I didn't even think it would even be an issue, so I didn't post earlier, but…
The escape sequence should be $
.
$
is what people who already know (La)TeX use. Even more importantly, $
is what people who already know how to write math on Stack Exchange use — it's what Mathematics SE uses, and it's what all the MathJax documentation on Stack Exchange (mostly on Math meta) uses. Even the upstream MathJax documentation uses $
in its examples (even though the MathJax preprocessor doesn't have $
active by default — it has \(…\)
instead).
Using \$
reduces the discoverability of MathJax. If I suspect that MathJax is enabled but am not sure, I'll type $a$
— see that it doesn't come out as math, so no, there's no MathJax.
It's to be expected that we'll have migrations between Puzzling and Math at some point. Ok, that only concerns a small number of questions, but it would be a gratuitous incompatibility. Still, it's the human dissonance that I'm mostly concerned about, far more than the technical dissonance.
In all the posts I've seen during the beta where people assumed that we'd have MathJax, they used $
. I didn't see a single post with \$
. When MathJax was announced, people even started to edit posts to use $
— because for a few hours, $
was what we had. Changing to \$
midstream means even more work.
And what's the point of using \$
? To avoid a relatively rare case where two dollar amounts are used in the same paragraph. People already run into trouble when they use an unprotected _
or *
and feel safe, and then use a second one and get italics all of a sudden. $
would be no worse than that. It's very visible in the preview, too.
I could see the point of picking \$
if there were already many posts using $
(which, as far as I reason why EE.SE uses \$
— because it was enabled only after the site had been existing for a few months and the attempt to use $
broke quite a few existing posts). By exactly the same argument — breaking existing posts — this site should use $
.
\$
for inline and$$
for standalone math. $\endgroup$ – SQB May 23 '14 at 6:41