title: Ruby mathematic gem
body: <p>does anybody know if there is a good gem for mathematic / geometric operations? I need some of this things:</p>
  
  <ul>
  <li>Dot product</li>
  <li>Cross product</li>
  <li>Angle between vectors</li>
  <li>Matrix</li>
  <li>Surface normale</li>
  <li>Vector calculations (add, substract...)</li>
  <li>Singular Value Decomposition</li>
  </ul>
  
  <p>thx,
  tux</p>