* Area between curves
This is a nifty little program to enhance the computational ability of
your TI83 family calculator. I'm not sure about you, but my calculus
teacher told me there was no way for my calculator to calculate the
area between curves at the touch of a button. Well, these TI89's are
off the chain but I've come up a with a nice little patch that lets
our little beaut's perform just the same.

** Entering equations
If both Y1 and Y2 are populated, curves will choose those two
equations and find the area between them. If one or more are blank,
you will be prompted for both.

*** Change your mind?
Press `Y=' during calculations to change the equations, or `TRACE'
(window) to change the domain in which intersections are calculated.

** Caveats
I wasn't in class long enough to make this program sophisticated
enough to comprehend vertical bounds, or know how to react if only one
equation was within range of the window. This program will function
just fine if you can see everything of interest on the graph, so just
use those settings and let this do its magic.

** Output
After calculation, the totaled area will be shaded, the final answer
stored to Ans, and a message will be printed on the screen.
