specification for easing functions?
Is there a formal specification for what is expected of easing functions?
I see that the linear and swing functions as well as the functions in the easings plugin are written to use a start value and a delta value. But when jQuery core invokes the easing function it always passes a start of 0 and a delta of 1.
What I'm wondering is whether the start and delta values are guaranteed to always be 0 and 1 (at least for jQuery 1.4 and later). If so, it would make easing functions a lot simpler, and Math.sqrt() becomes valid, for example.