how do you use the change of variable:
[itex]\xi[/itex] = x - ct
on the PDE
+ c ux
where u(t,x) = v(t,x-ct) = v(t,[itex]\xi[/itex])
I am trying to follow the steps of Peter J. Olver in this document http://www.math.umn.edu/~olver/pd_/lnw.pdf
starting on pg 4 but get stuck here...i think i am missing an important calculus concept but cannot figure out what. He says to use the chain rule but i cannot figure out how that helps.
Any help GREATLY appreciated