how resolve Get out of memory error in Matlab?

I have matlabR2013a on a 4GiG RAM system and window7. I have the code below:

c = x'*x/(n-d);

x is a 28944*30 double matrix and n and d are 1*1 matrix(a number). when I run this line of code I got error: Out of memory. Type HELP MEMORY for your options.

how can I fix this error? I increase the amount of virtual heap memory but no thing changed!

thanks for your help.

Answer 1

[Guillaume]

If Windows 7 is the 32 bit version, then Matlab can't use more than 2 GB (3GB if you mess about with the OS). If you're using the 32 bit version of Matlab on a 64 bit OS, then you're limited to under 4 GB.

However, the memory footprint of the arrays you're listing is minimal. On my machine x is about 6 MB. You'll need another 6MB free to temporarily store the transpose and possibly 6MB for x/(n-d), but it shouldn't tax your system.

Check how much memory you have free with

memory

In particular, Maximum possible array tells you what is the max. size of a single array.

Check how much the existing variables use with

whos

Clear the variables you don't need.

FInally have a look at this page (and of course do type HELP MEMORY as instructed).

[sasa]

I am using 64 bit version of matlab on a 64 bit OS. result is:

>> memory

Maximum possible array: 2718 MB (2.850e+09 bytes) * Memory available for all arrays: 2718 MB (2.850e+09 bytes) * Memory used by MATLAB: 709 MB (7.435e+08 bytes) Physical Memory (RAM): 4085 MB (4.283e+09 bytes)

• Limited by System Memory (physical + swap file) available.

 whos x
  Name       Size                 Bytes  Class     Attributes

x         30x28944            6946560  double

[Guillaume]

In your question you wrote that the size of x was 28944 x 30, which would result in a c of size 30 x 30. No problem fitting that in memory.

However, according to your whos command, x is actually 30 x 28944, which will result in a c of size 28944 x 28944. To fit that in memory you need 28944 x 28944 x 8 bytes, which is over 6 GB of memory. You simply don't have enough memory on your machine.

Even on my laptop, with 16 GB of memory, I had to kill the calculation as it was taking a long time. That's a huge matrix you want to create. You may want to revisit your calculation.

[sasa]

thanks for your help Guillaume . Maybe it is the restriction of Matlab.

[Guillaume]

No, it's not a restriction of matlab. If you do want to create a 28944 x 28944 matrix, it will use over 6GB of memory regardless of the program.

You could halve the memory usage by switching to single instead of double but it's still more memory than you have.

If you do want to calculate an array of that size, your only option is to calculate part of it, save it to disk, calculate another part, save it to disk, and so on.

[sasa]

Thanks alot Guillaume.