首页 > 最新文献

Acta Numerica最新文献

英文 中文
Modelling and computation of liquid crystals 液晶的建模与计算
IF 14.2 1区 数学 Q1 MATHEMATICS Pub Date : 2021-04-06 DOI: 10.1017/S0962492921000088
Wen Wang, Lei Zhang, Pingwen Zhang
Liquid crystals are a type of soft matter that is intermediate between crystalline solids and isotropic fluids. The study of liquid crystals has made tremendous progress over the past four decades, which is of great importance for fundamental scientific research and has widespread applications in industry. In this paper we review the mathematical models and their connections to liquid crystals, and survey the developments of numerical methods for finding rich configurations of liquid crystals.
液晶是介于结晶固体和各向同性流体之间的一种软物质。近四十年来,液晶研究取得了巨大进展,对基础科学研究具有重要意义,在工业上有着广泛的应用。在本文中,我们回顾了数学模型及其与液晶的联系,并综述了寻找丰富液晶构型的数值方法的发展。
{"title":"Modelling and computation of liquid crystals","authors":"Wen Wang, Lei Zhang, Pingwen Zhang","doi":"10.1017/S0962492921000088","DOIUrl":"https://doi.org/10.1017/S0962492921000088","url":null,"abstract":"Liquid crystals are a type of soft matter that is intermediate between crystalline solids and isotropic fluids. The study of liquid crystals has made tremendous progress over the past four decades, which is of great importance for fundamental scientific research and has widespread applications in industry. In this paper we review the mathematical models and their connections to liquid crystals, and survey the developments of numerical methods for finding rich configurations of liquid crystals.","PeriodicalId":48863,"journal":{"name":"Acta Numerica","volume":"30 1","pages":"765 - 851"},"PeriodicalIF":14.2,"publicationDate":"2021-04-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49450682","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 34
Deep learning: a statistical viewpoint 深度学习:统计学观点
IF 14.2 1区 数学 Q1 MATHEMATICS Pub Date : 2021-03-16 DOI: 10.1017/S0962492921000027
P. Bartlett, A. Montanari, A. Rakhlin
The remarkable practical success of deep learning has revealed some major surprises from a theoretical perspective. In particular, simple gradient methods easily find near-optimal solutions to non-convex optimization problems, and despite giving a near-perfect fit to training data without any explicit effort to control model complexity, these methods exhibit excellent predictive accuracy. We conjecture that specific principles underlie these phenomena: that overparametrization allows gradient methods to find interpolating solutions, that these methods implicitly impose regularization, and that overparametrization leads to benign overfitting, that is, accurate predictions despite overfitting training data. In this article, we survey recent progress in statistical learning theory that provides examples illustrating these principles in simpler settings. We first review classical uniform convergence results and why they fall short of explaining aspects of the behaviour of deep learning methods. We give examples of implicit regularization in simple settings, where gradient methods lead to minimal norm functions that perfectly fit the training data. Then we review prediction methods that exhibit benign overfitting, focusing on regression problems with quadratic loss. For these methods, we can decompose the prediction rule into a simple component that is useful for prediction and a spiky component that is useful for overfitting but, in a favourable setting, does not harm prediction accuracy. We focus specifically on the linear regime for neural networks, where the network can be approximated by a linear model. In this regime, we demonstrate the success of gradient flow, and we consider benign overfitting with two-layer networks, giving an exact asymptotic analysis that precisely demonstrates the impact of overparametrization. We conclude by highlighting the key challenges that arise in extending these insights to realistic deep learning settings.
