I'm needing some kind of line or line~ but using other equations, like quadratic or qubic.
I attach an image of Robert Penner's equations. These equations was made for ActionScript to use in Flash... but, they are under BSD license. I ported easeInQuad, easeOutQuad and easeInOutQuad equations to Python. Someone ported them to Rhino, too... Maybe they can be ported to Pd.
Here is the Tweening chapter of his book: http://www.robertpenner.com/easing/penner_chapter7_tweening.pdf (from his page)
... or maybe they are already done in Pd... are they?