*Bounty: 50*

*Bounty: 50*

- This question is a follow-up to this question (
*"pgfplots: Strange Bump in*).`tanh`

Function" - Stefan Pinnow, who knows a thing or two about
`pgfplots`

, provided an answer that distinguished between`addplot{tanh(x)};`

and`addplot{tanh(x)};`

(`x`

vs`x`

as the argument). - In a comment, Stefan stated
*"My thought also was that tanh(x) is the same as tanh(x) but it seems that Lua "doesn’t like" "commands", i.e.*".`<something>`

. But to my experience I never used x in addplot calls. Since this is easier to read and easier to type […]`% use TeX as calculation engine addplot {tanh(x)}; % use Lua as calculation engine (when compiled with LuaLaTeX of course) addplot+ [very thick] {tanh(x)};`

- The current
`pgfplots`

manual (Revision 1.18.1 (2021/05/15)) states in Chapter 4.3.3 (Computing Coordinates with Mathematical Expressions):*"In short: it is the same whether you write x or just x inside of math expressions."*.

**Question:**In what circumstances does it matter whether I use`x`

or`x`

in an`addplot`

argument?