[R] Is there a faster way to do this?

[Márcio Resende]

Hi guys, I am still learning R, and not well familiar with all the apply
functions.
I am trying to find faster alternatives to replace the for cycle.
Is there a faster way to do the example below?

nm <- 1000
b <- matrix (rnorm (5000, 0, 1), nrow = 500, ncol = nm)
a <- matrix (0, nm, nm)
for (i in 1 : nm) {
for (j in 1 : nm) {
if ( j == i) {
next }
a[i, j] <- t (b [, i]) %*% b[, j]
}
}

thanks

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