Re: how to make conditional summation

*To*: mathgroup at smc.vnet.net*Subject*: [mg55577] Re: [mg55545] how to make conditional summation*From*: DrBob <drbob at bigfoot.com>*Date*: Wed, 30 Mar 2005 03:21:14 -0500 (EST)*References*: <200503290842.DAA07247@smc.vnet.net>*Reply-to*: drbob at bigfoot.com*Sender*: owner-wri-mathgroup at wolfram.com

Three suggestions: 1) Never capitalize the names of your own variables. N is a built-in function, so it's a bad idea to use it this way. 2) Tell us your question. This is perfectly well defined, for instance: Sum[Cos@m,{m,-5,5}] 1+2 Cos[1]+2 Cos[2]+2 Cos[3]+2 Cos[4]+2 Cos[5] and 5 isn't zero, so... what's the problem? 3) If you meant "Sum[f[m],{m,-N,N}] with m != 0", one of these should do it: Sum[f@m, {m, -n, n}] - f[0] Sum[f@m, {m, -n, -1}] + Sum[f@m, {m, 1, n}] or Sum[Boole[n != 0] f@m, {m, -n, n}] Boole is in the kernel in version 5, but before that it was in the Calculus`Integration` package. or... Sum[If[m != 0, f@m, 0], {m, -n, n}] Bobby On Tue, 29 Mar 2005 03:42:29 -0500 (EST), Xiao Jun Jun <xiaoxun at gmail.com> wrote: > Hi, All, > > Say, Sum[f[m],{m,-N,N}] with N != 0 > Any suggestions? > > Regards. > Xun > > > > > -- DrBob at bigfoot.com

**References**:**how to make conditional summation***From:*"Xiao Jun Jun" <xiaoxun@gmail.com>