Re: Multiple Sums in Mathematica

*To*: mathgroup at smc.vnet.net*Subject*: [mg53704] Re: [mg53696] Multiple Sums in Mathematica*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Mon, 24 Jan 2005 03:37:25 -0500 (EST)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

Presumably, you intend f to be a function of the indices. multiSum[f_, n_Integer, maxIndex_:M, index_String:"i"] := Module[{var,k}, var=ToExpression[Table[index<>ToString[k],{k,n}]]; Fold[Sum[#1,{#2,1,maxIndex}]&, f[Sequence@@var],Reverse[var]]]; multiSum[f,3] Sum[f[i1, i2, i3], {i1, 1, M}, {i2, 1, M}, {i3, 1, M}] multiSum[f,3,r] Sum[f[i1, i2, i3], {i1, 1, r}, {i2, 1, r}, {i3, 1, r}] multiSum[f,3,M,"k"] Sum[f[k1, k2, k3], {k1, 1, M}, {k2, 1, M}, {k3, 1, M}] Bob Hanlon > > From: sbrandt at physics.wustl.edu (Sebastian Brandt) To: mathgroup at smc.vnet.net > Date: 2005/01/23 Sun AM 02:02:26 EST > To: mathgroup at smc.vnet.net > Subject: [mg53704] [mg53696] Multiple Sums in Mathematica > > Hello, > > I want to perform a nested sum, where the number of summations is not > specified. I.e., I am looking for a way to implement the sum > > sum[ f, {i1, 1, M}, {i2, 1, M}, ..., {in, 1, M} ] > > Does anbody know how to do this for arbitrary n? > > Regards, > > Sebastian Brandt > >