Re: FullSimplify[Sum[1/(n^2 +n+1)^2,{n,1,p}]]?

• To: mathgroup at smc.vnet.net
• Subject: [mg8384] Re: FullSimplify[Sum[1/(n^2 +n+1)^2,{n,1,p}]]?
• From: "w.meeussen" <meeussen.vdmcc at vandemoortele.be>
• Date: Tue, 26 Aug 1997 20:41:20 -0400
• Sender: owner-wri-mathgroup at wolfram.com

```At 11:23 23-08-97 -0700, Tom Burton wrote:
>I'm not sure how FullSimplify is suppose to help. If one waits until after
>the rule p->1 is applied, all that is left is "Indeterminant"--nothing to
>simplify! So I tried to FullSimplify that impressive symbolic expression.
>(I should have known better, from past experience with long expressions.)
>After 10 hours of struggle and disk churning, I threw in the towel without
>a result.
>
>
>

Tom,

the point I want to make is of course that somewhere within this expression
a bug prevents evaluation. When the evaluation gives "indeterminate", then
it is too late, the harm already done:

At 10:38 22-08-97 -0500, Victor Adamchik wrote:
>
>run FullSimplify over the output
>
>
>In[4]:= Sum[1/(n^2 +n+1)^2,{n,1,p}];
>
>In[5]:= %/.p->1;
*****************************(wm: no warnings mentioned!! )
>
>In[6]:= FullSimplify[%]
>
>        1
>Out[6]= -
>        9
>
So the error must be platform specific.
I'll copy this to Victor, with the suggestion that different platforms be
tested.
And that whoever sends in a test report, should also report on what platform
it was done. (maybe even with Timings ?)

Two further points:
1/.
I dont want to sneer on the impressive piece of software-artwork that Mma is.
I only want to give helpfull and positive criticism to make it even better.
2/.
In the last year or so, a number of mailings to mathgroup have signalled
platform differences. These are sometimes quite unexpected (cq
FactorInteger[1] as {} or as {1,1} if I remember well).
Apart from minimising \ abolishing them, a FAQ might be devoted to them on
wolfram's web site.

Dr. Wouter L. J. MEEUSSEN
eu000949 at pophost.eunet.be
w.meeussen.vdmcc at vandemoortele.be

```

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