Even worse than trying to search for single-letter variables that are defined somewhere in a mathematical text is trying to find the definitions of operators, if all you know is the squiggle used to denote that operator. For example, integrals are denoted by a slide-looking squiggle, so if you see one and don't know it's called an "integral", you can't look up what it means. If you do find a definition, the Wikipedia page you'll get describes integrals as "the signed area of region bound by (the function parameter's) graph", with a full-page of explanation and links to 5 or 6 pages of supplementary explanation. Good luck translating that into code!

What you won't find is the 5-line program that shows you how to actually calculate an integral (for that, see this page from SICP). Mathematicians descend into maddening vaguery when trying to describe concepts that could easily be described by a very short computer program, because math notation (and therefore mathematical study itself) lacks an equivalent of the for loop. So instead, mathematicians think they're describing something so fundamental that it's ineffable-- Integrals, man! Integrals! Either you grok it, or you don't.