TeX question...

[Qubit]

OK, this may not be the right place to ask, but if I ask it on the TeX newsgroup, they'll blow my head off:

How can I make the 'd' of a differential look non-italic? If I type something like
'\frac{ dx }{ dy }' in math-mode, all the d's are italic, but in math books they are non-italic.

[Strike]

use \frac{\textrm{dx}}{\textrm{dy}}

There may be a better way to do this, but when I need to do things like this just once or twice, like if I use the hyperbolic transcendental functions (case in point, tanh), I just throw a font modifier around it.

[Qubit]

Thanks, Strike, that looks exactly how I wanted it.

BTW: aren't there any macro's for the common functions like tanh? (maybe \exp )