title: Multiplying vector element by every other one
body: <p>Let's assume I have a vector </p>
  
  <pre><code>Vec[5] = {a1, a2, a3, a4, a5}
  </code></pre>
  
  <p>How can I make a method that multiplies:</p>
  
  <pre><code>a1*a2, a1*a3, a1*a4, a1*a5
  a2*a3, a2*a4, a2*a5
  a3*a4, a3*a5
  a4*a5
  </code></pre>
  
  <p>Thanks!</p>