>using not just calculus but calculus-of-variations, a subject nearly as old as Newtonian mechanics [1] bridges aren't catenaries and Euler and Lagrange gave u

>using not just calculus but calculus-of-variations, a subject nearly as old as Newtonian mechanics [1] bridges aren't catenaries and Euler and Lagrange gave us the Euler-Lagrange equations, not Newton.