I am trying to understand CM wrt QFT and found out that I need to understand the HJE. This brought me to reading about all related subjects. The history lesson alone has been awesome. However, now I am reading about the HJE and found the Wikipedia pages lacking as to exactly what is the nature/idea behind/role of GF's in physics.(adsbygoogle = window.adsbygoogle || []).push({});

[1] GF's in CM

Wikipedia.com says: "Generating functions which arise in Hamiltonian mechanics are quite different from generating functions in mathematics. In the case of physics, generating functions act as a bridge between two sets of canonical variables when performing canonical transformation."

So F(q,P,t) => Q and p can be determined from this F? So F "generates" Q and p??

[2] GF's in E&M:

I recall that there is an equation of motion in E&M which has a delta function as a "generating function" solution.

NOTE: I don't need the physics - I need the _idea_ of what a GF is ... and now that I think about it - are they related???

Thanks in advance.

-LD

__________________

**Physics Forums | Science Articles, Homework Help, Discussion**

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# What is a generating function (GF) in physics?

**Physics Forums | Science Articles, Homework Help, Discussion**