Euler-Lagrange equations

  • Thread starter Lapidus
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  • #1
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Main Question or Discussion Point

In this document, how do I get 3.2 on page 12? I assume it is the Euler-Lagrange equation given in 3.1 just rewritten. But how?

Many thanks in advance
 

Answers and Replies

  • #2
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Any hints? I think in 3.1 they take the time derivative to get to 3.2. But I still can't see how that works out.
 
  • #3
dextercioby
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Well, then you need to go back to your calculus text and check the chain rule.

[tex] \frac{d}{dt} \frac{\partial L(q,\dot{q})}{\partial \dot{q}^{i}} =\frac{\partial^2 L}{\partial \dot{q}^{i} \partial q^{j}} \frac{dq^{j}}{dt} + ... [/tex]
 

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