This is a pen project I created using lines and a tad bit of basic calculus equations (namely f(x)=dx+epsilon). I had the derivative calculated (rate of change) and the integration (area of each point) calculated. It then calculates the area from point of x -70 to x -60 )the shaded bit)! (Measured in d/1th of an x.)
This was me and a book called SCIENCIA that explains calculus in a page (no, you don't need an entire year of it).
