Someone else pointed out Bézier curves. What is interesting is such are same as the bending equation! Back in the pre-cad days, designers would bend a piece of

Someone else pointed out Bézier curves. What is interesting is such are same as the bending equation! Back in the pre-cad days, designers would bend a piece of thin, elastic spline-wood to draw curves. From the side it looks exactly like a Bézier curve, this is not a coincidence, Beziers are more or less same as the physical bending equation for such a spline.