code: public T getEigenVector( int index ) {
          Matrix v = eig.getEigenVector(index);
          if( v == null )
              return null;
          return (T)SimpleMatrix.wrap(v);
      }
docs: <p>
  Used to retrieve real valued eigenvectors.  If an eigenvector is associated with a complex eigenvalue
  then null is returned instead.
  </p>
  
  @param index Index of the eigenvalue eigenvector pair.
  @return If the associated eigenvalue is real then an eigenvector is returned, null otherwise.