def METHOD_NAME(i):
    """ compute single H[:,i] """
    # optimize alpha using qp solver from cvxopt
    FA = base.matrix(np.float64(np.dot(-self.W.T, self.data[:,i])))
    al = solvers.qp(HA, FA, INQa, INQb, EQa, EQb)
    self.H[:,i] = np.array(al['x']).reshape((1, self._num_bases))