Cannot clear a global variable from inside a function

[oxyopes]

Hi friends, look that:

global x=[1 2 3];

function mmm
     global x
     printf("the value of x is %d\n", x)
     clear x; global x
endfunction

mmm
clear x; global x   % clears x outside mmm
x(1)=2;
mmm


The second run of mmm should show only x(1),
since the others were cleared. But no, they aren't cleared.
The manual doesnt mention that. Any tip?

Thanks in advance ...