Multiple sum with iterators that cannot equal

*To*: mathgroup at smc.vnet.net*Subject*: [mg19365] Multiple sum with iterators that cannot equal*From*: Eric Spahr <rspahr at worldnet.att.net>*Date*: Fri, 20 Aug 1999 23:09:40 -0400*Organization*: AT&T WorldNet Services*Sender*: owner-wri-mathgroup at wolfram.com

Using multiple summmation signs with condition 'i "not equal" j', evaluation stops immediately as 'i' starts as 1 as does 'j'. My formula requires that the 'i's' and 'j's' together: Sum[Sum[f,{j,1,n}],{i,1,n}] ignore cases where i = j. Or as copied from my notebook: \!\(\(\(\[Sum]\+\(i = 1\)\%n\[Sum]\+\(j = 1\)\%n\)\+\(i != j\)\) \(w\_i\) w\_j\) How do I solve this without some cumbersome loops. Many Thanks Eric Spahr Cottage Technology rspahr at worldnet.att.net