I am running CAR models in GeoBUGS on maps with fairly large numbers of
cells (5000-10000). I have found that setting the program to sample both p
and rho (via the inference/sample monitor tool) causes "illegal memory
write" at the same iteration (~8000 iterations), at which point the program
is using ~ 1.5GB of memory. (This occurs with both WINBUGS 1.4.1 and
OpenBUGS 2.2.0). If I set it to only sample either p or rho, it will run for
twice as many iterations without the error. I tried switching to WINXP's
64-bit version on a computer with 4GB of RAM. WINBUGS runs well on the
64-bit system, but still gives illegal memory write at the same point
(~1.5GB memory usage).  Theoretically, a 32-bit application can access up to
2.7GB of RAM on XP64-bit, so I am wondering if:
1) Is there an option for increasing the maximum RAM WinBUGS can access,
similar to how maximum object size can be set via options in R?
2) If not, what other workarounds might be possible? I see that the Summary
Monitor Tool might provide one option, but the manual says to use with
caution as statistics are approximate. Would increasing the thinning value
in the sample monitor tool or the update tool help?
--
Carlos Carroll, Ph.D.
Klamath Center for Conservation Research
PO Box 104
Orleans, CA 95556 

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