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 <axyd0...@gmail.com> 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+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 > <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. 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