Re: unexpected behaviour of Sum

*To*: mathgroup at smc.vnet.net*Subject*: [mg126536] Re: unexpected behaviour of Sum*From*: perplexed <yudumbo at gmail.com>*Date*: Fri, 18 May 2012 05:22:41 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*References*: <joq5h8$r20$1@smc.vnet.net> <jot5hm$am0$1@smc.vnet.net>

Thanks to everybody. It is surely true I could write a better definition for my functions (sod was just an example), but still I do think that this is an imperfection in the documentation of Sum. First of all, this SymbolicSumThreshold option is never cited in the documentation of Sum. In general, there is never a hint to the fact that Sum will try to sum symbolically in the case of a definite sum. If I did know, I would have considered writing a better function. On the contrary, in the documentation of Sum I read : "If the range of a sum is finite, i is typically assigned a sequence of values, with f being evaluated for each one." and "If a sum cannot be carried out explicitly by adding up a finite number of terms, Sum will attempt to find a symbolic result. In this case, f is first evaluated symbolically." With due respect, I think that maybe a couple of lines should be added to the documentation at least in the "Possible issues" section.

**Follow-Ups**:**Re: unexpected behaviour of Sum***From:*Murray Eisenberg <murray@math.umass.edu>