On Thu, Sep 2, 2010 at 2:11 PM, Ronan Lamy <[email protected]> wrote: > Le jeudi 02 septembre 2010 à 14:58 -0600, Aaron S. Meurer a écrit : >> Here is what I get in master: >> >> In [2]: O(x) + O(exp(1/x)) >> Out[3]: O(exp(1/x)) >> >> In [4]: O(exp(1/x)) + O(x) >> Out[4]: O(exp(1/x)) >> >> Can someone explain to me why O(x + exp(1/x)) = O(exp(1/x))? It seems to me >> that it should be O(x), since exp(1/x) is a decreasing function, so it >> should be O(1) (see plots at http://www.wolframalpha.com/input/?i=exp(1/x)). > > >From the docstring for Order: "Represents O(f(x)) at the point x = 0." > > exp(1/x) goes to infinity for x -> 0, so the result is correct.
Exactly. Otherwise I also spent lots of hours with this, so I wrote this howto docstring: http://github.com/sympy/sympy/blob/master/sympy/series/order.py#L25 -- 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.
