
Thanks for your help, folks.
 
The sum of (outer product less the diagonal) works. 
 
(In the original post, I guess I should have specified 'pair-wise product' of two vectors to be clearer).

Date: Thu, 3 Jul 2008 00:25:10 +0300From: lebatsnok@gmail.comTo: feanor0@hotmail.comSubject: Re: [R] multiplication questionCC: r-help@stat.math.ethz.chfor example ...x <- 1:5 ; y<- 6:8(m <- x %o% y)   # is this what you mean by product of two vectors?sum(m[row(m)!=col(m)])   # or ...sum(m)-sum(diag(m))
On Wed, Jul 2, 2008 at 7:30 PM, Murali Menon <feanor0@hotmail.com> wrote:
folks,is there a clever way to compute the sum of the product of two vectors such that the common indices are not multiplied together?i.e. if i have vectors X, Y, how can i computeSum  (X[i] * Y[j])i != jwhere i != jalso, what if i wantedSum (X[i] * Y[j] * R[i, j])i != jwhere R is a matrix?thanks,murali______________________________________________R-help@r-project.org mailing listhttps://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.
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