Thanks! From your article, you might not want/like my library since it's based on a single easing function. I used a cubic function to find out the interpolation values, and the derivative to make sure it's always smooth. The equation looks like this, it's on the source code:

https://www.wolframalpha.com/input/?i=x+%3D+2+*+t+%5E+3+-+3+...

If you wanted some more details please feel free to ping me (email through my website's resume, or Twitter) and I'll dig the handwritten equations.