Matrices and Linear Algebra
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
New Algorithms in the Frobenius Matrix Algebra for Polynomial Root-Finding
City University of New York (CUNY) CUNY Academic Works Computer Science Technical Reports CUNY Academic Works 2014 TR-2014006: New Algorithms in the Frobenius Matrix Algebra for Polynomial Root-Finding Victor Y. Pan Ai-Long Zheng How does access to this work benefit ou?y Let us know! More information about this work at: https://academicworks.cuny.edu/gc_cs_tr/397 Discover additional works at: https://academicworks.cuny.edu This work is made publicly available by the City University of New York (CUNY). Contact: [email protected] New Algoirthms in the Frobenius Matrix Algebra for Polynomial Root-finding ∗ Victor Y. Pan[1,2],[a] and Ai-Long Zheng[2],[b] Supported by NSF Grant CCF-1116736 and PSC CUNY Award 64512–0042 [1] Department of Mathematics and Computer Science Lehman College of the City University of New York Bronx, NY 10468 USA [2] Ph.D. Programs in Mathematics and Computer Science The Graduate Center of the City University of New York New York, NY 10036 USA [a] [email protected] http://comet.lehman.cuny.edu/vpan/ [b] [email protected] Abstract In 1996 Cardinal applied fast algorithms in Frobenius matrix algebra to complex root-finding for univariate polynomials, but he resorted to some numerically unsafe techniques of symbolic manipulation with polynomials at the final stages of his algorithms. We extend his work to complete the computations by operating with matrices at the final stage as well and also to adjust them to real polynomial root-finding. Our analysis and experiments show efficiency of the resulting algorithms. 2000 Math. -
C H a P T E R § Methods Related to the Norm Al Equations
¡ ¢ £ ¤ ¥ ¦ § ¨ © © © © ¨ ©! "# $% &('*),+-)(./+-)0.21434576/),+98,:%;<)>=,'41/? @%3*)BAC:D8E+%=B891GF*),+H;I?H1KJ2.21K8L1GMNAPO45Q5R)S;S+T? =RU ?H1*)>./+EAVOKAPM ;<),5 ?H1G;P8W.XAVO4575R)S;S+Y? =Z8L1*)/[%\Z1*)]AB3*=,'Q;<)B=,'41/? @%3*)RAP8LU F*)BA(;S'*)Z)>@%3/? F*.4U ),1G;^U ?H1*)>./+ APOKAP;_),5a`Rbc`^dfeg`Rbih,jk=>.4U U )Blm;B'*)n1K84+o5R.EUp)B@%3*.K;q? 8L1KA>[r\0:D;_),1Ejp;B'/? A2.4s4s/+t8/.,=,' b ? A7.KFK84? l4)>lu?H1vs,+D.*=S;q? =>)m6/)>=>.43KA<)W;B'*)w=B8E)IxW=K? ),1G;W5R.K;S+Y? yn` `z? AW5Q3*=,'|{}84+-A_) =B8L1*l9? ;I? 891*)>lX;B'*.41Q`7[r~k8K{i)IF*),+NjL;B'*)71K8E+o5R.4U4)>@%3*.G;I? 891KA0.4s4s/+t8.*=,'w5R.BOw6/)Z.,l4)IM @%3*.K;_)7?H17A_8L5R)QAI? ;S3*.K;q? 8L1KA>[p1*l4)>)>lj9;B'*),+-)Q./+-)Q)SF*),1.Es4s4U ? =>.K;q? 8L1KA(?H1Q{R'/? =,'W? ;R? A s/+-)S:Y),+o+D)Blm;_8|;B'*)W3KAB3*.4Urc+HO4U 8,F|AS346KABs*.,=B)Q;_)>=,'41/? @%3*)BAB[&('/? A]=*'*.EsG;_),+}=B8*F*),+tA7? ;PM ),+-.K;q? F*)75R)S;S'K8ElAi{^'/? =,'Z./+-)R)K? ;B'*),+pl9?+D)B=S;BU OR84+k?H5Qs4U ? =K? ;BU O2+-),U .G;<)Bl7;_82;S'*)Q1K84+o5R.EU )>@%3*.G;I? 891KA>[ mWX(fQ - uK In order to solve the linear system 7 when is nonsymmetric, we can solve the equivalent system b b [¥K¦ ¡¢ £N¤ which is Symmetric Positive Definite. This system is known as the system of the normal equations associated with the least-squares problem, [ ¦ £N¤ minimize §* R¨©7ª§*«9¬ Note that (8.1) is typically used to solve the least-squares problem (8.2) for over- ®°¯± ±²³® determined systems, i.e., when is a rectangular matrix of size , . -
The Column and Row Hilbert Operator Spaces
