Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2007
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2007

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Fun with zero sums

  • To: mathgroup at smc.vnet.net
  • Subject: [mg77390] Re: [mg77133] Fun with zero sums
  • From: Devendra Kapadia <dkapadia at wolfram.com>
  • Date: Thu, 7 Jun 2007 04:08:46 -0400 (EDT)
  • References: <200706040756.DAA06337@smc.vnet.net>

On Mon, 4 Jun 2007, David W.Cantrell wrote:

> I'm using Mathematica 5.2; if Mathematica 6 behaves differently, I'd be
> interested to know it.
>
> In[1]:= Sum[0, {n, 1, Infinity}]
>
> Out[1]= 0
>
> which is as, I think, it should be. But then we have the following sums,
> which all disappoint, in different ways.
>
> In[2]:= Sum[0^n, {n, 1, Infinity}]
>
> Out[2]= Sum[0^n, {n, 1, Infinity}]
>
> In[3]:= Sum[0^(2*n - 1), {n, 1, Infinity}]
>
> Warning about "Infinite expression encountered."
>
> Out[3]= ComplexInfinity
>
> In[4]:= Sum[0^(2*n + 1), {n, 1, Infinity}]
>
> Warning about "Indeterminate expression encountered."
>
> Out[4]= Indeterminate
>
> Of course, Out[2..4] should have been 0, just like Out[1].
>
> David W. Cantrell
>
Hello David,

Thank you for these examples showing problems with sums involving 
powers of 0.

The incorrect answers in Out[3] and Out[4] are due to a missing check
for 0 while trying to simplify the summand in each case. As noted by
others, In[2] returns 0 in Mathematica 6. We will continue to work
on improved handling of important special cases such as the ones
given by you.

I apologize for the inconvenience caused by the incorrect behavior.

Sincerely,

Devendra Kapadia,
Wolfram Research, Inc.


  • Prev by Date: Re: Re: Re: Problem with Mathematica 6
  • Next by Date: Re: Value of E
  • Previous by thread: Fun with zero sums
  • Next by thread: Re: Fun with zero sums