R help - Aug 2008 - function as.dist failed on large matrix on 64bit machine

Hi there,

I'm having a problem with as.dist when I tried to convert a numerical 
matrix to dist. The data matrix is 10^4 by 10^4. I got the following:

d <- as.dist(dat)
Error: cannot allocate vector of size 762.9Mb

I need convert "dat" to dist because I will use hclust to do some 
clustering analysis.

The machine is 2Gb memory 64bit Linux, and I also failed on a 16Gb 
memory 64bit Linux. Is there anyway that I can
get around it? Or how large is the limitation on my machine? Thanks in 
advance.

Best,
Baoqiang