arXiv:2607.28036cs.LGcs.NA2026-07

通过学习参数空间特征,加速非线性偏微分方程求解器的收敛。

Learning features from Newton's algorithm: a way to accelerate nonlinear parametrized PDE solvers

论文配图:Learning features from Newton's algorithm: a way to accelerate nonlinear parametrized PDE solvers
图 1 · 摘自论文原文
  • 利用预计算解和牛顿轨迹构建解特征与修正方向特征空间。
  • 对新参数用回归预测初值,再用小规模最小二乘法修正残差。
  • 方法轻度侵入,适用于大规模非线性问题,显著减少迭代次数和耗时。

已知牛顿法在初始猜测接近方程根时收敛更快。本文提出一种两阶段牛顿初值策略:通过参数空间采样和预计算解数据库学习特征。利用离散牛顿轨迹构建两个互补的降维空间——由收敛状态构建的解特征空间,以及由中间牛顿增量构建的修正方向特征空间。对于未见参数,先用回归模型预测近似解;第二步则采用基于GMRES的残差最小化方法计算修正项。该修正状态作为高保真牛顿法的初值,完成最终收敛。修正步骤计算成本低,仅需残差评估和小规模最小二乘求解。该方法一旦具备高保真残差场和脚本接口即为弱侵入式。数值实验在典型偏微分方程问题上显示,相比独立代理模型初始化,该策略实现可量化的加速,速度提升显著。该通用方法适用于广泛的大规模非线性问题。

原文摘要 · Abstract (English)

It is well known that Newton's method converges faster when the initial guess is closer to a root of a system of nonlinear equations. In this paper, a two-stage Newton initial guess strategy is proposed by learning features from a parameter-space sampling and a database of precomputed solutions. The method uses discrete Newton trajectories to construct two complementary reduced spaces: a solution feature space, built from converged states, and a corrective search direction feature space, built from intermediate Newton increments. For an unseen parameter, a regression model is used to predict a surrogate solution approximation. Then, in a second step, a residual-minimizing correction is computed using a dedicated GMRES-based approach. The resulting state is then used as an initial guess for the high-fidelity Newton method, which completes convergence. The corrective step is computationally inexpensive since it only requires residual evaluations and the solution of a small least-squares problem. The methodology is weakly intrusive once the high-fidelity residual fields and a script-based programming interface are available. This strategy reduces the number of Newton iterations and decreases the overall CPU time. Numerical experiments on representative PDE problems show quantifiable speedups compared with standalone surrogate initialization. Significant speedups are observed. This generic approach can be applied to a broad class of large-scale nonlinear problems.

偏微分方程牛顿法加速求解降维建模

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