Fermat principle的用法和樣例：
例句
- Fermat's principle is not so much a computational device as it is a concise way of thinking about the propagation of light.
費馬原理更多的是對光的傳播的一種簡明看法，而不是一種計算工具。 - The paper is to prove the refraction on two kinds of medium interfaces of electric displacement line using the boundary condition of the electric field and Fermat Principle.
利用電場邊界條件和費馬原理證明電位移線在兩種介質界面上的折射。
