Mathematica 9 is now available
Services & Resources / Wolfram Forums / MathGroup Archive
-----

MathGroup Archive 2012

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

Search the Archive

Re: Incorrect Summation

  • To: mathgroup at smc.vnet.net
  • Subject: [mg129200] Re: Incorrect Summation
  • From: amzoti <amzoti at gmail.com>
  • Date: Thu, 20 Dec 2012 03:27:31 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • Delivered-to: l-mathgroup@wolfram.com
  • Delivered-to: mathgroup-newout@smc.vnet.net
  • Delivered-to: mathgroup-newsend@smc.vnet.net
  • References: <20121218073534.C7529694B@smc.vnet.net> <kas30a$ciq$1@smc.vnet.net>

On Wednesday, December 19, 2012 1:56:26 AM UTC-8, Murray Eisenberg wrote:
> What did you type, exactly, for Wolfram|Alpha? I tried several "obvious" things, e.g.,
> 
>   sum cos(log(log(k)))/log(k) for k from 2 to infinity
> 
> but WA was unable even to interpret it correct as asking for the sum of an infinite series.
> 
> On Dec 18, 2012, at 2:35 AM, amzoti <amzoti at gmail.com> wrote:
>
> > Hi All,
> 
> > can someone try this and see if it returns an incorrect result?
> 
> > Sum[Cos[Log[Log[k]]]/Log[k],{k,2,Infinity}]
> 
> > I tried it on WA and believe the result is incorrect.
> 
> > Thanks.
> ---
> 
> Murray Eisenberg                                    murray at math.umass.edu
> 
> Mathematics & Statistics Dept.      
> 
> Lederle Graduate Research Tower            phone 413 549-1020 (H)
> 
> University of Massachusetts                               413 545-2838 (W)
> 
> 710 North Pleasant Street                         fax   413 545-1801
> 
> Amherst, MA 01003-9305

Just copy and paste the expression as-is: 
Sum[Cos[Log[Log[k]]]/Log[k],{k,2,Infinity}] 

For this example, if you increase the number of points to max on WA, you can see where I think the result is going astray and why this is returning an incorrect result.

Aside:
It is odd that sometimes WA accepts the user inputs in standard notation, but other times, it seems to get confused.

I would think that if a user knows how to type Mathematica standard syntax correctly, that WA should be able to accept it.

Thanks -A



  • Prev by Date: Re: will not plot functions when one of the
  • Next by Date: Re: will not plot functions when one of the
  • Previous by thread: Re: Incorrect Summation
  • Next by thread: Re: Incorrect Summation