@asmeurer. I only know they are used in summing the "half-integer" spins. But i have no idea regarding the rules used.
On Wednesday, February 4, 2015 at 12:48:58 AM UTC+5:30, Aaron Meurer wrote: > > Do physics applications actually use summation notation with noninteger > limits? If so, what convention do they use? > > Aaron Meurer > > On Tue, Feb 3, 2015 at 2:11 AM, Gaurav Dhingra <axyd...@gmail.com > <javascript:>> wrote: > >> 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>: >>> >>>> 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. >>>> 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/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+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/1e25d326-1524-44cd-8c16-4cbb841c7173%40googlegroups.com >> >> <https://groups.google.com/d/msgid/sympy/1e25d326-1524-44cd-8c16-4cbb841c7173%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/9feab553-a1c5-46d5-81d6-c684b5a684e6%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
