Re: spurious space after macro expansion in math mode for TeX output

[Vincent Lefevre]

On 2022-11-08 23:07:51 +0100, Vincent Lefevre wrote:
> ------------------------------------------------------------
> \input texinfo    @c -*-texinfo-*-
> 
> @tex
> \gdef\texatan{\mathop{\rm atan}}
> @end tex
> 
> @iftex
> @macro atan
> \\mathop{\\rm atan}
> @end macro
> @end iftex
> 
> Spacing test with atan.
> 
> @math{\mathop{\rm atan}(x)}
> 
> @math{\texatan(x)}
> 
> @math{@atan{}(x)}
> 
> @bye
> ------------------------------------------------------------
> 
> I get:
> 
> Spacing test with atan.
> atan(x)
> atan(x)
> atan (x)
> 
> So, one gets the expected behavior with the TeX macro (no space added).
> But with the Texinfo macro, a space is added. This is unexpected: one
> should have got the same behavior as with the Tex macro. This means
> that Texinfo is adding something else in its macro expansion.

Actually in the PDF rendering, that's

Spacing test with atan.
atan(x)
atan(x)
 atan (x)

i.e. the Texinfo macro generates a space both before and after "atan".
But pdftotext shows a space only after "atan" (perhaps because this is
based on a heuristic).

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)