append rows to same .mat file (without replacing)

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(10x100000) 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.

Answer 1

[Geoff]

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

[zozo]

thank you @Geoff

[zozo]

@geoff: There is still a problem. (please have a look at the updated question above)