深度学习的显著实践成功从理论角度揭示了一些重大惊喜。特别是,简单的梯度方法很容易找到非凸优化问题的近似最优解,尽管在没有任何明确的控制模型复杂性的努力的情况下对训练数据给出了近似完美的拟合,但这些方法表现出了优异的预测准确性。我们推测这些现象背后的具体原理是:过帧化允许梯度方法找到插值解,这些方法隐含地施加正则化,并且过帧化导致良性过拟合,即,尽管训练数据过拟合,但仍能准确预测。在这篇文章中,我们调查了统计学习理论的最新进展,并提供了在更简单的环境中说明这些原则的例子。我们首先回顾了经典的一致收敛结果,以及为什么它们不能解释深度学习方法行为的各个方面。我们给出了在简单设置中的隐式正则化的例子,其中梯度方法导致完美拟合训练数据的最小范数函数。然后,我们回顾了表现出良性过拟合的预测方法,重点关注具有二次损失的回归问题。对于这些方法,我们可以将预测规则分解为对预测有用的简单分量和对过拟合有用的尖峰分量,但在有利的设置下,不会损害预测精度。我们特别关注神经网络的线性状态,其中网络可以通过线性模型来近似。在这种情况下,我们证明了梯度流的成功,并考虑了两层网络的良性过拟合,给出了精确的渐近分析,精确地证明了过帧化的影响。最后,我们强调了将这些见解扩展到现实的深度学习环境中所面临的关键挑战。
{"title":"Deep learning: a statistical viewpoint","authors":"P. Bartlett, A. Montanari, A. Rakhlin","doi":"10.1017/S0962492921000027","DOIUrl":"https://doi.org/10.1017/S0962492921000027","url":null,"abstract":"The remarkable practical success of deep learning has revealed some major surprises from a theoretical perspective. In particular, simple gradient methods easily find near-optimal solutions to non-convex optimization problems, and despite giving a near-perfect fit to training data without any explicit effort to control model complexity, these methods exhibit excellent predictive accuracy. We conjecture that specific principles underlie these phenomena: that overparametrization allows gradient methods to find interpolating solutions, that these methods implicitly impose regularization, and that overparametrization leads to benign overfitting, that is, accurate predictions despite overfitting training data. In this article, we survey recent progress in statistical learning theory that provides examples illustrating these principles in simpler settings. We first review classical uniform convergence results and why they fall short of explaining aspects of the behaviour of deep learning methods. We give examples of implicit regularization in simple settings, where gradient methods lead to minimal norm functions that perfectly fit the training data. Then we review prediction methods that exhibit benign overfitting, focusing on regression problems with quadratic loss. For these methods, we can decompose the prediction rule into a simple component that is useful for prediction and a spiky component that is useful for overfitting but, in a favourable setting, does not harm prediction accuracy. We focus specifically on the linear regime for neural networks, where the network can be approximated by a linear model. In this regime, we demonstrate the success of gradient flow, and we consider benign overfitting with two-layer networks, giving an exact asymptotic analysis that precisely demonstrates the impact of overparametrization. We conclude by highlighting the key challenges that arise in extending these insights to realistic deep learning settings.","PeriodicalId":48863,"journal":{"name":"Acta Numerica","volume":"30 1","pages":"87 - 201"},"PeriodicalIF":14.2,"publicationDate":"2021-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0962492921000027","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41948779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 177
Neural network approximation 神经网络近似
IF 14.2 1区 数学 Q1 MATHEMATICS Pub Date : 2020-12-28 DOI: 10.1017/S0962492921000052
R. DeVore, B. Hanin, G. Petrova
Neural networks (NNs) are the method of choice for building learning algorithms. They are now being investigated for other numerical tasks such as solving high-dimensional partial differential equations. Their popularity stems from their empirical success on several challenging learning problems (computer chess/Go, autonomous navigation, face recognition). However, most scholars agree that a convincing theoretical explanation for this success is still lacking. Since these applications revolve around approximating an unknown function from data observations, part of the answer must involve the ability of NNs to produce accurate approximations. This article surveys the known approximation properties of the outputs of NNs with the aim of uncovering the properties that are not present in the more traditional methods of approximation used in numerical analysis, such as approximations using polynomials, wavelets, rational functions and splines. Comparisons are made with traditional approximation methods from the viewpoint of rate distortion, i.e. error versus the number of parameters used to create the approximant. Another major component in the analysis of numerical approximation is the computational time needed to construct the approximation, and this in turn is intimately connected with the stability of the approximation algorithm. So the stability of numerical approximation using NNs is a large part of the analysis put forward. The survey, for the most part, is concerned with NNs using the popular ReLU activation function. In this case the outputs of the NNs are piecewise linear functions on rather complicated partitions of the domain of f into cells that are convex polytopes. When the architecture of the NN is fixed and the parameters are allowed to vary, the set of output functions of the NN is a parametrized nonlinear manifold. It is shown that this manifold has certain space-filling properties leading to an increased ability to approximate (better rate distortion) but at the expense of numerical stability. The space filling creates the challenge to the numerical method of finding best or good parameter choices when trying to approximate.
