Is there any chance that we could add those two fonts to MO?

It seems like all you would have to do is add the following to the preamble of jsMath:
\usepackage{mathrsfs}
\usepackage{eucal}

This allows us to use any of the three calligraphic fonts by typing in

\CMcal{-} (CMcal - standard)
\mathscr{-} (rsfs)
\mathcal{-} (eucal)

Edit: I looked over the source for eucal.sty again and realized we can just leave eucal as it was (because the .sty defines CMcal).

Why don't you just call eusm10 "\eucal" and put a note in the FAQ? I mean, when I think of the font, I think of the package name.

If you'd really prefer it as "\cal", could you set both "\eucal" and "\cal" to eusm10?

I'm pretty sure that jsMath does not load the files unless they are used on the page. Anyway, you can just download the proper fonts and not worry about it =p.

If I'm answering a question on MO it's typically a number theory question and I find myself having to write "\mathbf{Q}" 6-7 times. This actually put me off once to the extent that I just typed a plain text answer, writing Q_p instead of $\mathbf{Q}_p$ on the basis that anyone reading would know exactly what Q_p meant and who cares if it didn't look as good---indeed, if some did care they could just edit the post themselves :-)

My point then is that another solution would be to define some standard macros: \bfQ for \mathbf{Q}, \calC for \mathcal{C} etc etc, that all users could use. Would this be a solution to fpqc's underlying problem which would make Andrew happier? I have seen TeX files by other people which start with "\def\bfA{\mathbf{A}}\def\bfB{\mathbf{B}}...\def\bfZ{\mathbf{Z}}\def\calA{\mathcal{A}}..."even if most of the defs aren't used in the paper.

Kevin, the abbreviations aren't the problem, it's the extra junk that has to be sent over the wire in order to display it.

(Really, all the conversion should be done server-side but that's not possible with the current software so I'm not going to shout about that. I only mention it now because I've been hacking together some MathML-generation scripts and it's on my mind.)

(Oh, and I loathe tex files that start like that. At the very least, they ought to use a loop command to define all the commands in one go.)

Anton, I'll see what I can do when I get back to Norway. I'm currently in Brazil on an extremely buggy and slow connection via a hotel wireless network (at least, I hope it's the hotel's network. If next time I answer a question then I appear to be in the Antarctic then you'll know that it wasn't the hotel's network and someone's stolen my id) so these issues are even more important!

Being away from my desk and trying to do mathematics over slow connections and via non-university subscribers has reminded me that places like MO have extra value because they are completely open. The only bar to joining in is understanding the mathematics: there's no subscription or limitation on who can ask or answer. Let's not get rid of that by putting in loads of stuff to download which is fine for those in the US with super-duper connections, but makes it next to impossible to use for those with more shaky infrastructure.

I suppose I ought to download those fonts (darn it, I've already got the STIX fonts, what more does jsMath want from me?). However, I'll need to figure out if it can be done in such a way that clearing my cache doesn't get rid of them (anyone know? And, no, I'm not going to turn off that feature.).

However, you can be pretty sure that I'm going to stick around MO for a while even if jsMath proves such a pain. But it's not me that you should be worrying about: it's the ones who come for the first time, find that it takes half an hour (yeah, yeah) to load even the first page, and go away again.

@Anton,

it appears that we already had rsfs10 in latex.mathoverflow.net/jsMath/fonts/, but not eusm10. I've fixed that now. I haven't done anything about macros. I think you should now have sufficient privileges in the latex.mathoverflow.net/ hierarchy.

I don't believe either of those statements either. (There's a sentence with two "either"s which hopefully mitigates the appalling sentence I just posted containing two "actually"s.)

I would like to point out a danger of having two calligraphic fonts available. That is, that while it is unlikely that one person will use both, there is usually more than one person involved in what's on a page. So all it takes is for one person to use one font and another to use the other and you've got both being downloaded.

(Incidentally, when the fonts download, do they download the whole font set or just the characters being used?)

You can download the opentype or truetype fonts directly to your computer, in which case, it is not an issue!

Yes, I know that I can do that. But only die-hards like those that frequent these metaphoric meeting halls are going to both know that they can do that and be bothered to do it. I'm concerned about those who encounter MO for the first time, possibly over a slow connection, and find that it takes a loooooonnnnnnggggggg time to see anything.

We should aspire to make the site as fast as possible for everyone.

Even if speed were not an issue, it would pain me to see somebody asking a question using eucal and somebody else responding with mathcal. I still can't come up with any good reason to support multiple calligraphic fonts.

Not cleanly. cmsy10 is loaded by default (as are a bunch of cm fonts). I could load eusm10 and redefine \mathcal and \cal, which is pretty crufty. It would also be annoying for people who actually went to the trouble to install the TeX-fonts to get faster pages or cleaner type, because cmsy10 (which contains CMcal) is included in the TeX fonts but eusm10 is not.

What's wrong with CMcal?

You should be able to do this client-side. I've no real idea how to do it, but if you've downloaded the fonts you ought to be able to muck around with them to your heart's content.

What I meant was that fpqc should be able to redefine stuff so that firefox serves up eucal instead of CMcal just for him without disturbing the rest of us.

"Client-side" means "Anton doesn't do anything".