R help - Apr 2008 - Help on vectorizing

Hi,

I am a newbie at R and was thinking of ways to vectorize this loop but can't
quite figure out if anything more can be done :

Here the dimensions of the arrays are (N=2000, K=2, D=1000):
responsibilities : N * K
pi: K
corp: N*D
theta: K*D

    for (n in 1:N)
        {
            for (k in 1:K)
            {
                responsibilities[n, k] <- (pi[k]) +
(log1p(dmultinom(x=corp[n, ], prob=exp(theta[k, ]))))
            }
            denom <- log.sum(responsibilities[n, ])
            responsibilities[n,] <- responsibilities[n, ] - denom
        }


Any help is much appreciated!

thanks.

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