I'm using a matlab script to create and store a large matrix of floating point numbers. When I tried running this program on my personal laptop, the program ended hours later with the message 'out of memory'. Supposedly, Matlab has a limit for the maximum-sized array it can store, which makes sense.
My question is: how to store large matrix in matlab? Specifically, I'm using a 64-bit linux OS, and I need to store a 5-6 GB matrix.
I am not an expert in this, but as I understand it the most simple solution would be to get more RAM. However, you could try to check the available memory at the time of the error with
dbstop if error
memory
This should tell you how much Memory is available for Matlab, how much is currently used and how large your biggest array can be. If you exceed this I don't think there is a software solution for that besides storing the data in multiple smaller files.
If you get the "Out of memory: Java Heap Space" error you can increase the memory which is available for Java under (Home -> Preferences -> General -> Java Heap Memory)
Also check if your array side is limited to a certain percentage of your available memory under (Home -> Preferences -> Workspace -> MATLAB array size limit) and set it to 100%.
Similar question in Matlab forum
Related
I have to integrate an ODE of 8 variable in matlab. My simulation time is 5e9 with a time step of 0.1. But it shows memory error. I am working with i7 core ,2.6Ghz CPU with 8GB RAM. How can I simulate ODEs for a large time samples?
Assuming you're working on 64 Bit version of MATLAB you might want to let MATLAB squeeze the memory to the edge using the Preferences -> MATLAB -> Workspace -> MATLAB Array Size Limit.
If you are getting this erro because you really mximized the memory in the system do the following:
Make sure you're using 64 Bit OS and 64 Bit version of MATLAB.
Before you call the ODE function, clear manually (using the clear() function) variables you don't need any more (Or can recreate once the function finishes).
Increase the swap file of your system. It will help with larger memory consumption but might make things much slower.
You can find more tips and tricks in Resolve "Out of Memory" Errors and memory().
I am suffering from the out of memory problem in mablab.
Is is possible to build a large memory system for matlab(e.g. 64GB ram)?
If yes, what do I need?
#Itamar gives good advice about how MATLAB requires contiguous memory to store arrays, and about good practices in memory management such as chunking your data. In particular, the technical note on memory management that he links to is a great resource. However much memory your machine has, these are always sensible things to do.
Nevertheless, there are many applications of MATLAB that will never be solved by these tips, as the datasets are just too large; and it is also clearly true that having a machine with much more RAM can address these issues.
(By the way, it's also sometimes the case that it's cheaper to just buy a new machine with more RAM than it is to pay the MATLAB developer to make all the memory optimizations they could - but that's for you to decide).
It's not difficult to access large amounts of memory with MATLAB. If you have a Windows or Linux machine with 64GB (or more) - it will obviously need to be running a 64-bit OS - MATLAB will be able to access it. I've come across plenty of MATLAB users who are doing this. If you know what you're doing you can build your own machine, or nowadays you can just buy a machine that size of the shelf from Dell.
Another option (depending on your application) would be to look into getting a small cluster, and using Parallel Computing Toolbox together with MATLAB Distributed Computing Server.
When you try to allocate an array in Matlab, Matlab must have enough contiguous memory the size of the array, and if not enough contiguous memory is available, you will get out of memory error, no matter how much RAM you have on your computer.
From my experience, the solution will not come from dealing directly with memory-related properties of your hardware, but from writing your code in a way that prevents allocation of too large arrays (cutting data to chunks, etc.). If you can describe your code and the task you try to solve, it might be possible to guide you in that direction.
You can read more here:http://www.mathworks.com/support/tech-notes/1100/1106.html
This may seem like a little simple question to some, surely, but I haven't been able to find a direct answer online.
How much memory does MATLAB needs for a single double value (from my undestanding it is his default data type) and taking that into account what would be the largest amount of memory it could allocate on a PC (with more than enough RAM)? Are there any restrictions in that view?
This is in view that on my faculty we're thinking about transferring some programs which have been written in C to MATLAB, but are concerned about such issues.
'For floating-point numbers, MATLAB uses 4 or 8 bytes for single and double types.' <- quote from here. The memory model of Matlab is quite flexible. Five years ago I was inverting 1,000,000 by 1,000,000 matrices on a cluster using an add-on package Star-p which I guess was recently acquired by Microsoft.
As long as you're on a 64bit box, you can access 2^64 bytes of memory <- Matlab is simply limited by the physical limitations of your box, though as noted above, there are solutions to create a shared memory pool across a cluster of computers within a single Matlab environment.
