How can I replace every element of a matrix with a special character to hide the element

I have a nxn matrix and want to hide the elements and replace them with a special character

Example

1 2 3
4 5 6
7 8 9

is now

* * *
* * *
* * *

[Walter Roberson]

"hide them" in what context?

Answer 1

[Rick Rosson]

   x = magic(3);
   y = repmat('*',size(x));
   disp(y);

Answer 2

[Rick Rosson]

   x = magic(3);
   x(x<7) = NaN;
   disp(x);

Answer 3

[Image Analyst]

Try this, using fprintf():

m = [...
  1 2 3
4 5 6
7 8 9]
[rows, columns] = size(m);
for row = 1 : rows
  for col = 1 : columns
    fprintf('* ');
  end
  fprintf('\n');
end

and this.