On Tue, Apr 24, 2012 at 5:16 PM, Tom Bachmann <e_mc...@web.de> wrote:
>> I agree. Can you open an issue for this in our issue tracker
>> (http://code.google.com/p/sympy/issues/list)?
>>
>> We can do hypergeometric series, which is why the summation() function
>> is so powerful in the git master, but I think it's not recognizing
>> this one as such because it's a finite sum (Tom, please correct me if
>> I'm wrong). If you use the fact that binomial(n, k) == 0 for k> n,
>> and replace n with oo in the summation limits, you get:
>>
>
> I was about to say precisely that.
So any thoughts on how to fix it. I guess we should try to recognize
if the summand is zero for all but finitely many values. And then do
some manipulation on the indices.
By the way, I just noticed:
In [156]: summation( binomial(n,k), (k,n - 1, oo))
Out[156]:
ⅈ⋅π
n - ℯ
That exp_polar() should probably be evaluated in the result.
Aaron Meurer
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