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Groups > comp.soft-sys.math.mathematica > #1251 > unrolled thread

Series holding the final sum

Started byJon Joseph <josco.jon@gmail.com>
First post2011-03-30 09:10 +0000
Last post2011-03-31 09:02 +0000
Articles 2 — 2 participants

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  Series holding the final sum Jon Joseph <josco.jon@gmail.com> - 2011-03-30 09:10 +0000
    Re: Series holding the final sum Peter Pein <petsie@dordos.net> - 2011-03-31 09:02 +0000

#1251 — Series holding the final sum

FromJon Joseph <josco.jon@gmail.com>
Date2011-03-30 09:10 +0000
SubjectSeries holding the final sum
Message-ID<imus1f$hu9$1@smc.vnet.net>
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=

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#1328

FromPeter Pein <petsie@dordos.net>
Date2011-03-31 09:02 +0000
Message-ID<in1fuf$4ik$1@smc.vnet.net>
In reply to#1251
Am 30.03.2011 11:10, schrieb Jon Joseph:
> 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=
>
  For Printing purposes
Infix[Sum[(-1)^(n(* + 2*)) x^(2 n + 1)/(2 n + 1), {n, 0, 5}] /.
    Plus -> List /. x -> -1, "+"]//TraditionalForm
might do what you want.

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