[R] how can I do this sum?

[Rolf Turner]

On 12/08/2008, at 7:09 AM, dott wrote:

>
> Hi,
>
> Suppose I have a vector in real number
> (x1, x2, x3, x4, x5, x6)
>
> My question is how I can get
> x5*x3*x1 + x6*x4*x2 ?

	v <- c(x1, x2, x3, x4, x5, x6)
	m <- matrix(v,ncol=3)
	sum(apply(m,1,prod))

This could easily be ``generalized'' and bundled up in a function if  
so desired.

		cheers,

			Rolf Turner

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