# A question about notation on derivatives

by atomqwerty
Tags: derivatives, notation
 P: 94 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 $e^{\lambda}$. The problem asks for the derivative $\frac{\delta L}{\delta \lambda}$. What this notation corresponds to? Thanks
 Math Emeritus Sci Advisor Thanks PF Gold P: 39,323 That is the "total derivative", $$\frac{\delta L}{\delta \lambda}= \frac{\partial L}{\partial x}\frac{dx}{d\lambda}+ \frac{\partial L}{\partial y}\frac{dy}{d\lambda}$$ by the chain rule. It more often seen in physics texts than math texts. Math texts would just us "$dL/d\lambda$".