title: How to insert a column/row of ones into a matrix?
body: <p>Suppose that we have  a 3x3 matrix like </p>
  
  <pre><code>b = 2 * eye(3);
  ans =
  
  2   0   0
  0   2   0
  0   0   2
  </code></pre>
  
  <p>and I want to a 3x4 matrix like </p>
  
  <pre><code>1   2   0   0
  1   0   2   0
  1   0   0   2
  </code></pre>
  
  <p>What is the best way to get it? </p>