A function of two inputs gives a height above every point in a plane. Rotate the view to see the shape.
The mesh samples a real-valued function at a grid of input coordinates. Rotation changes only your viewpoint. The selected point’s coordinates and height always come from the same function.
Screen height depends on perspective; the displayed z value is the actual mathematical height.
Drag to rotate, or use the view sliders. The surface and level curve are sampled; all point values and derivatives use exact formulas.