Re: Sum

*To*: mathgroup at smc.vnet.net*Subject*: [mg55250] Re: [mg55175] Sum*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Thu, 17 Mar 2005 03:30:33 -0500 (EST)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

Sum[Exp[-k],{k,0,Infinity}] E/(-1 + E) As stated in the Help entry for Sum, Sum evaluates its arguments in a non- standard way. Use Evaluate: x=Exp[-k]; Sum[Evaluate[x],{k,0,Infinity}] E/(-1 + E) Bob Hanlon > > From: mjumbo <mjumbo at nm.ru> To: mathgroup at smc.vnet.net > Date: 2005/03/16 Wed AM 05:35:51 EST > To: mathgroup at smc.vnet.net > Subject: [mg55250] [mg55175] Sum > > 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. > >