Calculus of variations

Calculus of variations is a way of solving problems about things that can change, or vary. It looks for a way to make something bigger or smaller, depending on how you want it to change. Let's say you have a wiggly line. Calculus of variations helps you to find the wiggliest line of all. To do this, you have to figure out the line that gets the biggest or the smallest when it changes. That's what calculus of variations is all about.