神经网络是构建学习算法的首选方法。它们现在正被研究用于其他数值任务,如求解高维偏微分方程。他们的受欢迎源于他们在几个具有挑战性的学习问题(计算机象棋/围棋、自主导航、人脸识别)上的经验成功。然而,大多数学者一致认为,对这一成功仍然缺乏令人信服的理论解释。由于这些应用程序围绕着从数据观测中近似未知函数,因此部分答案必须涉及神经网络产生准确近似的能力。本文调查了神经网络输出的已知近似性质,目的是揭示数值分析中使用的更传统的近似方法中不存在的性质,例如使用多项式、小波、有理函数和样条的近似。从速率失真的角度与传统近似方法进行了比较,即误差与用于创建近似的参数数量的关系。数值近似分析的另一个主要组成部分是构造近似所需的计算时间,而这反过来又与近似算法的稳定性密切相关。因此,使用神经网络进行数值逼近的稳定性是分析的重要组成部分。该调查在很大程度上涉及使用流行的ReLU激活功能的NN。在这种情况下,NN的输出是在f的域的相当复杂的划分上的分段线性函数,这些划分为凸多面体的单元。当神经网络的结构是固定的并且允许参数变化时,神经网络的输出函数集是一个参数化的非线性流形。结果表明,该流形具有一定的空间填充特性,从而提高了近似能力(更好的速率失真),但以牺牲数值稳定性为代价。空间填充对试图近似时寻找最佳或良好参数选择的数值方法提出了挑战。
{"title":"Neural network approximation","authors":"R. DeVore, B. Hanin, G. Petrova","doi":"10.1017/S0962492921000052","DOIUrl":"https://doi.org/10.1017/S0962492921000052","url":null,"abstract":"Neural networks (NNs) are the method of choice for building learning algorithms. They are now being investigated for other numerical tasks such as solving high-dimensional partial differential equations. Their popularity stems from their empirical success on several challenging learning problems (computer chess/Go, autonomous navigation, face recognition). However, most scholars agree that a convincing theoretical explanation for this success is still lacking. Since these applications revolve around approximating an unknown function from data observations, part of the answer must involve the ability of NNs to produce accurate approximations. This article surveys the known approximation properties of the outputs of NNs with the aim of uncovering the properties that are not present in the more traditional methods of approximation used in numerical analysis, such as approximations using polynomials, wavelets, rational functions and splines. Comparisons are made with traditional approximation methods from the viewpoint of rate distortion, i.e. error versus the number of parameters used to create the approximant. Another major component in the analysis of numerical approximation is the computational time needed to construct the approximation, and this in turn is intimately connected with the stability of the approximation algorithm. So the stability of numerical approximation using NNs is a large part of the analysis put forward. The survey, for the most part, is concerned with NNs using the popular ReLU activation function. In this case the outputs of the NNs are piecewise linear functions on rather complicated partitions of the domain of f into cells that are convex polytopes. When the architecture of the NN is fixed and the parameters are allowed to vary, the set of output functions of the NN is a parametrized nonlinear manifold. It is shown that this manifold has certain space-filling properties leading to an increased ability to approximate (better rate distortion) but at the expense of numerical stability. The space filling creates the challenge to the numerical method of finding best or good parameter choices when trying to approximate.","PeriodicalId":48863,"journal":{"name":"Acta Numerica","volume":"30 1","pages":"327 - 444"},"PeriodicalIF":14.2,"publicationDate":"2020-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47549585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 111
Numerical methods for nonlocal and fractional models 非局部和分数阶模型的数值方法
IF 14.2 1区 数学 Q1 MATHEMATICS Pub Date : 2020-11-30 DOI: 10.1017/s096249292000001x
Marta D’Elia, Qiang Du, Christian Glusa, Max Gunzburger, Xiaochuan Tian, Zhi Zhou
Partial differential equations (PDEs) are used with huge success to model phenomena across all scientific and engineering disciplines. However, across an equally wide swath, there exist situations in which PDEs fail to adequately model observed phenomena, or are not the best available model for that purpose. On the other hand, in many situations,nonlocal modelsthat account for interaction occurring at a distance have been shown to more faithfully and effectively model observed phenomena that involve possible singularities and other anomalies. In this article we consider a generic nonlocal model, beginning with a short review of its definition, the properties of its solution, its mathematical analysis and of specific concrete examples. We then provide extensive discussions about numerical methods, including finite element, finite difference and spectral methods, for determining approximate solutions of the nonlocal models considered. In that discussion, we pay particular attention to a special class of nonlocal models that are the most widely studied in the literature, namely those involving fractional derivatives. The article ends with brief considerations of several modelling and algorithmic extensions, which serve to show the wide applicability of nonlocal modelling.
