The single-letter variable names and the lack of types (beyond some duck-typing using bold and uppercase) is what makes math so difficult to read (for me). There must be tons of errors in math papers that go undetected just because there’s no type checking.
Also, any halfway decent math writers (including those writing for domains that use math, but are not strictly done by mathematicians) also define their terms or provide a context. If you're doing physics, the following is perfectly comprehensible (and is useless if you haven't studied at least a bit of physics):
x(t) = x_0 + v_0 * t + 1/2 * a * t^2
In a physics book, all of those terms would have been defined prior to that statement, but you wouldn't exclude that equation because it's so useful later on (to actually do calculations with, or to solve for the other elements).
If you take any arbitrary APL program or mathematical statement out of context, it's going to be mostly meaningless. I mean, I can tell you what that does above if I've taken algebra but haven't taken the first couple weeks of Physics 101, but I don't know what it means so it's not useful. That's not the fault of the equation and it shouldn't be discarded just because it needs context to fully understand (either context fully stated with it, or an expectation that you've already studied the topic and so a minimal context can be provided and you can fill in the gaps).
