On Tue, May 27, 2008 at 05:22:54AM -0700, astozzia wrote: > > evec=dvecM/sqrt(s.dot(dvec,dvec)) > > Note that I had to use the 'Matrix' and divide my the norm of the > 'list'. Kinda weird...
The problem is that we dont have a true vector support in sympy yet. Specialy you cant define a function of a matrix/vector, thats bad. The derivation of In [4]: vec = s.array([cos(phi(t)),x(t),z(t)]) In [5]: dvec = diff(vec,t) is simply done by a 'elementwise' derivation of the single elements of the vec array. From the mathematical point of view I think this isnt ideal. The 'diff(vec, t)' should better wrapped to something like the jacobion matrix. We had a long discussion an sympy-patches http://groups.google.com/group/sympy-patches/browse_thread/thread/78bf61123b3d7405 where I had sum up my opinion. But you know the time is raw ... :-) And I am not sure if its so good to do this (vector extension) in sympy because I think the sympycore project had a better (mathematical) structure for that. By, Friedrich --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
