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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>