On Mon, Jun 29, 2009 at 11:56 AM, Alex<[email protected]> wrote: > > Hi to all Sympy-people, > > while doing some calculations I stumbled over some strange behavior in > the Sum function. I don't know, if I just misuse it or if something is > broken. > > I try to calculate this: > > m = Symbol('m') > I = Symbol('I') > > s = Sum(exp(m), (m, -I, I)) > > # m should be -2 .. 2 > s = s.subs(I,2).doit() > print(s) > # prints: (exp(-I) - exp(1 + I))/(1 - E) > s.subs(I,2).evalf() > # 11.61... the correct result > > # now just slightly different: > s = Sum(m*exp(m), (m, -I, I)) > > > > # m should be -2 .. 2 > > s = s.subs(I,2).doit() > > print(s) > # Sum(m*exp(m), (m, -I, I)), so it did not expand > # infinite loop here: > s.subs(I, 2).evalf() > > So, how should this be done correctly or is the Sum function only > working in special cases?
I think you found a bug. Could you please report a bug here: http://code.google.com/p/sympy/issues/list together with the traceback? We'll look into it. Many thanks, Ondrej --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
