// back easing in
Math.easeInBack = function (t, b, c, d, s) {
	if (s == undefined) s = 1.70158;
	return c*(t/=d)*t*((s+1)*t - s) + b;
};

// back easing out - moving towards target, overshooting it slightly, then reversing and coming back to target
Math.easeOutBack = function (t, b, c, d, s) {
	if (s == undefined) s = 1.70158;
	return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;
};

// back easing in/out - backtracking slightly, then reversing direction and moving to target,
// then overshooting target, reversing, and finally coming back to target
Math.easeInOutBack = function (t, b, c, d, s) {
	if (s == undefined) s = 1.70158; 
	if ((t/=d/2) < 1) return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;
	return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;
};