Symbols: + - * / ^

The usual precedence.

3x == 3 * x

10 sin x == 10 * sin(x)

sin(10x) == sin(10 * x) ... *however*

sin 10x == sin(10) * x

Keywords to try:

Unary operators:

- /x == 1/x
- *x == sgn(x)
- ^x == e^x

BUGS

- doesn't handle off-the-edge cases well (e.g. tan x, when zoomed out)