Re: a big limit of mathematica?

Dave Seaman wrote:

On Tue, 20 Sep 2005 09:31:47 -0700, Richard J. Fateman wrote:

(RJF) Mathematica's limitations are very likely related
to the amount of virtual memory it is allocated by
the operating system, and perhaps by the maximum
amount of memory Mathematica declares it is going to
use.  Such limits are much smaller than the 64 bit
limit on address space.  In particular,
doing


(DS) That's not the way virtual memory works, at least on any decent operating
system. 

I thought we were talking about Windows?

The amount of virtual memory that is allocated to an application 
by the operating system is determined dynamically and is limited only by
the total amount of swap space available on the computer.


There is a nice discussion here
http://www.rsinc.com/services/techtip.asp?ttid=3346
which suggests that there are a number of other factors in Windows.


(DS)  That means the G5 successfully
computed an array that exceeds the size of its physical memory.


That's certainly the way it is supposed to work. The G5 is not
running Windows.

I am using a Windows 2000 system right now, not XP, but I find
these instructions from the system help command ...

"To change the size of the virtual memory paging file

Open System in Control Panel.
On the Advanced tab, click Performance Options, and under Virtual memory, click Change.
In the Drive list, click the drive that contains the paging file you want to change.
Under Paging file size for selected drive, type a new paging file size in megabytes in the Initial size (MB) or Maximum size (MB) box, and then click Set.
If you decrease the size of either the minimum or maximum page file settings, you must restart your computer to see the effects of those changes. Increases typically do not require a restart...."

 So maybe LumisRob needs to change the virtual memory paging file.
Maybe he even needs to restart.  Or not.

Still, the response of Mathematica to an attempt to exceed
possible allocation of memory should be something other than
"You lose everything you computed so far."





.

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