Re: Sum
- To: mathgroup at smc.vnet.net
- Subject: [mg55213] Re: Sum
- From: Peter Pein <petsie at arcor.de>
- Date: Thu, 17 Mar 2005 03:28:31 -0500 (EST)
- References: <d192qe$ng4$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
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.
> __________
> www.newmail.ru -- Íîâàÿ Ïî÷òà: âñå ïî-íîâîìó.
>
Attributes@Sum
{HoldAll,Protected,ReadProtected}
^^^^^^^
so
x=Exp[-k];
Sum[Evaluate@x,{k,1,Infinity}]
will give what you want
--
Peter Pein
Berlin