Expression Manipulator v0.5 (bugs fixed, derivatives completed)

Basically, this program takes some mathematical expression you type in, parses it, and deals with it in different ways. (Like taking the derivative, or combining like terms, etc...)

See included 'Documentation' file for instructions for use. It's just source code, but I'll attach an executable soon, maybe in the morning, maybe earlier.

Derivatives should be completed. If you see a hole, let me know so I can patch it. I added some fairly obvious functions: add(), sub(), mult(), div()

expt(x,y,z,...) = x ^ (y * z * ...)

exp(x) = e^x where e is the constant

Multivariable functions have been added. add(3) is as valid as add(3,4,5)

Any questions? Comments? Things you want added?