It should probably just order the variables alphabetically or by hash value from the start. On the other hand, this is not always true (see http://en.wikipedia.org/wiki/Symmetry_of_second_derivatives) , namely, the function has to have continuous second partials. Is there a way to tell SymPy to assume this?
Aaron Meurer On May 2, 2009, at 8:19 AM, Alan Bromborsky wrote: > > > The following does not simplify to zero in sympy: > > -D(F__x(x, y, z), z, y) - D(F__y(x, y, z), x, z) - D(F__z(x, y, z), y, > x) + D(F__x(x, y, z), y, z) + > D(F__y(x, y, z), z, x) + D(F__z(x, y, z), x, y) > > > sympy does not know that D(F__x(x, y, z), z, y) = D(F__x(x, y, z), > y, z) > > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
