If it's using the full selection of functions available to KaTeX, here's the list: https://github.com/Khan/KaTeX/wiki/Function-Support-in-KaTeX https://github.

If it's using the full selection of functions available to KaTeX, here's the list: https://github.com/Khan/KaTeX/wiki/Function-Support-in-KaTeX https://github.com/Khan/KaTeX/wiki/Function-Support-in-KaTeX \def isn't included in the core set, from what I can see.