Need guidance on where to start on the study of the variational principle

[Nano-Passion]

I was experimenting with some physics and the mathematics started to get a bit tougher than what I'm used to. I had a professor who looked at what I'm doing, offered to guide me, and told me to do some research on the variational principle.

At the moment, I am in Calculus II. I did a couple searches, and the material I found is well beyond my knowledge at this moment. Can someone help direct me to a proper place to start on this study.

 

[AlephZero]

This looks like a straightforward explanation (well, straightforward in the sense that it
doesn't obscure things with "advanced" notation for no particular reason).
http://www.math.umn.edu/~olver/am_/cvz.pdf

If you don't understand this, first learn what you need from Calc 3 and/or ODEs.

 

[Nano-Passion]

This looks like a straightforward explanation (well, straightforward in the sense that it
doesn't obscure things with "advanced" notation for no particular reason).
http://www.math.umn.edu/~olver/am_/cvz.pdf

If you don't understand this, first learn what you need from Calc 3 and/or ODEs.

Yes there is a bunch of calculus 3 there that I see. Thanks for the link.

 

[Nano-Passion]

Anyone else? I need a supplement.