偏微分方程(PDEs)在所有科学和工程学科中都被成功地用于建模现象。然而,在同样广泛的范围内,存在着一些情况,其中偏微分方程不能充分模拟观察到的现象,或者不是用于这一目的的最佳可用模型。另一方面,在许多情况下,考虑到发生在远处的相互作用的非局部模型已被证明更忠实和有效地模拟涉及可能的奇点和其他异常的观测现象。在本文中,我们考虑一个一般的非局部模型,从它的定义、解的性质、数学分析和具体例子的简短回顾开始。然后,我们提供了关于数值方法的广泛讨论,包括有限元,有限差分和谱方法,用于确定所考虑的非局部模型的近似解。在讨论中,我们特别关注文献中研究最广泛的一类特殊的非局部模型,即那些涉及分数阶导数的模型。文章最后简要考虑了几种建模和算法扩展,这表明了非局部建模的广泛适用性。
{"title":"Numerical methods for nonlocal and fractional models","authors":"Marta D’Elia, Qiang Du, Christian Glusa, Max Gunzburger, Xiaochuan Tian, Zhi Zhou","doi":"10.1017/s096249292000001x","DOIUrl":"https://doi.org/10.1017/s096249292000001x","url":null,"abstract":"Partial differential equations (PDEs) are used with huge success to model phenomena across all scientific and engineering disciplines. However, across an equally wide swath, there exist situations in which PDEs fail to adequately model observed phenomena, or are not the best available model for that purpose. On the other hand, in many situations,<jats:italic>nonlocal models</jats:italic>that account for interaction occurring at a distance have been shown to more faithfully and effectively model observed phenomena that involve possible singularities and other anomalies. In this article we consider a generic nonlocal model, beginning with a short review of its definition, the properties of its solution, its mathematical analysis and of specific concrete examples. We then provide extensive discussions about numerical methods, including finite element, finite difference and spectral methods, for determining approximate solutions of the nonlocal models considered. In that discussion, we pay particular attention to a special class of nonlocal models that are the most widely studied in the literature, namely those involving fractional derivatives. The article ends with brief considerations of several modelling and algorithmic extensions, which serve to show the wide applicability of nonlocal modelling.","PeriodicalId":48863,"journal":{"name":"Acta Numerica","volume":"26 1","pages":""},"PeriodicalIF":14.2,"publicationDate":"2020-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138530497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Fast algorithms using orthogonal polynomials 使用正交多项式的快速算法
IF 14.2 1区 数学 Q1 MATHEMATICS Pub Date : 2020-05-01 DOI: 10.1017/S0962492920000045
S. Olver, R. Slevinsky, Alex Townsend
We review recent advances in algorithms for quadrature, transforms, differential equations and singular integral equations using orthogonal polynomials. Quadrature based on asymptotics has facilitated optimal complexity quadrature rules, allowing for efficient computation of quadrature rules with millions of nodes. Transforms based on rank structures in change-of-basis operators allow for quasi-optimal complexity, including in multivariate settings such as on triangles and for spherical harmonics. Ordinary and partial differential equations can be solved via sparse linear algebra when set up using orthogonal polynomials as a basis, provided that care is taken with the weights of orthogonality. A similar idea, together with low-rank approximation, gives an efficient method for solving singular integral equations. These techniques can be combined to produce high-performance codes for a wide range of problems that appear in applications.
