[texhax] Adjusting parentheses for intervals and functions

[Morten Høgholm]

On Mon, 23 Aug 2004 10:55:39 +0000 (GMT), <Ian.Collier at comlab.ox.ac.uk>  
wrote:

> Forgive me for asking, but what /is/ the difference between "virgule"
> and "solidus"?  Which TeX chars are we talking about?

The solidus and virgule are different characters, no question about it.

The virgule is primarily used for level fractions such as $2\pi/3$ or in  
running text as "he/she threw an apple at the doctor to keep him away". It  
can also be used as an alternative to comma in Herlev / Denmark / Earth or  
in dates 2004/08/23.

The solidus slopes much more (typically close to 45 degrees) and is used  
for split level fractions as "He took 7/8 of the pie."

> The TeXbook doesn't seem to make any distinction between those words,
> and neither does my dictionary.  (It all sounds a bit like a case of
> "ocean grey vs military grey"...)

The TeXbook not mentioning them is connected to the fact that Knuth didn't  
incorporate the solidus or ready-made fractions like 1/2 (you know the  
character, but I'll stick to ascii here). The fractions and solidus in the  
EC fonts have a somewhat unusual design, which didn't help matters much,  
if at all. The Latin Modern fonts on the other hand show a clear  
distinction between the solidus and virgule, as does almost any other font  
I can think of.

The documentation of the xfrac package (okay, I'll stop advertising ;-)  
contains a brief discussion of this topic.

The example file below shows how the solidus and virgule look in various  
fonts. The character width of the Latin Modern solidus will hopefully be  
fixed in an upcoming release (the authors have been notified).

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{textcomp}
\newcommand*\sample[2]{%
   \fontfamily{#2}\selectfont
   #1:
   \textonehalf, solidus: \textonesuperior\textfractionsolidus
   {\footnotesize a} virgule: a/b
}
\begin{document}
\sample{Computer Modern (EC)}{cmr}

\sample{Palatino}{ppl}

\sample{Times}{ptm}

\sample{Latin Modern}{lmr}
\end{document}
-- 
Morten Høgholm