[luatex] How to get a \mid binary relation that grows in LuaTeX

[Hans Hagen]

On 11/15/2017 6:44 PM, David Carlisle wrote:
> Hans wrote
> 
>> sure but then, using an empty \mathrel{} in there is kind of bad
> 
> It's possibly the only way in classic etex to define a version of
> \middle that gives \mathrel space
> 
> \def\relmiddle#1{\mathrel{}\middle#1\mathrel{}} ... \rmiddle | ...
> 
> acts like a relation with respect to automatic muskips on both sides
> 
> 
>> .. better add some explicit muskip then
> 
> you can't classically detect what \muskip needs adding unfortunately...
> 
> 
> so \Umiddle is (of course:-) a whole lot better (apart from the
> confusing numbering scheme:-) but
> the \mathrel{}\middle|\mathrel{} idiom is likely to be quite common in
> legacy documents moving to luatex
i will have a look at remapping these extended classes (after all we 
don't have more spacing parameters)

Hans

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