Re: Summation question

*To*: mathgroup at smc.vnet.net*Subject*: [mg85700] Re: Summation question*From*: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>*Date*: Tue, 19 Feb 2008 07:04:15 -0500 (EST)*Organization*: Uni Leipzig*References*: <fpdu7v$qlq$1@smc.vnet.net>*Reply-to*: kuska at informatik.uni-leipzig.de

Hi, Sum[f[i], {i, {1, 3, 5, 7, 11, 13}}] or Sum[Piecewise[{{f[i], PrimeQ[i]}}], {i, 1, 14}] ?? Regards Jens Robert Pigeon wrote: > Good day all, > > I want to make a summation like this: Sum[f[i],{i, start, > finish}]. What I want is that the sum be over a specific set like > {1,3,5,7,11,13}. So the sum would be : f[1]+f[3]+f[5]+f[7]+f[11]+f[13]. The > set I want to use is the primes. So, how do I use, if possible, Sum over a > specific set ? > > > > Thanks, > > > > Robert > > > > Robert Pigeon > >