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. ? >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "sympy" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to sympy+un...@googlegroups.com. >>>> To post to this group, send email to sy...@googlegroups.com. >>>> Visit this group at http://groups.google.com/group/sympy. >>>> To view this discussion on the web visit https://groups.google.com/d/ >>>> msgid/sympy/697cda0a-62db-411e-bf10-a9d601bbcb69%40googlegroups.com >>>> <https://groups.google.com/d/msgid/sympy/697cda0a-62db-411e-bf10-a9d601bbcb69%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> -- >> You received this message because you are subscribed to the Google Groups >> "sympy" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to sympy+un...@googlegroups.com <javascript:>. >> To post to this group, send email to sy...@googlegroups.com <javascript:> >> . >> Visit this group at http://groups.google.com/group/sympy. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/sympy/b6924d03-fbbf-4c63-ad87-92a9ac5e0c12%40googlegroups.com >> >> <https://groups.google.com/d/msgid/sympy/b6924d03-fbbf-4c63-ad87-92a9ac5e0c12%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> For more options, visit https://groups.google.com/d/optout. >> > > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/1e25d326-1524-44cd-8c16-4cbb841c7173%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.