On Sat, Jun 4, 2011 at 12:13 AM, Aaron Meurer <[email protected]> wrote: > The problem is that with the Euler-Langrange formulas, you need to be > able to do something like expr.diff(f(t)), which is not allowed by > SymPy because f(t) is not a Symbol. You also need to be able to do > expr.diff(f(t).diff(t)). So the idea is to have something that acts > like f(t) or f(t).diff(t) but looks and acts like a Symbol to > Derivative.
I see. But then there needs to be some way to indicate when a derivative is partial or total, right? Because dx/dt = x'(t) but \partial x/\partial t = 0. A subclass of Symbol can handle the first overloading _eval_derivative and free_symbols, and keeping "internal variables" on which it depends (like time), The second is harder though. Renato -- You received this message because you are subscribed to the Google Groups "sympy" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/sympy?hl=en.
