def norm_l21(A, n_orient, copy=True):
 if (A.size == 0):
  return 0.0
 if copy:
  A = A.copy()
 return np.sum(np.sqrt(groups_norm2(A, n_orient)))

def norm_l21 ( A , n_orient , copy = True ) : if ( A . size == 0 ) : return 0.0 if copy : A = A . copy ( ) return np . sum ( np . sqrt ( groups_norm2 ( A , n_orient ) ) )
l21 norm .