Add the second section in the post of Laplacian approximation
Add the second section in the post of Laplacian approximation

In this time, I have added the description of the application of the
Laplacian approximation.

Gwan-Siu/gwansiu.github.io,Gwan-Siu/gwansiu.github.io,Gwan-Siu/gwansiu.github.io