我们回顾了正交多项式在求积、变换、微分方程和奇异积分方程算法方面的最新进展。基于渐近线的求积促进了最优复杂度求积规则,允许使用数百万节点高效计算求积规则。基于变基算子中的秩结构的变换允许准最优复杂度,包括在多变量设置中,如三角形和球面谐波。当使用正交多项式作为基础建立常微分方程和偏微分方程时,只要注意正交性的权重,就可以通过稀疏线性代数来求解。类似的思想,结合低阶近似,给出了一种求解奇异积分方程的有效方法。这些技术可以结合起来,为应用程序中出现的各种问题生成高性能代码。
{"title":"Fast algorithms using orthogonal polynomials","authors":"S. Olver, R. Slevinsky, Alex Townsend","doi":"10.1017/S0962492920000045","DOIUrl":"https://doi.org/10.1017/S0962492920000045","url":null,"abstract":"We review recent advances in algorithms for quadrature, transforms, differential equations and singular integral equations using orthogonal polynomials. Quadrature based on asymptotics has facilitated optimal complexity quadrature rules, allowing for efficient computation of quadrature rules with millions of nodes. Transforms based on rank structures in change-of-basis operators allow for quasi-optimal complexity, including in multivariate settings such as on triangles and for spherical harmonics. Ordinary and partial differential equations can be solved via sparse linear algebra when set up using orthogonal polynomials as a basis, provided that care is taken with the weights of orthogonality. A similar idea, together with low-rank approximation, gives an efficient method for solving singular integral equations. These techniques can be combined to produce high-performance codes for a wide range of problems that appear in applications.","PeriodicalId":48863,"journal":{"name":"Acta Numerica","volume":"29 1","pages":"573 - 699"},"PeriodicalIF":14.2,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0962492920000045","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49221314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 29
ANU volume 29 Cover and Back matter 澳大利亚国立大学第29卷封面和封底
IF 14.2 1区 数学 Q1 MATHEMATICS Pub Date : 2020-05-01 DOI: 10.1017/s0962492920000082
M. D'Elia, Q. Du, Christian A. Glusa, M. Gunzburger, X. Tian
{"title":"ANU volume 29 Cover and Back matter","authors":"M. D'Elia, Q. Du, Christian A. Glusa, M. Gunzburger, X. Tian","doi":"10.1017/s0962492920000082","DOIUrl":"https://doi.org/10.1017/s0962492920000082","url":null,"abstract":"","PeriodicalId":48863,"journal":{"name":"Acta Numerica","volume":"29 1","pages":"b1 - b2"},"PeriodicalIF":14.2,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/s0962492920000082","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42777579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Essentially non-oscillatory and weighted essentially non-oscillatory schemes 本质无振荡和加权本质无振荡格式
IF 14.2 1区 数学 Q1 MATHEMATICS Pub Date : 2020-05-01 DOI: 10.1017/S0962492920000057
Chi-Wang Shu
Essentially non-oscillatory (ENO) and weighted ENO (WENO) schemes were designed for solving hyperbolic and convection–diffusion equations with possibly discontinuous solutions or solutions with sharp gradient regions. The main idea of ENO and WENO schemes is actually an approximation procedure, aimed at achieving arbitrarily high-order accuracy in smooth regions and resolving shocks or other discontinuities sharply and in an essentially non-oscillatory fashion. Both finite volume and finite difference schemes have been designed using the ENO or WENO procedure, and these schemes are very popular in applications, most noticeably in computational fluid dynamics but also in other areas of computational physics and engineering. Since the main idea of the ENO and WENO schemes is an approximation procedure not directly related to partial differential equations (PDEs), ENO and WENO schemes also have non-PDE applications. In this paper we will survey the basic ideas behind ENO and WENO schemes, discuss their properties, and present examples of their applications to different types of PDEs as well as to non-PDE problems.
