I added the issue 1499: http://code.google.com/p/sympy/issues/detail?id=1499
Thanks for looking into this. Alexander On Jun 30, 5:27 am, Ondrej Certik <[email protected]> wrote: > 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 -~----------~----~----~----~------~----~------~--~---
