title: How to build a ortoghonal basis from a vector?
body: <p>anybody know how I can build a orthogonal base using only a vector? I have a vector in the form v1 = [a b -a -b]', where 'a' and 'b' are real numbers. I did try build in the "adhoc way" but, nothing, I only got two orthogonal vectors:</p>
  
  <p>v1 = [a  b -a -b]'
  v2 = [a -b  a -b]'</p>
  
  <p>I need more two vectors to complete the orthogonal basis {v1, v2, v3, v4}. Anybody can help me?</p>
  
  <p>Thanks...</p>