How to hide a variable from workspace in matlab

Question

Is there an undocumented way to render a variable 'invisible' in matlab such that it still exists but does not show up in the workspace list?

Answer 1

The only way I can think of is to actually use a function, in the same way as MATLAB defines pi, i, and j. For example:

function value = e
   value = 2.718;
end

There will be no variable named e listed in your workspace, but you can use it as though there were:

a = e.^2;

Technically, it's only "invisible" in the sense that functions like who and whos don't list it as a variable, but the function will still have to exist on your MATLAB path and can still be called by any other script or function.

Answer 2

One thing you can do is have global variables. An interesting property of these is that even when you clear the workspace they still exist in memory unless you clear global variables specifically. An example is below.

global hidden_var
hidden_var = 1;
clear
global hidden_var
hidden_var

I'm still not entirely sure why you would even want the feature but this is a way that you can "hide" variables from the workspace.