MATLAB: Append rows to same .mat file (without replacing)

.mat file

What is the syntax for appending values to a existing .mat file? When I use -append, I end up replacing the values!
Example: %% code updated %%
   for col = 1:10
    out = zeros(1,1000000); %reset out to zero vector
    x=randn(1,100000);
    out(col,:)=x.^2;
    if col == 1
    filename='z.mat';
    save(filename,'out','-v7.3'); % Write to MAT file
    else
    save(filename,'out','-v7.3','-append');
    end
 end
After running the above code, I have a .mat file out(10×100000) but it contains only the saved values of last column (rest zeros). That is, each time I zero the out variable, the same is written to file also. I want to save all the values without holding them in variable out (due to memory constrains) . How can I do this?
What am I missing? please locate in my code.

Best Answer

From the documentation on save:
   '-append': Add data to an existing file.
Does your file exist?
      if col == 1
          save(filename,'out','-v7.3');
      else
          save(filename,'out','-v7.3','-append');
      end
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