Could someone explain who came up with the specific equation first?
http://en.wikipedia.org/wiki/Euler-Lagrange
makes it sound like Lagrange got it first, in 1755, then sent it to Euler.
but:
http://en.wikipedia.org/wiki/Calculus_of_variations
sort of makes it sound like Euler got it first in the 1730s.
It seems like a straightforward question, but I can't find an answer anywhere. Who came up with the equation, Euler or Lagrange? And what precisely did the other man contribute to get his name on there?