Implement functional derivative and Euler-Lagrange equation

[golam-m-hossain]

One of the elementary tool that is often needed to compute equation of motion in Physics, is functional derivative. This along with the implementation of Euler-Lagrange equation will make Sage extremely useful for physicists.

Component: symbolics

Issue created by migration from https://trac.sagemath.org/ticket/6466

[kcrisman]

comment:1

See also this ask.sagemath discussion.

[pretentious7]

comment:2

Would a good step toward this be adding dynamicsymbols from here? https://docs.sympy.org/latest/modules/physics/mechanics/lagrange.html

Sorry for bumping old thread, but I'm interested in working on this.