The Column and Row Hilbert Operator Spaces Roy M. Araiza Department of Mathematics Purdue University Abstract Given a Hilbert space H we present the construction and some properties of the column and row Hilbert operator spaces Hc and Hr, respectively. The main proof of the survey is showing that CB(Hc; Kc) is completely isometric to B(H ; K ); in other words, the completely bounded maps be- tween the corresponding column Hilbert operator spaces is completely isometric to the bounded operators between the Hilbert spaces. A similar theorem for the row Hilbert operator spaces follows via duality of the operator spaces. In particular there exists a natural duality between the column and row Hilbert operator spaces which we also show. The presentation and proofs are due to Effros and Ruan [1]. 1 The Column Hilbert Operator Space Given a Hilbert space H , we define the column isometry C : H −! B(C; H ) given by ξ 7! C(ξ)α := αξ; α 2 C: Then given any n 2 N; we define the nth-matrix norm on Mn(H ); by (n) kξkc;n = C (ξ) ; ξ 2 Mn(H ): These are indeed operator space matrix norms by Ruan's Representation theorem and thus we define the column Hilbert operator space as n o Hc = H ; k·kc;n : n2N It follows that given ξ 2 Mn(H ) we have that the adjoint operator of C(ξ) is given by ∗ C(ξ) : H −! C; ζ 7! (ζj ξ) : Suppose C(ξ)∗(ζ) = d; c 2 C: Then we see that cd = (cj C(ξ)∗(ζ)) = (cξj ζ) = c(ζj ξ) = (cj (ζj ξ)) : We are also able to compute the matrix norms on rectangular matrices. -
Subspace-Preserving Sparsification of Matrices with Minimal Perturbation
Subspace-preserving sparsification of matrices with minimal perturbation to the near null-space. Part I: Basics Chetan Jhurani Tech-X Corporation 5621 Arapahoe Ave Boulder, Colorado 80303, U.S.A. Abstract This is the first of two papers to describe a matrix sparsification algorithm that takes a general real or complex matrix as input and produces a sparse output matrix of the same size. The non-zero entries in the output are chosen to minimize changes to the singular values and singular vectors corresponding to the near null-space of the input. The output matrix is constrained to preserve left and right null-spaces exactly. The sparsity pattern of the output matrix is automatically determined or can be given as input. If the input matrix belongs to a common matrix subspace, we prove that the computed sparse matrix belongs to the same subspace. This works with- out imposing explicit constraints pertaining to the subspace. This property holds for the subspaces of Hermitian, complex-symmetric, Hamiltonian, cir- culant, centrosymmetric, and persymmetric matrices, and for each of the skew counterparts. Applications of our method include computation of reusable sparse pre- conditioning matrices for reliable and efficient solution of high-order finite element systems. The second paper in this series [1] describes our open- arXiv:1304.7049v1 [math.NA] 26 Apr 2013 source implementation, and presents further technical details. Keywords: Sparsification, Spectral equivalence, Matrix structure, Convex optimization, Moore-Penrose pseudoinverse Email address: [email protected] (Chetan Jhurani) Preprint submitted to Computers and Mathematics with Applications October 10, 2018 1. Introduction We present and analyze a matrix-valued optimization problem formulated to sparsify matrices while preserving the matrix null-spaces and certain spe- cial structural properties. -
A Logarithmic Minimization Property of the Unitary Polar Factor in The
A logarithmic minimization property of the unitary polar factor in the spectral norm and the Frobenius matrix norm Patrizio Neff∗ Yuji Nakatsukasa† Andreas Fischle‡ October 30, 2018 Abstract The unitary polar factor Q = Up in the polar decomposition of Z = Up H is the minimizer over unitary matrices Q for both Log(Q∗Z) 2 and its Hermitian part k k sym (Log(Q∗Z)) 2 over both R and C for any given invertible matrix Z Cn×n and k * k ∈ any matrix logarithm Log, not necessarily the principal logarithm log. We prove this for the spectral matrix norm for any n and for the Frobenius matrix norm in two and three dimensions. The result shows that the unitary polar factor is the nearest orthogonal matrix to Z not