def METHOD_NAME(self):
    p = 2
    ldof = (p+1)*(p+2)//2
    idx = np.arange(0, ldof)
    idx0 = np.floor((-1 + np.sqrt(1 + 8*idx))/2)
    multiIndex = np.zeros((ldof, 3), dtype=np.int8)
    multiIndex[:, 2] = idx - idx0*(idx0 + 1)/2
    multiIndex[:, 1] = idx0 - multiIndex[:, 2]
    multiIndex[:, 0] = p - multiIndex[:, 1] - multiIndex[:, 2]
    return multiIndex