Editing Differential calculus (section)

==== Calculus of variations ====
{{Main|Calculus of variations}}

One example of an optimization problem is: Find the shortest curve between two points on a surface, assuming that the curve must also lie on the surface. If the surface is a plane, then the shortest curve is a line. But if the surface is, for example, egg-shaped, then the [[Shortest path problem|shortest path]] is not immediately clear. These paths are called [[geodesic]]s, and one of the most fundamental problems in the calculus of variations is finding geodesics. Another example is: Find the smallest area surface filling in a closed curve in space. This surface is called a [[minimal surface]] and it, too, can be found using the calculus of variations.