设计了本质无振荡(ENO)和加权ENO(WENO)格式,用于求解具有可能不连续解或具有尖锐梯度区域的解的双曲型和对流-扩散方程。ENO和WENO格式的主要思想实际上是一种近似过程,旨在在光滑区域实现任意高阶精度,并以基本上无振荡的方式快速解决冲击或其他不连续性。有限体积和有限差分格式都是使用ENO或WENO程序设计的,这些格式在应用中非常受欢迎,最引人注目的是在计算流体动力学中,也在计算物理和工程的其他领域。由于ENO和WENO格式的主要思想是与偏微分方程(PDE)没有直接关系的近似过程,因此ENO和WENO格式也具有非PDE应用。在本文中,我们将调查ENO和WENO方案背后的基本思想,讨论它们的性质,并举例说明它们在不同类型的偏微分方程和非偏微分方程问题中的应用。
{"title":"Essentially non-oscillatory and weighted essentially non-oscillatory schemes","authors":"Chi-Wang Shu","doi":"10.1017/S0962492920000057","DOIUrl":"https://doi.org/10.1017/S0962492920000057","url":null,"abstract":"Essentially non-oscillatory (ENO) and weighted ENO (WENO) schemes were designed for solving hyperbolic and convection–diffusion equations with possibly discontinuous solutions or solutions with sharp gradient regions. The main idea of ENO and WENO schemes is actually an approximation procedure, aimed at achieving arbitrarily high-order accuracy in smooth regions and resolving shocks or other discontinuities sharply and in an essentially non-oscillatory fashion. Both finite volume and finite difference schemes have been designed using the ENO or WENO procedure, and these schemes are very popular in applications, most noticeably in computational fluid dynamics but also in other areas of computational physics and engineering. Since the main idea of the ENO and WENO schemes is an approximation procedure not directly related to partial differential equations (PDEs), ENO and WENO schemes also have non-PDE applications. In this paper we will survey the basic ideas behind ENO and WENO schemes, discuss their properties, and present examples of their applications to different types of PDEs as well as to non-PDE problems.","PeriodicalId":48863,"journal":{"name":"Acta Numerica","volume":"29 1","pages":"701 - 762"},"PeriodicalIF":14.2,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0962492920000057","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43164320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 74
ANU volume 29 Cover and Front matter 澳大利亚国立大学第29卷封面和封面
IF 14.2 1区 数学 Q1 MATHEMATICS Pub Date : 2020-05-01 DOI: 10.1017/s0962492920000070
M. D'Elia, Q. Du, Christian A. Glusa, M. Gunzburger, X. Tian, T. Strohmer, C. Lubich, Chi-Wang Shu
{"title":"ANU volume 29 Cover and Front matter","authors":"M. D'Elia, Q. Du, Christian A. Glusa, M. Gunzburger, X. Tian, T. Strohmer, C. Lubich, Chi-Wang Shu","doi":"10.1017/s0962492920000070","DOIUrl":"https://doi.org/10.1017/s0962492920000070","url":null,"abstract":"","PeriodicalId":48863,"journal":{"name":"Acta Numerica","volume":"29 1","pages":"f1 - f6"},"PeriodicalIF":14.2,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/s0962492920000070","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43236134","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Randomized numerical linear algebra: Foundations and algorithms 随机数值线性代数:基础和算法
IF 14.2 1区 数学 Q1 MATHEMATICS Pub Date : 2020-05-01 DOI: 10.1017/S0962492920000021
P. Martinsson, J. Tropp
This survey describes probabilistic algorithms for linear algebraic computations, such as factorizing matrices and solving linear systems. It focuses on techniques that have a proven track record for real-world problems. The paper treats both the theoretical foundations of the subject and practical computational issues. Topics include norm estimation, matrix approximation by sampling, structured and unstructured random embeddings, linear regression problems, low-rank approximation, subspace iteration and Krylov methods, error estimation and adaptivity, interpolatory and CUR factorizations, Nyström approximation of positive semidefinite matrices, single-view (‘streaming’) algorithms, full rank-revealing factorizations, solvers for linear systems, and approximation of kernel matrices that arise in machine learning and in scientific computing.
