Luke, On Mon, Apr 2, 2012 at 1:23 PM, Luke <hazelnu...@gmail.com> wrote: >> Did you see my email about the Euler-Lagrange equations of motion that >> I sent earlier today? One important point is that there is absolutely >> no reason to have a custom Lagrangian class. You can just build the >> Lagrangian as a standard sympy expression. > > One reason to have a custom Lagrangian class is that it helps keep > track of systems where you have a large number of > particles/bodies/constraints/interacting forces. For simple systems > you can surely write the Lagrangian in a line or two, but for more > interesting systems, it becomes onerous and error prone to do this > "manually". Having a class which allows you to pass it a list of > particles/bodies, and the forces/torques acting on them, as well as > any kinematic constraints that may be present, greatly simplifies the > work the user must do and reduces the likelihood of making a mistake. > I see many reasons to have a custom Lagrangian class.
OK, I can see that such a class would be useful for more complex systems, especially when things like constraints come into play. But, users should always be able to define a Lagrangian using regular sympy expressions. Also, the underlying Euler-Lagrange equations should work with regular sympy expressions as well. Cheers, Brian > Luke > > -- > 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. > -- Brian E. Granger Cal Poly State University, San Luis Obispo bgran...@calpoly.edu and elliso...@gmail.com -- 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.
