MATLAB: Faster way to initilize arrays via empty matrix multiplication

initializationMATLABmatrixmatrix manipulationperformance

I've stumbled upon the weird way (in my view) that Matlab is dealing with empty matrices. For example, if two empty matrices are multiplied the result is:
    zeros(3,0)*zeros(0,3)
    ans =
     0     0     0
     0     0     0
     0     0     0
Now, this already took me by surprise, however, a quick search got me to the link http://www.mathworks.com/help/matlab/math/empty-matrices-scalars-and-vectors.html , and I got an explanation of the somewhat twisted logic of why this is happening.
However, nothing prepared me for the following observation. I asked myself, how efficient is this type of multiplication vs just using zeros(n) function, say for the purpose of initialization? I've used timeit to answer this:
    f=@() zeros(1000)
    timeit(f)
    ans =
        0.0033
vs:
    g=@() zeros(1000,0)*zeros(0,1000)
    timeit(g)
    ans =
        9.2048e-06
Both have the same outcome of 1000×1000 matrix of zeros of class `double`, but the empty matrix multiplication one is ~350 times faster! (a similar result happens using `tic` and `toc` and a loop)
How can this be? are `timeit` or `tic,toc` bluffing or have I found a faster way to initialize matrices?
(this was done with matlab 2012a, on a win7-64 machine, intel-i5 650 3.2Ghz…)
I have looked more carefully into this peculiarity, and tested on 2 different computers (same matlab ver though 2012a) a code that examine the run time vs the size of matrix n. This is what I get:
The code to generate this used timeit as before, but a loop with tic and toc will look the same. So, for small sizes, zeros(n) is comparable. However, around n=400 there is a jump in performance for the empty matrix multiplication. The code I've used to generate that plot was:
    n=unique(round(logspace(0,4,200)));
    for k=1:length(n)
        f=@() zeros(n(k));
        t1(k)=timeit(f);
        g=@() zeros(n(k),0)*zeros(0,n(k));
        t2(k)=timeit(g);
    end
    loglog(n,t1,'b',n,t2,'r');
    legend('zeros(n)','zeros(n,0)*zeros(0,n)',2);
    xlabel('matrix size (n)'); ylabel('time [sec]');
Are any of you seeing anything similar?

Best Answer

... got me to the link above...
I cannot find the link you refer to.
.
The Windows task manager shows that
    Z = zeros(1000,0)*zeros(0,1000);
doesn't allocate memory (R2012a, 64bit, Win7). Or rather the task manager doesn't show any allocation of memory for that assignment.
.
ADDED
I learned two things. There is a small speed advantage of using this way of memory allocation. While experimenting I made it necessary to restart the computer and I lost my desktop configuration.
    N = 1e4;
    clear z1
    tic
    z1 = zeros( N ); 
    for cc = 1 : N
        z1(:,cc)=cc;
    end
    toc
    clear z0
    tic
    z0 = zeros(N,0)*zeros(0,N);
    for cc = 1 : N
        z0(:,cc)=cc;
    end
    toc
    Elapsed time is 0.686084 seconds.
    Elapsed time is 0.532437 seconds.
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