only in the normwise sense, but also in a geodesic distance. The derivation is based on Bhatia’s generalization of Bernstein’s trace inequality for the matrix exponential and a new sum of squared logarithms inequality. Our result generalizes the fact for scalars that for any complex logarithm and for all z C 0 ∈ \ { } −iϑ 2 2 −iϑ 2 2 min LogC(e z) = log z , min Re LogC(e z) = log z . ϑ∈(−π,π] | | | | || ϑ∈(−π,π] | | | | || Keywords: unitary polar factor, matrix logarithm, matrix exponential, Hermitian part, minimization, unitarily invariant norm, polar decomposition, sum of squared logarithms in- equality, optimality, matrix Lie-group, geodesic distance arXiv:1302.3235v4 [math.CA] 2 Jan 2014 AMS 2010 subject classification: 15A16, 15A18, 15A24, 15A44, 15A45, 26Dxx ∗Corresponding author, Head of Lehrstuhl f¨ur Nichtlineare Analysis und Modellierung, Fakult¨at f¨ur Mathematik, Universit¨at Duisburg-Essen, Campus Essen, Thea-Leymann Str. -
Lecture 5 Ch. 5, Norms for Vectors and Matrices
KTH ROYAL INSTITUTE OF TECHNOLOGY Norms for vectors and matrices — Why? Lecture 5 Problem: Measure size of vector or matrix. What is “small” and what is “large”? Ch. 5, Norms for vectors and matrices Problem: Measure distance between vectors or matrices. When are they “close together” or “far apart”? Emil Björnson/Magnus Jansson/Mats Bengtsson April 27, 2016 Answers are given by norms. Also: Tool to analyze convergence and stability of algorithms. 2 / 21 Vector norm — axiomatic definition Inner product — axiomatic definition Definition: LetV be a vector space over afieldF(R orC). Definition: LetV be a vector space over afieldF(R orC). A function :V R is a vector norm if for all A function , :V V F is an inner product if for all || · || → �· ·� × → x,y V x,y,z V, ∈ ∈ (1) x 0 nonnegative (1) x,x 0 nonnegative || ||≥ � �≥ (1a) x =0iffx= 0 positive (1a) x,x =0iffx=0 positive || || � � (2) cx = c x for allc F homogeneous (2) x+y,z = x,z + y,z additive || || | | || || ∈ � � � � � � (3) x+y x + y triangle inequality (3) cx,y =c x,y for allc F homogeneous || ||≤ || || || || � � � � ∈ (4) x,y = y,x Hermitian property A function not satisfying (1a) is called a vector � � � � seminorm. Interpretation: “Angle” (distance) between vectors. Interpretation: Size/length of vector. 3 / 21 4 / 21 Connections between norm and inner products Examples / Corollary: If , is an inner product, then x =( x,x ) 1 2 � The Euclidean norm (l ) onC n: �· ·� || || � � 2 is a vector norm. 2 2 2 1/2 x 2 = ( x1 + x 2 + + x n ) . Called: Vector norm derived from an inner product. -
Matrix Norms 30.4
Matrix Norms 30.4 Introduction A matrix norm is a number defined in terms of the entries of the matrix. The norm is a useful quantity which can give important information about a matrix. ' • be familiar with matrices and their use in $ writing systems of equations • revise material on matrix inverses, be able to find the inverse of a 2 × 2 matrix, and know Prerequisites when no inverse exists Before starting this Section you should ... • revise Gaussian elimination and partial pivoting • be aware of the discussion of ill-conditioned and well-conditioned problems earlier in Section 30.1 #& • calculate norms and condition numbers of % Learning Outcomes small matrices • adjust certain systems of equations with a On completion you should be able to ... view to better conditioning " ! 34 HELM (2008): Workbook 30: Introduction to Numerical Methods ® 1. Matrix norms The norm of a square matrix A is a non-negative real number denoted kAk. There are several different ways of defining a matrix norm, but they all share the following properties: 1. kAk ≥ 0 for any square matrix A. 2. kAk = 0 if and only if the matrix A = 0. 3. kkAk = |k| kAk, for any scalar k. 4. kA + Bk ≤ kAk + kBk. 5. kABk ≤ kAk kBk. The norm of a matrix is a measure of how large its elements are. It is a way of determining the “size” of a matrix that is not necessarily related to how many rows or columns the matrix has. Key Point 6 Matrix Norm The norm of a matrix is a real number which is a measure of the magnitude of the matrix. -
