# The double-bar delimiter does not stretch in MathJax 2.2

With the recent switch to MathJax 2.2, it seems that the double-bar delimiter (i.e. \|, or \lVert and \rVert) does not stretch when used with \left and \right (on my computer at least). The problem doesn't appear to occur with any other delimiter.

Consider the code

$$\begin{array}{cc} \| \frac{a}{b} \| & \left\| \frac{a}{b} \right\|\\ \{ \frac{a}{b} \} & \left\{ \frac{a}{b} \right\} \end{array}$$


Here it is as rendered by the site (this is not a screenshot): $$\begin{array}{cc} \| \frac{a}{b} \| & \left\| \frac{a}{b} \right\|\\ \{ \frac{a}{b} \} & \left\{ \frac{a}{b} \right\} \end{array}$$ Here it is as I see it in Chrome 26.0.1410.64 m (zoomed in 150%):

Here it is as I see it in Internet Explorer 10.0.9200.16540 (zoomed in 150%):

I'm using Windows 7 Home Premium 64-bit. For both Chrome and IE, I have cleared the cache and restarted the browser.

• I see it just fine, as rendered by the site. (FF-21.0/Arch Linux 64bit)
– Asaf Karagila Mod
May 20, 2013 at 5:45
• I see the same bug (double bars are not resized) in current Chrome, FF, IE, and Opera (Windows Vista ... unfortunately). May 20, 2013 at 6:26
• I see the bug in Safari 6.0.4 and in Firefox 20.0 under Mac OS 10.8.3. May 20, 2013 at 8:35
• I see the same bug. About MathJax says "MathJax v2.2 using web TeX fonts". With one browser it also says: "Firefox v16.0 — woff or otf fonts"; with another: "Safari v5.1 — woff or otf fonts". I just checked; this does not appear under MathJax v2.1, so this appears to be a MathJax v2.2 bug. I will report this on the bug tracker.
– robjohn Mod
May 20, 2013 at 11:59
• The issue also appears for me, using local STIX fonts on current Chrome, Win 7. So it appears to be a coding error rather than some rendering glitch. May 20, 2013 at 12:22
• I see the bug in Chrome 26.0.1410.63 and Firefox 20.0 using Fedora 18. May 20, 2013 at 16:55

Good catch Zev! This does not appear under MathJax v2.1, so this is a MathJax v2.2 bug. It is now listed on the GitHub bug tracker.

• There was a change in how \left...\right is handled in v2.2, and there is a bug with some delimiters. It will be fixed in the next release. I could provide the powers that be with a patch to use in the meantime, if they are interested. May 20, 2013 at 22:33
• @Davide: Is there an estimate on the next release? (I know there is no release cycle to MathJax like there is to the linux kernel, but the answer as to whether or not a temporary fix is needed may very well depend on the current estimate whether or not it's a week or a month or six.)
– Asaf Karagila Mod
May 21, 2013 at 0:16
• We are hoping to do another release relatively soon (on the order of a month or so). This is intended to address some font issues, and most of the work is already done. We are also discussing whether this should be a hot-fox on the v2.2-latest branch, which would mean it could go out very quickly. May 21, 2013 at 10:24
• The fix has been made as a hot-fix for the MathJax CDN, so you should see the correct behavior now. May 25, 2013 at 22:23
• @DavideCervone: It looks good to me on all three delimiters I've seen a problem with. Thanks!
– robjohn Mod
May 25, 2013 at 23:41