MATLAB Error:Out of Memory - matlab

Question

So I'm trying to perform STFT on a piano recording using matlab, but I get the following error.
Warning: Input arguments must be scalar.
In test3 at 35
??? Error using ==> zeros
Out of memory. Type HELP MEMORY for your options.
Error in ==> test3 at 35
song = cat(1,song,zeros(n_of_padding,1));
The coding I've used is taken from a sample code found on the net.
clc;
clear all;
[song,FS] = wavread('c scale fast.wav');
song = sum(song,2);
song = song/max(abs(song));
wTime = 0.05;
ZP_exp = 1;
P_OL = 50;
% Number of STFT samples per STFT slice
N_window = floor(wTime*FS);
% Number of overlapping points
window_overlap = floor(N_window*(P_OL/100));
wTime = N_window/FS;
%size checking
%make sure there are integer number of windows if not zero pad until they are
L = size(song);
%determine the number of times-1 the overlapping window will fit the song length
N_of_windows = floor(L - N_window/(N_window - window_overlap));
%determine the remainder
N_of_points_left = L - (N_window + N_of_windows*(N_window - window_overlap));
%Calculate the number of points to zero pad
n_of_padding = (N_window - window_overlap) - N_of_points_left;
%append the zeros to the end of the song
song = cat(1,song,zeros(n_of_padding,1));
clear n_of_windows n_of_points_left n_of_padding
n_of_windows = floor((L - N_window)/(N_window - window_overlap))+1;
windowing = hamming(N_window);
N_padding = 2^(nextpow2(N_window)+ZP_exp);
parfor k = 1:N_of_windows
starting = (k-1)*(N_window -window_overlap) +1;
ending = starting+N_window-1;
%Define the Time of the window, i.e., the center of window
times(k) = (starting + ceil(N_window/2))/Fs;
%apply windowing function
frame_sample = music(starting:ending).*windowing;
%take FFT of sample and apply zero padding
F_trans = fft(frame_sample,N_padding);
%store FFT data for later
STFT_out(:,k) = F_trans;
end

Answer 1

Based on some assumptions I would reason that:
- n_of_padding should be smaller than N_window
- N_window is much smaller FS
- Fs is not too high (frequency of your sound, so should not exceed a few thousand?!)
- Your zeros matrix will not be huge
This should mean that the problem is not that you are creating a too large matrix, but that you already filled up the memory before this call.
How to deal with this?
First type dbstop if error
Run your code
When it stops check all variable sizes to see where the space has gone.
If you don't see anything strange (and the big storage is really needed) then you may be able to process your song in parts.

Answer 2

In line 35 you are trying to make an array that exceeds your available memory. Note that a 1 by n array of zeros alone, is n*8 bytes in size. This means if you make such an array, call it x, and check it with whos('x'), like:
x = zeros(10000,1);
whos('x');
You will likely find that x is 80000 bytes. Maybe by adding such an array to your song variable is adding the last bytes that breaks the memory-camel's back. Using and whos('variableName') take whatever the size of song is before line 35, separately add the size of zeros(n_of_padding,1), convert that to MB, and see if it exceeds your maximum possible memory given by help memory.

Answer 3

The most common implication of Out of memory errors on Matlab is that it is unable to allocate memory due to the lack of a contiguous block. This article explains the various reasons that can cause an Out of memory error on MATLAB.
The Out of memory error often points to a faulty implementation of code that expands matrices on the fly (concatenating, out-of-range indexing). In such scenarios, MATLAB creates a copy in memory i.e memory twice the size of the matrix is consumed with each such occurrence.
On Windows this problem can be alleviated to some extent by passing the /3GB /USERVA=3030 switch during boot as explained here. This enables additional virtual memory to be addressed by the application(MATLAB in this case).