't a fallback that I know of, although you might want to ask on Meta Stack Exchange. – orthocresol Jul 1 '17 at 4:03
• @orthocresol Well, I'm going to stick with web browser then, and use an app to receive notifications only. Thanks a lot for a quick answer! – andselisk Jul 1 '17 at 4:05
• The notion that \ce{...} renders perfectly fine is not quite correct. The app uses an old version of MathJax, and even that command has gotten some changes. While it still renders, it might look different in the app than in the browser. – Martin - マーチン Jul 1 '17 at 8:31
• @Martin-マーチン mhchem result does look somewhat more edgy in the app comparing to web version, but it doesn't bother me at all. Though missing content surrounded by \pu{} does. So would you suggest to continue using pu{} and hope that at some point the devs responsible for Android app will sort it out? – andselisk Jul 1 '17 at 8:38
• I understand that and I am annoyed by that, too. I don't think there will be a fix for it any time soon. The MathJax in the app problem has been around now for a couple of years, it's just that it will get worse with any new version of MathJax being deployed. Until they finally decide to scrap the app. I recommend using the browser to browse and read questions. – Martin - マーチン Jul 1 '17 at 8:42

The workaround is to go back to using \mathrm:

$2.01~\mathrm{g}$ $2.01~\mathrm{g}$

$450~\mathrm{kJ~mol^{-1}}$ $450~\mathrm{kJ~mol^{-1}}$

But apart from that I don't think there is anything we can really do on our end.

• I would not recommend using any kind of workaround, but stick with the most recent version of MathJax. I especially would discourage anyone from removing \pu{...} commands. I can't find the corresponding meta.se discussion now, but the traffic coming in through the app is so small compared to any of the browsers, that there is little hope they will fix the app. It is more likely they will just discontinue it altogether. If that happens we'd have done a lot of editing, that is essentially obsolete. – Martin - マーチン Jul 1 '17 at 8:29
• $\pu{314159265 M}$ gives a nice spacing between every third digit ($\pu{314159265 M}$), which is absent in $314159265~\mathrm{M}$ ($314159265~\mathrm{M}$). Any way to work around that other than manually inserting spaces $314~159~265~\mathrm{M}$ – Gaurang Tandon Jun 13 '18 at 17:24
• @GaurangTandon I don't know why I didn't see this comment, but: "Where separation of numbers into groups of three digits is used, the groups shall be separated by a thin space \, (backslash comma); e.g. $299\,792\,458$ yields $299\,792\,458$." chemistry.meta.stackexchange.com/a/88/16683 – orthocresol Aug 27 '18 at 10:40