Unicode characters in mathed

[Enrico Forestieri]

On Sat, Apr 01, 2023 at 03:09:58PM +0200, Jean-Marc Lasgouttes wrote:
> 
>Hello,
>
>A relative has been using LyX recently, and it is interesting to see 
>how the use is different from what I would do.
>
>In particular, instead of typing \neq in mathed, why not copy and 
>paste a ≠ from some PDF or HTML page?
>
>When doing this, two things happen :
>1/ on screen, there is no spacing around the ≠
>2/ in LaTeX output, the character is exported as \neq and all is well
>
>So how should I solve problem 1/ ? I see 3 solutions
>a/ replace ≠ with a \neq directly in the document at input time; we 
>might not want to do that in case we eventually use unicode in math 
>too
>b/ replace ≠ with a \neq on screen only
>c/ keep the ≠ on screen, but use the mathrel math class from \neq so 
>that we have a good spacing

I would say (a) but only for symbols that are actually translated in 
output.

>Then, I see that there are two ways of matching \neq to U+2260:
>i/ lib/unicodesymbol has a "mathcommand" entry for that (which is 
>presumably used right now)
>ii/ lib/symbols also links these elements
>
>Which one is more reliable for what I want to do?

As I see it, (i) is for export and (ii) is for screen representation, so 
I would suggest using (i).

>My general problem is that, while I see what happens with \neq, I 
>suspect that many weird things can happen with other characters.
>
>Any advice?

Be careful ;)

-- 
Enrico