// CALCULATE VARIANCE OVER LAST N POINTS 

Ni    =    1000;
Nj    =    10;
Nk    =    10;

A     =    rand(Ni,Nj,Nk);    



tic();
t0    =    getdate();

N   =    10;           

for k=1:Nk,
    for j=1:Nj,
       for i=N:Ni,                           
           B(i-(N-1),j,k)   = (    mean(A(i-(N-1):i,j,k))    )^2;        // Meansquare over last N points                      
           C(i-(N-1),j,k)   =     mean( A(i-(N-1):i,j,k).^2  )  ;                 
           D(i-(N-1),j,k)   =  B(i-(N-1),j,k) - C(i-(N-1),j,k)  ;        // Variance of over last N points
       end
    end
end

t1    =    getdate();   
toc();

dt    =    etime(t1,t0);
disp(dt);