Matlab not using all available RAM in OSX 10.7

I am trying to process a large image file in Matlab 2012a on a Mac Pro with 32 GB of memory. I keep getting out of memory errors. When I look at activity monitor, matlab is never using more than ~2.0GB of RAM but has ~30GB of page outs to virtual memory (compared to ~15GB of page ins). It seems like it should be using more physical memory, but will not. I checked ulimit and it says the OS memory limit is set to unlimited. I tried starting my script with unix('ulimit -m unlimited') and still had the same problem. Anyone have any idea what is going on ?

[Ken Atwell]

Strange, can you try something exceedingly simple: Reboot your machine, start MATLAB, and execute...

 A=zeros(1e9,1);

...and nothing else. Then look at the Activity Monitor. Here the values I get on my Mac Pro (only 12 GB RAM; I chose the above value to get close to filling all physical memory on my computer) running Lion with the latest updates:

• Real Mem: 7.86 GB
• Virtual Mem: 8.21 GB
• Private Mem: 7.7.5 GB
• Shared Mem: 44.9 MB

I don't expect identical results, but these values should be of roughly the same magnitude. What values do you see?