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From: Ben on 16 Sep 2006 22:51
Anyone know what causes this message?
I get when trying to find the limit as n approaches infinity of sigma
from 1 to n of one over x plus x.

From: TE on 17 Sep 2006 05:56

Ben wrote:
> Anyone know what causes this message?
> I get when trying to find the limit as n approaches infinity of sigma
> from 1 to n of one over x plus x.

with sigma if you mean the summation than
have a look at "advanced user's reference manual" for the
hp49g+/hp48gII at page3-212:

\GS (Summation)
Type: Function
Description: Summation Function: Calculates the value of a finite
series.

it will not help, but maybe it informs a bit.

tom

From: Steen Schmidt on 17 Sep 2006 07:26
Ben wrote:

> Anyone know what causes this message?
> I get when trying to find the limit as n approaches infinity of sigma
> from 1 to n of one over x plus x.

Please state mathematical expressions algebraically instead of in text
- it makes it much easier to understand (and to not misunderstand).

As I understand it (after reading your question a dozen times) you are
trying to evaluate 'lim(SIGMA(X=1,n,1/X+X),n=inf)'?

If you did it step-by-step (first evaluate the sum, then take the
limit), you'd probably have an idea of which step went wrong. In this
case the summation goes fine but the limit function chokes on the
result. Which operators could lim choke on? Since only +, -, *, /, ^
and Psi are represented, I'd venture a guess and say that the operator
that is not implemented in the SERIES function (which is apparantly
used by lim) is Psi.

Another one not implemented is ! (the factorial operator).

Regards
Steen
From: acl on 18 Sep 2006 10:14
Ben wrote:
> Anyone know what causes this message?
> I get when trying to find the limit as n approaches infinity of sigma
> from 1 to n of one over x plus x.
>

Hi Ben,
Out of curiosity, what do you expect this limit to be?
Cheers.
From: Chris Smith on 18 Sep 2006 11:06
acl <achilleaslazarides(a)yahoo.co.uk> wrote:
> Hi Ben,
> Out of curiosity, what do you expect this limit to be?
> Cheers.

Good question. The ratio test is indeterminate (the limit is one), but
the series doesn't appear to be converging to anything as n gets up to
the 1 million range. I'd guess the correct answer is +inf. I am not
great at this stuff, but I don't see a way to establish that as fact,
rather than supposition. (I'm not Ben; just jumping in.)

--
Chris Smith
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