̅ − ℎ ∆ ̅ = − = = = ∆ ℎ = − ≪ 1 ⁄ ℎ ∆ 1 ℎ 2 2 2 ∆ = 1 − ∆ + 1 − 2 [Δ ∙ + 4(1 + ) + 1 (2 − ) ] 8 (1 + ) = = Δ = = = , , 3 3 2 1 11 22 12 33