MATLAB: How to speed up calculations

code optimizationcomputation time

Hello, I am running a code creating and then analyzing large arrays (let's say consisting 15M data). My problem is that, when the code is running, I observe that the cpu usage is at 25% and RAM usge is about 410 Mb. My computer has 4 gb ram and is 2.9 Ghz. How can I make matlab to use more cpu and ram in order to speed up the calculations. (now the calculation time is about 2 hours). ps: I pre allocated every array, also changed the virtual memory size and swap size and tried to switch 3gb from command prompt with BCDEdit /set increaseuserva 3072 command. Any help would be appreciated.

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You have made a lot of things already about hardware enhancement like setting the 3GB Switch. You should use the profiler of MATLAB to find bottlenecks if any.

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MATLAB: Increasing matlab memory size

"Memory used by MATLAB" is internal memory used by the MATLAB interpreter itself, as opposed to memory allocated to user variables. Low is good for "Memory used by MATLAB" as the memory used by MATLAB itself is not available to user variables.

With your system set up as it is, you could use individual arrays up to 1 gigabyte, and more than 2 gigabytes total between all of your arrays.

To speed up MATLAB, what you should do is reduce the Swap Space you have allocated to the system. Especially if you set the swap space to 0, everything in the system will run in RAM, which would be faster than going to the hard disk. Of course if you do that, then you will only be able to use much smaller arrays than you can use now, since the operating system and other programs will be using up some of your 3 Gb physical RAM.

What would really be recommended is to add more physical memory to your system. You might need to also switch to the 64 bit of MATLAB to take best advantage of the extra memory. But if you are using Student Version then I seem to recall there is only the 32 bit version of that on MS Windows or Linux.

MATLAB: Increase using all RAM

More RAM does not help you to do anything if you have a small problem that is not bound by the amount of RAM. For example, suppose you wish to add two numbers.

x = 1 + 2;

How much extra RAM you have has absolutely NOTHING to do with speed of that computation. It is the processor that makes a difference here, not the amount of RAM available to it. (Yes, not all RAM is the same in terms of access time, but that was not the question posed.)

In your case, it appears that this extra memory you have was not needed, any more than it would be for the simple case I show above.

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MATLAB: Increasing matlab memory size

MATLAB: Increase using all RAM

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