Why am I getting inconsistent reports between FEATURE MEMSTATS and MEMORY in MATLAB 7.6 (R2008a)?

The following Tech Note seems to indicate that a matrix can be as large as the "Maximum Free Contiguous Block Size" reported by executing the 'feature memstats'command in MATLAB:

https://www.mathworks.com/help/matlab/performance-and-memory.html

However, this command resulted in the following output on my 64-bit Windows Server 2003 machine:

    Physical Memory (RAM):
In Use:                             1596 MB (   63ce2000)
Free:                              31002 MB (  791a63000)
Total:                             32599 MB (  7f5745000)
Page File (Swap space):
In Use:                             1870 MB (   74eaa000)
Free:                              33887 MB (  845fc5000)
Total:                             35758 MB (  8bae6f000)
Virtual Memory (Address Space):
In Use:                              928 MB (   3a041000)
Free:                            8387679 MB (7ffc5f9f000)
Total:                           8388607 MB (7fffffe0000)
Largest Contiguous Free Blocks:
1. [at   180401000]             8379758 MB (7fdd6e4f000)
2. [at    7fff0000]                3072 MB (   c0010000)

...

ans =

8.7868e+012

However, executing the following command:

A = zeros(2^40,1,'uint8');

results in an "Out of Memory" error.

Further, executing MEMORY results in the following output:

Maximum possible array:              33885 MB (3.553e+010 bytes) *
Memory available for all arrays:     33885 MB (3.553e+010 bytes) *
Memory used by MATLAB:                 331 MB (3.474e+008 bytes)
Physical Memory (RAM):               32599 MB (3.418e+010 bytes)

Answer 1

[MathWorks Support Team]

The use of FEATURE MEMSTATS to estimate the largest block of contiguous memory is limited to 32-bit Windows platforms as described in the tech note,

https://www.mathworks.com/help/matlab/performance-and-memory.html

On 64-bit platforms, the commands FEATURE MEMSTATS and MEMORY return differing interpretations of available memory.

Executing the following command:

feature memstats

reports the largest memory address block available on the system. This number is in terms of the available memory addresses based on the theoretical limit/process Limit of the architecture (i.e. 32-bit Windows or 64-bit Windows) and not the physical resources that are available.