performing comparisons with big.matrix (from the bigmemory package in R)

Question

I'd like to perform comparisons with a big.matrix. here is some sample code below:

set.seed(123)

x <- matrix(rnorm(16), ncol=4)

# following line returns a logical matrix
x < 0

y <- as.big.matrix(x)

#I'd like a logical big matrix, or a big matrix of 0's & 1's
#but this line returns an error
y < 0

#this works, but I think it loads the big matrix into ram, which I don't want
#also returns a warning
as.big.matrix(y[,] < 0)[,]