Toronto Math Forum
APM3462019 => APM346Lectures & Home Assignments => Topic started by: Rhamel on April 09, 2019, 05:30:05 PM

When we are asked to "find the EulerLagrange of [some functional T[v]]" are we supposed to :
a) differentiate T[v+$\epsilon$ w] w.r.t to w and evaluate at $\epsilon = 0$ to get the EL, or
b) just plug the Lagrangian into
$$\frac{\partial}{\partial x_j} \frac{\partial \mathcal{L}}{\partial v_{x_j}} = \frac{\partial \mathcal{L}}{\partial v}$$

You understand, that in the left there is summation with respect to $j$?

yes