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Re: Sum


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


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