def METHOD_NAME(self, p=None):
    """
    Notes
    -----
    对基函数求一阶导后非零项的编号，及系数
    """
    p = self.p if p is None else p
    index = multi_index_matrix2d(p)
    x, = np.nonzero(index[:, 1] > 0) # 关于 x 求导非零的缩放单项式编号
    y, = np.nonzero(index[:, 2] > 0) # 关于 y 求导非零的缩放单项式编号
    return {'x':(x, index[x, 1]),
            'y':(y, index[y, 2]),
            }