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List:       r-help
Subject:    Re: [R] How to do it without for loops?
From:       "Gabor Grothendieck" <ggrothendieck () gmail ! com>
Date:       2006-02-28 13:43:15
Message-ID: 971536df0602280543i4c848426v249bd9c74c1897be () mail ! gmail ! com
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Try:

crossprod(x)

or

t(x) %*% x

On 2/28/06, ronggui <ronggui.huang@gmail.com> wrote:
> This is the code:
>
> x<-matrix(rnorm(20),5)
> y<-list()
> for (i in seq(nrow(x))) y[[i]]<-t(x[i,,drop=F])%*%x[i,,drop=F]
> y[[1]]+y[[2]]+y[[3]]+y[[4]]+y[[5]]
>
> How can I do it without using for loops?
> Thank you in advance!
> --
> ronggui
> Deparment of Sociology
> Fudan University
>
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>

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