Re: Dot or Inner ... but not quite

*To*: mathgroup at smc.vnet.net*Subject*: [mg79673] Re: Dot or Inner ... but not quite*From*: Adriano Pascoletti <adriano.pascoletti at gmail.com>*Date*: Wed, 1 Aug 2007 05:11:19 -0400 (EDT)*References*: <f8n2rc$lp9$1@smc.vnet.net>

On Jul 31, 12:27 pm, "Diamond, Mark" <d... at dot.dot> wrote: > I have two equi-length lists, the first of number, the second of > (equi-length) lists of numbers , such as > > l1={1,4,3}; > l2={{1,7},{1,9},{5,2}}; > > I want to produce 1*{1,7}+4*{1,9}+3*{5,2} > > It looks so close to Inner that I thought I could use it in some form, but I > have ended up using > > (#[[1]]*#[[2]])& /@ Transpose[{l1,l2}] > > Is there a better way using one of the builtin functions with which I am > unfamiliar? > > Cheers, > > Mark Diamond Inner[f, l1, l2] gives {f[1, 1] + f[3, 5] + f[4, 1], f[1, 7] + f[3, 2] + f[4, 9]} so Inner[Times, l1, l2] gives the answer to your question: {20,49} Adriano Pascoletti