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Re: Sum


On Mar 16, 2005, at 5:35 AM, 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.

Sum evaluates its arguments in a nonstandard way,

Sum[Evaluate[x],{k,0,Infinity}]

works.

Regards,

Ssezi


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