// t: time (current time or time difference)
// b: begin position
// c: change in position 
// d: duratino (in msecs)
// a: amplitude (can be empty)
// p: period (can be empty)

Tween.elasticEaseOut = function (t,b,c,d,a,p){
		if (t==0) return b;  if ((t/=d)==1) return b+c;  if (!p) p=d*.3;
		if (!a || a < Math.abs(c)) { a=c; var s=p/4; }
		else var s = p/(2*Math.PI) * Math.asin (c/a);
		return (a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b);
}