title: How to use ‘not equal to’ inequality constraint in fmincon?
body: <p>How can I set the constraints for the solution (<code>x1</code>,<code>x2</code>), so that <code>x1 ~= x2</code> (<code>x1</code> is not <code>x2</code>) in the MATLAB function <code>fmincon</code>?<br>
  In numerical sense: <code>x1</code> should not get close to <code>x2</code>.</p>