The answer to your first question is
sum(x)8sum(y) - sum(x*y)
and for the second one
x %*% R %*% y - sum(x*y*diag(R))
--- On Thu, 3/7/08, Murali Menon <[EMAIL PROTECTED]> wrote:
> From: Murali Menon <[EMAIL PROTECTED]>
> Subject: [R] multiplication question
> To: [EMAIL
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: [EMAIL PROTECTED]: [EMAIL PROTECTED]:
Re: [R] multiplication
for 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 <[EMAIL PROTECTED]> wrote:
>
> folks,
>
> is there a clever way to compute the sum of the produ
I'm sorry:
sum(v1 %o% v2 - diag(v1*v2))
On Wed, Jul 2, 2008 at 6:03 PM, Henrique Dallazuanna <[EMAIL PROTECTED]>
wrote:
> Try something about like this:
>
> v1 %o% v2 - diag(v1*v2)
>
> On Wed, Jul 2, 2008 at 1:30 PM, Murali Menon <[EMAIL PROTECTED]> wrote:
>
>>
>> folks,
>>
>> is there a clever
Hi Murali,
Just an idea, probably not the best :
x<-1:4
y<-1:6
z<-matrix(1:(length(x)*length(y)),nrow=length(x))
I <- matrix(1,nrow=length(x),ncol=length(y))
I[row(I)==col(I)] <- 0
sum (outer (x, y, '*') * I)
sum (outer (x, y, '*') * z * I)
Hope this helps,
Nael
On Wed, Jul 2, 2008 at 6:3
Try something about like this:
v1 %o% v2 - diag(v1*v2)
On Wed, Jul 2, 2008 at 1:30 PM, Murali Menon <[EMAIL PROTECTED]> 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 vect
Behalf Of Murali Menon
> Sent: Thursday, 3 July 2008 4:31 a.m.
> To: [EMAIL PROTECTED]
> Subject: [R] multiplication question
>
>
> folks,
>
> is there a clever way to compute the sum of the product of
> two vectors such that the common indices are not multiplied toget
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 compute
Sum (X[i] * Y[j])
i != j
where i != j
also, what if i wanted
Sum (X[i] * Y[j] * R[i, j])
i != j
w
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