Good question. The epsilon controls the amount of deviation from the path of least action. The delta(x-x0) function makes life easy when it comes to integration. Here is another way to think of it: the purpose of a delta function's life is to be *integrated*. Under the integral sign, the delta(x-x0) forces the argument of an integral to be non-zero for only one value. Hopefully that clears things up.
![The most beautiful equation in math, explained visually [Euler’s Formula]](http://i.ytimg.com/vi/f8CXG7dS-D0/mqdefault.jpg)
Ahhh , what a video. Refreshing and fun to see these advanced concepts
Thank you Refath
I am big fan of your family
I want to learn more math and physics.
Very very nice
When light will pass from air to glass, will deviate towards the normal,not away from it
Veryy amazing ❤
Love from India
Why it is written epsilon* delta(x-x0) for the small deviation of epislon?
Good question. The epsilon controls the amount of deviation from the path of least action. The delta(x-x0) function makes life easy when it comes to integration. Here is another way to think of it: the purpose of a delta function's life is to be *integrated*. Under the integral sign, the delta(x-x0) forces the argument of an integral to be non-zero for only one value. Hopefully that clears things up.