arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2010.01807math.NAcs.NA
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对数倒数近似和平面PDE求解器

Reciprocal-log approximation and planar PDE solvers

Yuji Nakatsukasa, Lloyd N. Trefethen

摘要:

这篇文章是关于逼近论和偏微分方程(PDE)的数值解的。首先,我们介绍了{ \em倒数对数}或{ \em对数闪电逼近}的概念,具有分支点奇点的解析函数在点$\{z_k\}$由形式为$g(z) = \sum_k c_k /(\log(z-z_k) - s_k)$的函数,其中有$N$极点潜在地沿黎曼曲面分布。我们证明了最佳倒数对数近似的误差相对于$N$呈指数下降,并且指数或近指数收敛(即,速率为$O(\exp(-C N / \log N))$)也适用于具有通过边界上的线性最小二乘拟合构造的预先指定的奇点的近最佳逼近。然后,我们应用这些结果来获得一个“对数闪电法”的数值解拉普拉斯和相关的偏微分方程在二维区域的角奇异性。与基于有理函数的原始闪电方法的根指数收敛相比,该方法的收敛性是近指数的。

英文摘要:

This article is about both approximation theory and the numerical solution of partial differential equations (PDEs). First we introduce the notion of {\em reciprocal-log} or {\em log-lightning approximation} of analytic functions with branch point singularities at points $\{z_k\}$ by functions of the form $g(z) = \sum_k c_k /(\log(z-z_k) - s_k)$, which have $N$ poles potentially distributed along a Riemann surface. We prove that the errors of best reciprocal-log approximations decrease exponentially with respect to $N$ and that exponential or near-exponential convergence (i.e., at a rate $O(\exp(-C N / \log N))$) also holds for near-best approximations with preassigned singularities constructed by linear least-squares fitting on the boundary. We then apply these results to derive a "log-lightning method" for numerical solution of Laplace and related PDEs in two-dimensional domains with corner singularities. The convergence is near-exponential, in contrast to the root-exponential convergence for the original lightning methods based on rational functions.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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