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Groups > comp.soft-sys.math.mathematica > #1374

Re: Series holding the final sum

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You can also do this:

ss = Sum[(-1)^(n + 2) x^(2 n + 1)/(2 n + 1), {n, 0, 5}];
CirclePlus @@ Select[-CoefficientList[ss, x], # != 0 &]

or

infix = Infix[Select[-CoefficientList[ss, x], # != 0 &], "+"]

The numerical result can be retrieved with:

Plus @@ First@infix

-(2578/3465)

Bobby

On Thu, 31 Mar 2011 03:58:40 -0500, Harvey P. Dale <hpd1@nyu.edu> wrote:

> Select[-CoefficientList[ss,x],#!=0&]
>
> 	Best,
> 	Harvey
>
> -----Original Message-----
> From: Jon Joseph [mailto:josco.jon@gmail.com]
> Sent: Wednesday, March 30, 2011 5:10 AM
> To: mathgroup@smc.vnet.net
> Subject:   Series holding the final sum
>
> All:  Given the following sum:
>
> Sum[(-1)^(n + 2) x^(2 n + 1)/(2 n + 1), {n, 0, 5}]
>
> which generates:
>
> x - x^3/3 + x^5/5 - x^7/7 + x^9/9 - x^11/11
>
> I would like to replace x with -1 (%/.x->-1) without the sum being
> evaluated so I end up with
>
> -1+1/3-1/5+1/7-1/9+1/11
>
> So far I have not been able to find a way to Hold, HoldForm, Unevaluate,
> or Defer and keep getting -2578/3465.  Thanks. Jon
>
>
> ______________________________________________________________________
> This email has been scanned by the MessageLabs Email Security System.
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> ______________________________________________________________________
>


-- 
DrMajorBob@yahoo.com

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Re: Series holding the final sum DrMajorBob <btreat1@austin.rr.com> - 2011-04-01 07:31 +0000

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