本文描述线性代数计算的概率算法,如分解矩阵和求解线性系统。它关注的是那些在解决实际问题方面有良好记录的技术。本文讨论了这门学科的理论基础和实际计算问题。主题包括范数估计,抽样矩阵近似,结构化和非结构化随机嵌入,线性回归问题,低秩近似,子空间迭代和Krylov方法,误差估计和自适应,插值和CUR分解,Nyström正半定矩阵的近似,单视图(“流”)算法,全秩揭示分解,线性系统的求解器,以及在机器学习和科学计算中出现的核矩阵的近似。
{"title":"Randomized numerical linear algebra: Foundations and algorithms","authors":"P. Martinsson, J. Tropp","doi":"10.1017/S0962492920000021","DOIUrl":"https://doi.org/10.1017/S0962492920000021","url":null,"abstract":"This survey describes probabilistic algorithms for linear algebraic computations, such as factorizing matrices and solving linear systems. It focuses on techniques that have a proven track record for real-world problems. The paper treats both the theoretical foundations of the subject and practical computational issues. Topics include norm estimation, matrix approximation by sampling, structured and unstructured random embeddings, linear regression problems, low-rank approximation, subspace iteration and Krylov methods, error estimation and adaptivity, interpolatory and CUR factorizations, Nyström approximation of positive semidefinite matrices, single-view (‘streaming’) algorithms, full rank-revealing factorizations, solvers for linear systems, and approximation of kernel matrices that arise in machine learning and in scientific computing.","PeriodicalId":48863,"journal":{"name":"Acta Numerica","volume":"29 1","pages":"403 - 572"},"PeriodicalIF":14.2,"publicationDate":"2020-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0962492920000021","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"57446663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 208
The numerics of phase retrieval 相位恢复的数值
IF 14.2 1区 数学 Q1 MATHEMATICS Pub Date : 2020-04-13 DOI: 10.1017/S0962492920000069
A. Fannjiang, T. Strohmer
Phase retrieval, i.e. the problem of recovering a function from the squared magnitude of its Fourier transform, arises in many applications, such as X-ray crystallography, diffraction imaging, optics, quantum mechanics and astronomy. This problem has confounded engineers, physicists, and mathematicians for many decades. Recently, phase retrieval has seen a resurgence in research activity, ignited by new imaging modalities and novel mathematical concepts. As our scientific experiments produce larger and larger datasets and we aim for faster and faster throughput, it is becoming increasingly important to study the involved numerical algorithms in a systematic and principled manner. Indeed, the past decade has witnessed a surge in the systematic study of computational algorithms for phase retrieval. In this paper we will review these recent advances from a numerical viewpoint.
相位恢复,即从其傅里叶变换的平方幅度中恢复函数的问题,在许多应用中出现,如x射线晶体学,衍射成像,光学,量子力学和天文学。这个问题困扰了工程师、物理学家和数学家几十年。最近,在新的成像模式和新的数学概念的推动下,相位检索在研究活动中重新兴起。随着我们的科学实验产生越来越大的数据集,我们的目标是越来越快的吞吐量,以系统和原则性的方式研究所涉及的数值算法变得越来越重要。事实上,在过去的十年中,相位检索的计算算法的系统研究激增。在本文中,我们将从数值角度回顾这些最新进展。
