I don't understand. How is ∂x/∂t != dx/dt? Aaron Meurer
On Fri, Jun 3, 2011 at 9:43 PM, Renato Coutinho <[email protected]> wrote: > 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. > > -- 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.
