2006/4/8, He, Yulei <[EMAIL PROTECTED]>:
>
> Hi, there.
>
>
>
> How do I calculate the cross-product in the form of
> \sum_{i=1}^{n}X_{i}^{t} \Sigma X_{i} using R code without using do loop?
> X_{i} is the covariate matrix for subject I, \Sigma is the covariance
> matrix.If I don't miss something in the matrix algebra, maybe you want the following: > crossprod(crossprod(t(X),sigma),X) where X is the 'n by d' matrix of covariates, and sigma the 'd by d' matrix of assigned covariances. Antonio, Fabio Di Narzo. Thanks for your help. > > > > Yulei > > > > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html > [[alternative HTML version deleted]] ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
