jQuery easing function — variables' comprehension

Question

How does the easing function for jQuery work? Take for example:

easeInQuad = function (x, t, b, c, d) {
    return c*(t/=d)*t + b;
};

How d

Answer 1

t: current time, b: start value, c: change from the start value to the end value, d: duration.

Here is how it works: http://james.padolsey.com/demos/jquery/easing/ (curve representing when a CSS property is changed).

Here is how I would implement some dumb easing: http://www.timotheegroleau.com/Flash/experiments/easing_function_generator.htm (math is not my strong suit)

You would extend like any of these: http://code.google.com/p/vanitytools/source/browse/trunk/website/js/custom_easing.js?spec=svn29&r=29 - good enough!