Programming

Resolving "Out of Memory" Errors

MATLAB generates an Out of Memory message whenever it requests a segment of memory from the operating system that is larger than what is currently available. This section covers the following topics providing suggestions on how to resolve such errors:

• General Suggestions for Reclaiming Memory
• Compressing Data in Memory
• Increasing System Swap Space
• Freeing Up System Resources on Windows Systems
• Reloading Variables on UNIX Systems

General Suggestions for Reclaiming Memory

When you see the Out of Memory message, use any of the techniques discussed under Using Memory Efficiently to help optimize the available memory. If the Out of Memory message still appears, you can try any of the following:

• Compress data to reduce memory fragmentation
• If possible, break large matrices into several smaller matrices so that less memory is used at any one time.
• If possible, reduce the size of your data.
• Make sure that there are no external constraints on the memory accessible to MATLAB. (On UNIX systems, use the limit command to check).
• Increase the size of the swap file. We recommend that your machine be configured with twice as much swap space as you have RAM. See Increasing System Swap Space, below.
• Add more memory to the system.

Compressing Data in Memory

Since MATLAB uses a heap method of memory management, extended MATLAB sessions may cause memory to become fragmented. When memory is fragmented, there may be plenty of free space, but not enough contiguous memory to store a new large variable. If you get the Out of Memory message from MATLAB, the pack function may be able to compress some of your data in memory, thus freeing up larger contiguous blocks.

Note    Because of time considerations, you should not use pack within loops or M-file functions.

Strategies for Efficient Use of Memory

Increasing System Swap Space

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