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. > __________ > www.newmail.ru -- Íîâàÿ Ïî÷òà: âñå ïî-íîâîìó.