I've been wondering for a while about the mathematical properties of Flash's built-in easing. I thought it was probably cubic, because a lot of animation programs use cubic splines for their easing. Either that or quadratic.

Turns out Flash has quadratic easing (x^2). Here's a fun science experiment you can try at home. Create a movieclip and tween it on the timeline from _x of 0 to 100, from frames 1 to 11. Put a trace code on the movieclip:

onClipEvent (enterFrame) {
trace(_x);
}

Your output:

1
4
9
16
25
36
49
63.95
80.95
99.95
-----------

x = t*t

=]

~
Robert Penner
Vancouver, Canada
http://www.robertpenner.com
~