Re: Sum
- To: mathgroup at smc.vnet.net
- Subject: [mg55211] Re: Sum
- From: bghiggins at ucdavis.edu
- Date: Thu, 17 Mar 2005 03:28:29 -0500 (EST)
- References: <d192qe$ng4$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
mjumbo,
Sum has the attribute HoldAll, so its arguments are held in an
unevaluated form. Simply wrap the first argument of Sum with Evalaute
Sum[Evaluate[x], {k, 0, Infinity}]
Cheers,
Brian
mjumbo wrote:
> Can sombody explain me why
>
> Sum[Exp[- k], {k, 0, Infinity}]
>
> gives the correct result, while the following (imho equivalent)
statements
>
> x = Exp[-k]
> Sum[x, {k, 0, Infinity}]
>
> don't? What should I do to make it work? It is rather vexing to
copy/paste long expressions instead of using short placeholders like x.
> __________
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