Well, for the most part, LaTeX only provides common operators. One problem, I came across some weeks ago, is that it is *not* possible to define his/her own operators (or, at least, that Lamport's "LaTeX - A Document Preparation System" doesn't tell you how you can define them).
It's actually fairly easy. There are several ways to do it. A simple hacky way to do it is the following: * Draw a little picture of your operator in your favorite drawing package. * Save this picture as an EPS drawing * define a new command that inserts this eps drawing, possibly scaling it appropriately. E.g. \newcommand{\myop}{\scalebox{0.1}{operators/myop.eps}} * Then just use \myop like any other operator in math mode. What this hack won't do is automatically change the size of the operator if the maths is in a subscript. There is probably an easy way to do this, but I haven't worked it out. A more elegant way to do it is to define a new postscript font (not hard if you have the correct software) and then define your operator macro to insert the relevant character. Hope this is useful to someone. -Rob