docs: public static void householder(double gamma,
                                     DMatrixD1 u ,
                                     DMatrixD1 x , DMatrixD1 y )
      {
          int n = u.getNumElements();
  
          double sum = 0;
          for( int i = 0; i < n; i++ ) {
              sum += u.get(i)*x.get(i);
          }
          for( int i = 0; i < n; i++ ) {
              y.set( i , x.get(i) + gamma*u.get(i)*sum);
          }
      }