What i noticed is- what Aaron mentioned "As Mathematica or Maple have no 
problems with this why should it be forbidden or not working nicely in 
Sympy?" and i too think it would be better to have summation over 
non-integers as it is used in Physics.

On Tuesday, February 3, 2015 at 1:37:36 PM UTC+5:30, Christophe Bal wrote:
>
> Hello.
>
> summation(exp(a*x), (x, 1.2, 1.5)) = 0 because a summation with an empty 
> set of indices k is zero by convention. This allows to say that summation 
> over disjoint set A and B is the summation over their union.
>
> Maybe sympy should avoid the use of non integers for the lower and upper 
> bounds.
>
>
> *Christophe BAL*
> *Enseignant de mathématiques en Lycée **et développeur Python amateur*
> *---*
> *French math teacher in a "Lycée" **and **Python **amateur developer*
>
> 2015-02-03 9:01 GMT+01:00 Gaurav Dhingra <axyd...@gmail.com <javascript:>>
> :
>
>> Hi,
>> I want to know about the "summation" function used in sympy.
>>
>> The code should be according to the documentation but for summation, As 
>> @asmeurer had mentioned earlier to me that- "he is not sure regarding the 
>> summation function. That what sympy should be doing with it."
>> https://groups.google.com/forum/#!topic/sympy/z9mZH10UuY0
>>
>> Right now the documentation does not match with the way summation is done 
>> right now.
>>
>> I guess we have choices for implementing the summation function(which i 
>> am noticing are the same as Aaron mentioned in issue #5822 
>> https://github.com/sympy/sympy/issues/5822)
>>
>> 1. Following the way as the documentation says "taking
>>     all integer values from ``start`` through ``end``".
>>     which implies summation like 
>>     summation(exp(a*x), (x, 1.2, 1.5)) would result in a value of zero. 
>> (since no integer value is included between 1.2 and 1.5)
>>     I think this would not be the best way to go. As the this would 
>> result in many function summation to result in a value even if the 
>> summation should not exist.
>>
>> 2. Following the way sympy is going right now i.e evaluate the the 
>> summation for general expression and than substituting the value of lower 
>> and upper limit. (I don't think it would be a good way to go.)
>>
>> 3. Following the way the Wolfram Alpha is doing i.e evaluating making the 
>> lower limit not to be a fraction for evaluating the summation.
>>
>> I would like to work on the issue #5822 . 
>>
>> On Friday, January 23, 2015 at 8:36:18 AM UTC+5:30, Aaron Meurer wrote:
>>>
>>> See https://github.com/sympy/sympy/issues/5822 for a discussion on 
>>> this. I'm not sure what convention SymPy should take, but the documentation 
>>> ought to match it.
>>>
>>> Aaron Meurer
>>>
>>> On Thu, Jan 22, 2015 at 7:56 PM, Gaurav Dhingra <axyd...@gmail.com> 
>>> wrote:
>>>
>>>> Hi all
>>>>
>>>> I ran the following the following code
>>>>
>>>> In[10]: simplify(summation((k), (k, 2, 4.7))) == 
>>>> simplify(summation((k), (k, 2, 4.4)))
>>>> Out[10]: False
>>>>
>>>> I read the documentation of summation function, so according to it the 
>>>> summation includes all the integer values from start to end. But does not 
>>>> seem to follow it.
>>>>
>>>> Is this a bug. ?
>>>>
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>>>
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