Mathf.SmoothStep

static function SmoothStep (from : float, to : float, t : float) : float

Description

Interpolates between min and max and creates smoothing at the limits.

JavaScript
var minimum = 10.0;
var maximum = 20.0;

function Update() {
transform.position = Vector3(Mathf.SmoothStep(minimum, maximum, Time.time), 0, 0);
}