[S] is there a cumouter() like function?

[Fei Chen <fchen@stern.nyu.edu>]

hi all,

i'm trying to do the following, is there a way to avoid the loop?

a_matrix(rnorm(30),10,3) # some random N x 3 matrix
b_matrix(0,3,3) 
for(i in 2:10)
        b_b+a[i-1,]%o%a[i,]

it seems this sort of question is often asked, but i couldn't find an
answer on the s-news archive.

thanks, fei

ps.  can someone give me an example of unavoidable loop? and under what
general conditions when this happens?





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