Re: sum with lists
- To: mathgroup at smc.vnet.net
- Subject: [mg40553] Re: sum with lists
- From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
- Date: Thu, 10 Apr 2003 03:36:44 -0400 (EDT)
- Organization: Universitaet Leipzig
- References: <b70npo$9gd$1@smc.vnet.net>
- Reply-to: kuska at informatik.uni-leipzig.de
- Sender: owner-wri-mathgroup at wolfram.com
Hi, d={{x0,y0,z0},{x1,y1,z1},{x2,y2,z1}, {xn,yn,zn}}; Plus @@ (#[[1]]*#[[3]] & /@ d) for Sum[x[i]*z[i],{i,0,n}] or Plus @@ (#[[1]]*#[[3]] & /@ Take[d,n/2]) for Sum[x[i]*z[i],{i,0,n/2}] Regards Jens Nathan Moore wrote: > > Another list question. Suppose that I have the list > d={ > {x0,y0,z0}, > {x1,y1,z1}, > {x2,y2,z1}, > ... > {xn,yn,zn}} > > and now I'd like to calculate the sum, > Sum[x[i]*z[i],{i,0,n/2}] > > I tried > Sum[d[[i, 1]]*d[[i, 3]], {i, 0, 10}] > with little success > > thanks, > > Nathan Moore, > University of Minnesota Physics