# MathJax rendering bug: wrong interaction between “\tfrac” or “\frac” and “\left[ … \right]”

The code \left[ \dfrac 1 2 \right] displays correctly inline as $\left[ \dfrac 1 2 \right]$ and correctly in display mode as $$\left[ \dfrac 1 2 \right] .$$

The code \left[ \tfrac 1 2 \right] displays incorrectly inline as $\left[ \tfrac 1 2 \right]$ and incorrectly in display mode as $$\left[ \tfrac 1 2 \right] .$$

The code \left[ \frac 1 2 \right] displays incorrectly inline as $\left[ \frac 1 2 \right]$ and correctly in display mode as $$\left[ \frac 1 2 \right] .$$

When I say "incorrectly", I mean that I what see is $\lfloor \dots \rfloor$ ("floor" function brackets) instead of square brackets.

Does this happen only locally, on my computer? Do things render the same for you? Even though I don't like external links, clicking here will display a screen capture of this page as displayed on my computer, hosted under SE account of ImgUr.

• I see square brackets everywhere – Surb Jan 23 '16 at 10:51
• I don't see it. Do you happen to have a high-DPI screen? There was a similar issue with \sqrt, the line was less than 1px high and so wasn't displayed on a high-DPI screen. I guess the same thing happens here. When you zoom in and out does the appearance change? – Najib Idrissi Jan 23 '16 at 10:51
• Try setting the zoom to 99% or 101% and see if that fixes the problem. (Right click, Math Settings, Scale all math) – Asaf Karagila Jan 23 '16 at 10:53
• @NajibIdrissi: I don't have a high-DPI screen. It displays correctly if I zoom in and out at the page level (i.e. using browser commands, not MathJax commands). – Alex M. Jan 23 '16 at 11:05
• @AsafKaragila: 99% and 101% don't solve the problem, but it seems that everything $\le 95 \%$ or $\ge 108 \%$ solves it. – Alex M. Jan 23 '16 at 11:06
• I'm saying, because I had a similar issue once. – Asaf Karagila Jan 23 '16 at 11:17
• @alex M. Could you add a screenshot as well as browser and OS version. Also, the info in MathJax's About panel (via the MathJax menu) would help. – Peter Krautzberger Jan 23 '16 at 11:38
• @PeterKrautzberger: The screenshot is included as a link at the very end of my post. The OS is Windows XP SP3 (with the all the latest patches). The browser is the latest stable Firefox, 43.0.4. – Alex M. Jan 23 '16 at 11:49
• @PeterKrautzberger: About MathJax says: MathJax.js v2.6.0 TeX Input Jax v2.6.0 HTML-CSS Output Jax v2.6.0 PreviewHTML Output Jax v2.6.0 mml Element Jax v2.6.0 AssistiveMML Extension v2.6.0 MathEvents Extension v2.6.0 MathMenu Extension v2.6.0 MathZoom Extension v2.6.0 TeX/AMSmath Extension v2.6.0 TeX/AMSsymbols Extension v2.6.0 TeX/noErrors Extension v2.6.0 TeX/noUndefined Extension v2.6.0 fast-preview Extension v2.6.0 tex2jax Extension v2.6.0 Firefox v43.0 — woff or otf fonts – Alex M. Jan 23 '16 at 11:49
• Thanks for the follow up (and sorry I missed the screenshot earlier). I will try to reproduce it; it might be a duplicate of github.com/mathjax/MathJax/issues/1009. – Peter Krautzberger Jan 23 '16 at 12:41
• You might want to switch to the CommonHTML output in the mean time. – Peter Krautzberger Jan 23 '16 at 12:41
• @Peter: That explains why displayed integral signs looked a bit weird to me recently. – Asaf Karagila Jan 23 '16 at 12:48
• @Asaf try the CommonHTML output. It's faster and shouldn't have the issue. – Peter Krautzberger Jan 23 '16 at 12:51
• @Peter: Not sure about faster (not slower, though, that's for sure), but it did solve that problem. – Asaf Karagila Jan 23 '16 at 13:07
• @PeterKrautzberger, I think it is not issue 1009, but rather this issue and this one, which has been seen several times in the past. – Davide Cervone Jan 23 '16 at 18:24