Programming and Data Types

Making Efficient Use of Memory

This section discusses how to conserve memory and improve memory use. Topics include

• Memory Management Functions
• Ways to Conserve Memory
• "Out of Memory" Errors
• Platform-Specific Memory Topics

For more information on memory management, see Technical Note 1106: "Memory Management Guide", at the following URL:

http://www.mathworks.com/support/tech-notes/1100/1106.shtml

Memory Management Functions

The following functions can help you to manage memory use in MATLAB:

• whos shows how much memory has been allocated for variables in the workspace.
• pack saves existing variables to disk, and then reloads them contiguously. This reduces the chances of running into problems due to memory fragmentation.

• See Compressing Data in Memory.

• clear removes variables from memory. One way to increase the amount of available memory is to periodically clear variables from memory that you no longer need.
• save selectively stores variables to the disk. This is a useful technique when you are working with large amounts of data. Save data to the disk periodically, and then clear the saved data from memory.
• load reloads a data file saved with the save function.
• quit exits MATLAB and returns all allocated memory to the system. This can be useful on UNIX systems as UNIX does not free up memory allocated to an application (e.g., MATLAB) until the application exits.

• See Freeing Cleared Memory on UNIX.

Note    save and load are faster than the MATLAB low-level file I/O routines. save and load have been optimized to run faster and reduce memory fragmentation.

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Ways to Conserve Memory