Make MC shiver?

1

Hi guys,
Math not being one of my strong points the fla’s i came across hurt my head lol.

What i want to do is basiclly make an Mc shiver for 3-4 seconds.

What i have so far is this on the mc


onClipEvent (load) {
 this.elasticEffect = function (tar, accel, convert) {
  xPos = xPos * accel + (tar - this._x) * convert;
  yPos = yPos * accel + (tar - this._y) * convert;
  this._x += xPos;
  this._y += yPos;
 };
}

and then


win.elasticEffect (220, 0.7, 0.4);

But this only moves it to postion of 220.

Can some help

thanks