Talk:Euler-Lagrange equation

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I'd appreciate feedback on this proof. Is it too long? Too technical? Not technical enough? A simple proof is very appropriate for this page, I'm just not sure if this is that proof. --Dantheox 02:36, 14 December 2005 (UTC)

How exactly do we come in Proof in J'(0) from partial derivative of F with respect to ε to partial derivatives of F with respect to f and f'? I don't get it.

It's a standard application of the chain rule -- you can expand out a total derivative with respect to ε in terms of the derivatives with respect to other quantities. --Dantheox 04:02, 7 March 2006 (UTC)

And where does the sum come from? In http://en.wikipedia.org/wiki/Chain_rule#Chain_rule_for_several_variables there is a sum, since the f is a sum of u and v. And here we just have F. I'm not very familiar with partial derivatives, just know how to compute simple ones.

Is anybody able to give me some hints about the connection between Euler-Lagrange Methods and Lagrange multipliers? At first glance they seem to be closely related. Maybe somebody can clarify this and maybe add a short note to the articles. Cyc 12:37, 22 September 2006 (UTC)