Aaron, On Sun, Mar 25, 2012 at 5:27 PM, Aaron Meurer <asmeu...@gmail.com> wrote: > There is already support in the git master for taking derivatives with > respect to functions and derivatives: > > In [153]: diff(x*f(x)**2 + f(x)*diff(f(x), x), f(x)) > Out[153]: > d > 2⋅x⋅f(x) + ──(f(x)) > dx > > In [154]: diff(x*f(x)**2 + f(x)*diff(f(x), x), diff(f(x), x)) > Out[154]: f(x) > > So your boilerplate code would be unnecessary in SymPy.
What about if f(x) isn't just f(x) but g(x,y,z,t)? And taking derivatives with respect to that (and its derivatives). That's the situation I'm in. I knew the f(x) case was implemented, but I didn't think that the g(x,y,z,t) case was. For straightforward dynamics problems, the f(x) case is enough, but once you add in flexible bodies, you need the g(x,y,z,t) case as well along with all possible derivatives. I'd love to see a full Euler-Lagrange equation implementation. Most (including mine), only do the standard Euler-Lagrange equation, but for different functionals, you can can get much more complicated Euler-Lagrange equations than just the standard one. But, to get the full one, you'd need to implement Calculus of Variations and support taking a variation with respect to a functional. I have a basic implementation in Maple, but it's not particularly robust. Cheers, Tim. -- Tim Lahey PhD Candidate, Systems Design Engineering University of Waterloo http://about.me/tjlahey -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to sympy@googlegroups.com. To unsubscribe from this group, send email to sympy+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
