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A question about notation on derivatives

  1. Jan 21, 2013 #1
    Hi,
    I didn't put this into homework since is only a question about notation:

    In a problem, given a Lagrangian and a transformation (x,y) -> (x',y'), where these x' and y' depend on λ, in particular like [itex]e^{\lambda}[/itex]. The problem asks for the derivative [itex]\frac{\delta L}{\delta \lambda}[/itex]. What this notation corresponds to? Thanks
     
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  3. Jan 21, 2013 #2

    HallsofIvy

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    That is the "total derivative",
    [tex]\frac{\delta L}{\delta \lambda}= \frac{\partial L}{\partial x}\frac{dx}{d\lambda}+ \frac{\partial L}{\partial y}\frac{dy}{d\lambda}[/tex]
    by the chain rule.

    It more often seen in physics texts than math texts. Math texts would just us "[itex]dL/d\lambda[/itex]".
     
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