小结、作业与预告

1. 步数:N_step = O(T·ε^{−1/p});二阶格式 M = O(T/√ε)

2. 常系数解:u(t) = e^{At}·u₀;酉 ⟺ A = iH(H = H†)

3. Magnus:Ω = ∫₀ᵗA + ½∫₀ᵗds∫₀ˢ[A(s),A(τ)]dτ + O(t³)

4. Schrödingerization:𝒦 = H_R⊗P − H_I⊗I;恢复 e^η·Φ = e^{At}·u₀

5. Duhamel:u(t) = e^{At}·u₀ + ∫₀ᵗe^{A(t−s)}b(s)ds;常值右端加 A⁻¹(e^{At}−I)·b₀

6. 堆叠系统:ρ = (1+ha/2)/(1−ha/2) ≈ e^{ha};κ(L) = Θ(M)(稳定)

7. 历史态:P(M) = ‖u(T)‖²/Σ_j‖u_j‖²

8. Carleman:d v_k/dt = k(a·v_k + b·v_{k+1} + c·v_{k−1});K = O(log(1/ε)/log(1/R))

9. 热方程:û_k(t) = e^{−αk²t}·û_k(0)(例 e^{−0.4} ≈ 0.67)

10. 波方程:M = [[0,B],[−B,0]]、M† = −M;能量 ‖Bu‖²+‖v‖² 守恒

11. Poisson:λ_k = (4/h²)·sin²(kπ/(2(N+1)));κ = O(N²)(N = 9:λ₁ ≈ 9.79 vs π² ≈ 9.87)

12. 谱方法:û_k = ĝ_k/k²(k ≠ 0);QFT 链路无 κ

类型summary-homework(公式清单)