Out of memory error

Hi, When I'm trying to multiply a [112880x10] matrix with another matrix of [10x125000], I get an error message "Out of memory". Is there a way of getting around this problem (using special algorithms or similar)?

Answer 1

[Andreas Goser]

One double has 2 bytes.

So the 112880x10 matrix has 2257600 bytes. Fine 10x125000 -> 2500000 bytes. Also Fine

But multiplying should give a 112880x125000 matrix! That is 2.8220e+10 bytes == 26 Gigabytes! Nut sure if this works, but is definitely a challenge. Maybe you are happy with singles too? Also I assume you have a 64 Bit MATLAB on 64 bit OS? You might want to test with slightly smaller matrices where the limit is.

[Andreas Goser]

This test script with a tenth of the size runs 140s for me:

clc
size_B=12500; %125000
A=rand(112880,10);
B=rand(10,size_B);
tic
C=A*B;
toc
whos C

[nilsotto]

I was thinking about triangularization or something similar?!

[Walter Roberson]

Triangularization does not reduce the amount of memory required for the final matrix, and that is your problem rather than "working memory" to do the calculation in.