# Eikonal equation

1. Oct 17, 2007

### Asuralm

Dear all:

I have met a equation called Eikonal equation which is a special case of Hamilton-Jacobi equation. It is writen as:

||$$\nabla$$f(x)|| = P(x)

Could anybody explain what's the meaning of this function please? I have read it from Wiki and mathworld, but it doesn't make too much sense to me.