[R] vectorization of groups of dot products
gunter.berton at gene.com
Fri Jan 6 23:11:58 CET 2006
colSums(X^2) -- or am I missing something?
-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
"The business of the statistician is to catalyze the scientific learning
process." - George E. P. Box
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Rossi, Peter E.
> Sent: Friday, January 06, 2006 1:56 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] vectorization of groups of dot products
> I have a set of n vectors, x_1, ..., x_n, of the same length.
> I would like to form the vector of dot products -- x_1'x_1,
> ..., x_n'x_n
> the fastest way I can think to do this is to put the vectors into a
> and do
> however, this seems to be very wasteful since this computes n(n+1)/2-n
> dot products.
> Is there a better way using existing functions in R?
> Peter E. Rossi
> Joseph T. and Bernice S. Lewis Professor of Marketing and Statistics
> Editor, Quantitative Marketing and Economics
> Rm 353, Graduate School of Business, U of Chicago
> 5807 S. Woodlawn Ave, Chicago IL 60637, USA
> Tel: (773) 702-7513 | Fax: (773) 834-2081
> R-help at stat.math.ethz.ch mailing list
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