DOC,BLD: Switch to `xelatex` engine for latex docs?

When building the latex/pdf version of the documentation, sphinx is currently configured to use pdflatex (the default) to build the pdfs of the user/reference manuals. There are several places in the documentation where the use of unicode characters causes inputenc warnings when building the pdf. In some cases these can be resolved by ensuring that extra latex packages are installed (e.g. texlive-langgreek adds the necessary mappings for some Greek Unicode characters), but in other cases (e.g. U+22EE vertical dots) it is more difficult to find an appropriate package (or the mapping can be done manually via \DeclareUnicodeCharacter).

In addition, there seem to be some URL ref problems that are avoided by xelatex (see sphinx-doc/sphinx#7723).

Please share any thoughts and possible pros/cons of switching to xelatex for the NumPy latex/pdf docs. Note that sphinx provides a latex_engine configuration option that makes this simple to try.

[melissawm]

Oh, then if it’s irrelevant I’d say we go for it. xelatex is available in every major LaTeX distribution on whatever OS, and it does make everything easier with respect to unicode and font issues.

[rossbar]

I like xelatex personally, but it can be much slower than pdflatex. Could that impact the docs build time significantly or is that irrelevant here?

Great point - I did some quick profiling to get an idea of the build times. The results of time make -C build/latex on my system

with pdflatex:

real    0m43.972s                                                               
user    0m43.154s                                                               
sys     0m0.552s

with xelatex:

real    1m13.522s                                                               
user    1m19.858s                                                               
sys     0m2.205s

So xelatex is definitely slower, but the total build time still isn’t so bad, especially since I don’t think building the latex docs from source is very common for most users. Note that in each case, the latex->pdf step is still shorter than the initial rST->latex step (~2m30s on my system).