{"title":"The numerics of phase retrieval","authors":"A. Fannjiang, T. Strohmer","doi":"10.1017/S0962492920000069","DOIUrl":"https://doi.org/10.1017/S0962492920000069","url":null,"abstract":"Phase retrieval, i.e. the problem of recovering a function from the squared magnitude of its Fourier transform, arises in many applications, such as X-ray crystallography, diffraction imaging, optics, quantum mechanics and astronomy. This problem has confounded engineers, physicists, and mathematicians for many decades. Recently, phase retrieval has seen a resurgence in research activity, ignited by new imaging modalities and novel mathematical concepts. As our scientific experiments produce larger and larger datasets and we aim for faster and faster throughput, it is becoming increasingly important to study the involved numerical algorithms in a systematic and principled manner. Indeed, the past decade has witnessed a surge in the systematic study of computational algorithms for phase retrieval. In this paper we will review these recent advances from a numerical viewpoint.","PeriodicalId":48863,"journal":{"name":"Acta Numerica","volume":"29 1","pages":"125 - 228"},"PeriodicalIF":14.2,"publicationDate":"2020-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1017/S0962492920000069","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41678878","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 66
期刊
Acta Numerica
全部 Acc. Chem. Res. ACS Applied Bio Materials ACS Appl. Electron. Mater. ACS Appl. Energy Mater. ACS Appl. Mater. Interfaces ACS Appl. Nano Mater. ACS Appl. Polym. Mater. ACS BIOMATER-SCI ENG ACS Catal. ACS Cent. Sci. ACS Chem. Biol. ACS Chemical Health & Safety ACS Chem. Neurosci. ACS Comb. Sci. ACS Earth Space Chem. ACS Energy Lett. ACS Infect. Dis. ACS Macro Lett. ACS Mater. Lett. ACS Med. Chem. Lett. ACS Nano ACS Omega ACS Photonics ACS Sens. ACS Sustainable Chem. Eng. ACS Synth. Biol. Anal. Chem. BIOCHEMISTRY-US Bioconjugate Chem. BIOMACROMOLECULES Chem. Res. Toxicol. Chem. Rev. Chem. Mater. CRYST GROWTH DES ENERG FUEL Environ. Sci. Technol. Environ. Sci. Technol. Lett. Eur. J. Inorg. Chem. IND ENG CHEM RES Inorg. Chem. J. Agric. Food. Chem. J. Chem. Eng. Data J. Chem. Educ. J. Chem. Inf. Model. J. Chem. Theory Comput. J. Med. Chem. J. Nat. Prod. J PROTEOME RES J. Am. Chem. Soc. LANGMUIR MACROMOLECULES Mol. Pharmaceutics Nano Lett. Org. Lett. ORG PROCESS RES DEV ORGANOMETALLICS J. Org. Chem. J. Phys. Chem. J. Phys. Chem. A J. Phys. Chem. B J. Phys. Chem. C J. Phys. Chem. Lett. Analyst Anal. Methods Biomater. Sci. Catal. Sci. Technol. Chem. Commun. Chem. Soc. Rev. CHEM EDUC RES PRACT CRYSTENGCOMM Dalton Trans. Energy Environ. Sci. ENVIRON SCI-NANO ENVIRON SCI-PROC IMP ENVIRON SCI-WAT RES Faraday Discuss. Food Funct. Green Chem. Inorg. Chem. Front. Integr. Biol. J. Anal. At. Spectrom. J. Mater. Chem. A J. Mater. Chem. B J. Mater. Chem. C Lab Chip Mater. Chem. Front. Mater. Horiz. MEDCHEMCOMM Metallomics Mol. Biosyst. Mol. Syst. Des. Eng. Nanoscale Nanoscale Horiz. Nat. Prod. Rep. New J. Chem. Org. Biomol. Chem. Org. Chem. Front. PHOTOCH PHOTOBIO SCI PCCP Polym. Chem.
×
引用
GB/T 7714-2015
复制
MLA
复制
APA
复制
导出至
BibTeX EndNote RefMan NoteFirst NoteExpress
×
0
微信
客服QQ
Book学术公众号 扫码关注我们
反馈
×
意见反馈
请填写您的意见或建议
请填写您的手机或邮箱
×
提示
您的信息不完整,为了账户安全,请先补充。
现在去补充
×
提示
您因"违规操作"
具体请查看互助需知
我知道了
×
提示
现在去查看 取消
×
提示
确定
Book学术官方微信
Book学术文献互助
Book学术文献互助群
群 号:481959085
Book学术
文献互助 智能选刊 最新文献 互助须知 联系我们:info@booksci.cn
Book学术提供免费学术资源搜索服务,方便国内外学者检索中英文文献。致力于提供最便捷和优质的服务体验。
Copyright © 2023 Book学术 All rights reserved.
ghs 京公网安备 11010802042870号 京ICP备2023020795号-1