Re: Multiple underscores crash org latex export; other exporters survive

[Scott Randby <srandby@gmail.com>]

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On 12/07/2016 06:21 AM, Nicolas Goaziou wrote:
> Hello,
> 
> Scott Randby <srandby@gmail.com> writes:
> 
>> On 12/06/2016 06:50 PM, Nicolas Goaziou wrote:
>>> I fixed it in maint. Basically, a_b_c is translated as a\(_b\)\(_c\).
>>
>> With this solution, "a" will be exported as text while "b" and "c" will
>> be exported as a single subsrcipt using the math font.
> 
> Not at all. I simplified the output for clarity but the real generated
> code is
> 
>   a\(_{\text{b}}\)\(_{\text{c}}\)
> 
>> I would prefer that a_b_c be translated as \(a_{b_{c}}\).
> 
> As you pointed out, the string is ambiguous anyway. The point of the fix
> is to generate valid LaTeX code. You can obtain the above unambiguously
> with
> 
>   a_{b_c}

I have a few comments about the choice you've made for the translation
of underscores that do not appear in \(...\) or $...$ expressions. I've
attached a PDF to help explain my points.

First, a_b_c and a_bc give nearly identical results when processed
except that the spacing between letters in the subscript coming from
a_b_c is wider than that in the subscript coming from a_bc. The spacing
issue can be seen more clearly by comparing the processed versions of
a_b_c_d and a_bcd. The wider spacing looks funny when compared to
surrounding text.

Second, I've been considering the issue of what the primary meaning of
a_b_c should be when it is used in a file. Since underscores are used in
LaTeX to designate subscripts in mathematical expressions, it is clear
to me that a_b_c should mean a_(b_c) instead of a_(bc). Similarly, a^b^c
should mean a^(b^c) instead of a^(bc). I really can't think of any case
when I would type in a_b_c in order to get a_(bc).

Finally, I question the use of text style instead of math style when
a_b, a^b, or similar expressions are exported to LaTeX. TeX was designed
to produce beautiful typeset mathematics, and the math style is an
essential part of that beauty. Math style is also the expected way of
presenting mathematical expressions in all of the professional journals
that I read and use. New users may not be aware of professional
standards, but we could help them be aware by translating a_b_c as
\(a_{b_{c}}\) exactly. Similarly a^b^c would be translated as
\(a^{b^{c}}\) exactly.

However, the translation of a_b_c doesn't matter a whole lot to me since
I always use \(a_{b_{c}}\) or $a_{b_{c}}$ in my Org documents.

Scott Randby

> 
> Regards,
> 

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