mathjax
Math in vertical writing mode
Modern browsers have recently implemented vertical writing modes. The vertical writing modes are not only useful for CJK text but also for European languages. Authors sometimes want to rotate text by 90 degrees due to space constraint (especially on printed pages) or for design purpose. Please see this article for some of such examples. Especially we often want to layout tables rotated by 90 degrees when the table is wider than the page width.
I tried using MathJax with vertical writing mode (JS Bin), but layout of MathJax seems not to be working well. Is there any plan to support math in vertical writing mode?
We have no immediate plans to support this use case, but I'm marking this a feature request so that it can be considered in the future.
MathJax uses top/bottom/left/right spacing, padding, and so on, in many places, and it appears that these properties retain their original orientations even in vertical direction modes, so support for this would require MathJax to switch all the top to rightstyle (for your example), and similarly for all the other sides. While it might be technically possible to do this, support for both horizontal and vertical directions would require considerable complication to an already complex process.
The best hope might be to use SVG output, and impose a rotation on the results while swapping the height/depth of the bounding box. It might be possible to use the "New Math" signal to implement a post-filter that handles the details.
FYI, there is CSS Logical Properties and Values spec, in which properties and values specifying logical directions (block-start/block-end/inline-start/inline-end) are defined. Those directions correspond to different physical directions depending on writing mode, so they could be used to specify layout in the writing-mode-agnostic manner. Unfortunately, though, implementation of those logical properties/values by browsers is limited at this moment, so you might need some kind of polyfill in the short term.
OK, thanks for the additional information. That is good to know, and it does look like that might make thing easier to handle, once they are implemented widely enough.