public override void update (float t)
{
float newT = 0;
if (FloatUtils.EQ(t , 0) || FloatUtils.EQ( t , 1))
newT = t;
else {
float s = _period / 4;
t = t - 1;
newT = -Mathf.Pow(2, 10 * t) * Mathf.Sin( (t-s) *(Mathf.PI * 2) / _period);
}
_inner.update(newT);
}