See here and look up what the max size is for your machine specs. For Windows XP 32 bit, the total workspace size (max) is about 1700 MB and the largest matrix size is about 1200 MB.
I want to calculate 2 covariance matrices with size (10304,1034) and matlab creates the first one but when it runs the second command, this error occurs:
>> j=ones(10000,10000);
>> jj=ones(10000,10000);
??? Out of memory. Type HELP MEMORY for your options.
My laptop's RAM is 2GB, but it still has 1 GB free. I am using Windows 7 and 32-bit MATLAB 2009b.
How can I resolve this error?
A 10k-by-10k array of doubles uses 1e8*8 bytes, which corresponds to 800MB. MATLAB needs these 800MB to be contiguous. Most likely, your 1GB free memory is a little fragmented, so MATLAB cannot fit the new array into RAM.
Use the command MEMORY to find out the maximum variable size that MATLAB can handle at a given moment.
Try to use sparse matrices, in that case MATLAB doesn't allocate the entire space.
Try any of these two options little bit increase in memory allocated for matlab.exe processing.
1- Give higher priority to Matlab.exe task. You can do that by going to task manager, Processes tab, right click the Matlab.exe Task, select priority and set it to higher priority (say real time), this tells Windows to allocate more resources to this process.
2- Increase the page file size of your applications in general. You can do this by right clicking MyComputer ->properties->Advanced System Settings ->Advanced-> Performance->Virtual Memory (change..). Then the tick from the Automatic .... and set the initial and maximum page size to say 10000 MB.
Go to Matlab-->file-->Preferences-->general-->Java heap memory--> and increase the level.. This solved my problem
When I run a sample script in MATLAB, it says:
Out of memory. Type HELP MEMORY for your options.
When I type "memory", it reports:
Maximum possible array: 156 MB (1.638e+008 bytes) *
Memory available for all arrays: 740 MB (7.756e+008 bytes) **
Memory used by MATLAB: 1054 MB (1.105e+009 bytes)
Physical Memory (RAM): 3070 MB (3.219e+009 bytes)
* Limited by contiguous virtual address space available.
** Limited by virtual address space available.
Is there any way to get around this error? I'm using Windows XP x32 with MATLAB 2009a.
pack does a memory defragmentation. It might help you a bit as far as the contiguous memory available.
Remember, when MATLAB says it's out of memory, it means it's out of contiguous memory, so rebooting or restarting MATLAB may work.
But, I'd recommend optimizing your code and identifying how you're eating up so much memory. It could be an ill-designed recursive loop, or a bad indexing function (using doubles instead of logicals to index a huge matrix).
I practically lived with memory errors for a while since I was dealing with huge datasets, but there's always a workaround, ask specific questions and you'll be surprised.
Problem fixed.
Under Windows XP x32, I managed to almost double the amount of memory available to MATLAB by editing boot.ini to add the switch /3GB /USERVA=3030
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect /3GB /USERVA=3030
Together with reducing our array sizes, this completely fixed the problem :)
I could have also fixed the problem by upgrading to Windows x64 or Windows 7 x64. This act also doubles the amount of memory available to MATLAB, even if you stick with MATLAB x32 and don't upgrade to MATLAB x64. Windows x64 is just far more memory efficient, even with systems that only have 4 GB of physical RAM installed.
Try this, it works well for me.
Go to Home -> Preference icon -> General -> Java Heap Memory -> Allocate what size of memory you want
In Preference window, go to "Workspace" (out of Java heap memory level) -> See "Matlab Array size limit"
Make sure uncheck the 'Limit the maximum array size to a percentage of RAM'. Because you want to extend memory
so we don't need this feature.
Done.
What are you attempting to allocate when it runs out of memory (OOM)? Do you have code to reproduce? A wide range of problems can cause out of memory errors.
To diagnose, use "dbstop if all error" to set a breakpoint on errors. The out of memory will trigger this, and you can use dbup, dbdown, and whos() to see what's consuming memory. Often an OOM is caused by a bad array size or index calculation, not just by big data structures. E.g. this will trigger an OOM in pretty much any 32-bit MATLAB.
>> x = 1;
>> x(2^30) = 2
??? Out of memory. Type HELP MEMORY for your options.
I faced a similar error while running an (old) C file in MATLAB using mex.
I found my solution at this issue on GitLab.
First, uncheck the option "Limit the maximum Array Size to a % of RAM" located under Preferences -> Workspace, as also indicated in this earlier answer.
Once applied, run your C file in the command window using
mex filename.c -compatibleArrayDims