This program displays a surface z = f(x,y) together with its tangent plane at a movable point. The tangent plane is spanned by the partial derivative vectors (1,0,f_x) and (0,1,f_y) and represents the best linear approximation to the surface at that point. The math.js library computes the partial derivatives numerically, and the tangent plane updates in real time as the point is moved.
Controls: Click and drag to orbit, scroll to zoom.