5 Norms on Linear Spaces
5 Norms on Linear Spaces 5.1 Introduction In this chapter we study norms on real or complex linear linear spaces. Definition 5.1. Let F = (F, {0, 1, +, −, ·}) be the real or the complex field. A semi-norm on an F -linear space V is a mapping ν : V −→ R that satisfies the following conditions: (i) ν(x + y) ≤ ν(x)+ ν(y) (the subadditivity property of semi-norms), and (ii) ν(ax)= |a|ν(x), for x, y ∈ V and a ∈ F . By taking a = 0 in the second condition of the definition we have ν(0)=0 for every semi-norm on a real or complex space. A semi-norm can be defined on every linear space. Indeed, if B is a basis of V , B = {vi | i ∈ I}, J is a finite subset of I, and x = i∈I xivi, define νJ (x) as P 0 if x = 0, νJ (x)= ( j∈J |aj | for x ∈ V . We leave to the readerP the verification of the fact that νJ is indeed a seminorm. Theorem 5.2. If V is a real or complex linear space and ν : V −→ R is a semi-norm on V , then ν(x − y) ≥ |ν(x) − ν(y)|, for x, y ∈ V . Proof. We have ν(x) ≤ ν(x − y)+ ν(y), so ν(x) − ν(y) ≤ ν(x − y). (5.1) 160 5 Norms on Linear Spaces Since ν(x − y)= |− 1|ν(y − x) ≥ ν(y) − ν(x) we have −(ν(x) − ν(y)) ≤ ν(x) − ν(y). (5.2) The Inequalities 5.1 and 5.2 give the desired inequality. -
A Degeneracy Framework for Scalable Graph Autoencoders
Proceedings of the Twenty-Eighth International Joint Conference on Artificial Intelligence (IJCAI-19) A Degeneracy Framework for Scalable Graph Autoencoders Guillaume Salha1;2 , Romain Hennequin1 , Viet Anh Tran1 and Michalis Vazirgiannis2 1Deezer Research & Development, Paris, France 2Ecole´ Polytechnique, Palaiseau, France [email protected] Abstract In this paper, we focus on the graph extensions of autoen- coders and variational autoencoders. Introduced in the 1980’s In this paper, we present a general framework to [Rumelhart et al., 1986], autoencoders (AE) regained a sig- scale graph autoencoders (AE) and graph varia- nificant popularity in the last decade through neural network tional autoencoders (VAE). This framework lever- frameworks [Baldi, 2012] as efficient tools to learn reduced ages graph degeneracy concepts to train models encoding representations of input data in an unsupervised only from a dense subset of nodes instead of us- way. Furthermore, variational autoencoders (VAE) [Kingma ing the entire graph. Together with a simple yet ef- and Welling, 2013], described as extensions of AE but actu- fective propagation mechanism, our approach sig- ally based on quite different mathematical foundations, also nificantly improves scalability and training speed recently emerged as a successful approach for unsupervised while preserving performance. We evaluate and learning from complex distributions, assuming the input data discuss our method on several variants of existing is the observed part of a larger joint model involving low- graph AE and VAE, providing the first application dimensional latent variables, optimized via variational infer- of these models to large graphs with up to millions ence approximations. [Tschannen et al., 2018] review the of nodes and edges. -
Perron–Frobenius Theorem for Matrices with Some Negative Entries
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Linear Algebra and its Applications 328 (2001) 57–68 www.elsevier.com/locate/laa Perron–Frobenius theorem for matrices with some negative entries Pablo Tarazaga a,∗,1, Marcos Raydan b,2, Ana Hurman c aDepartment of Mathematics, University of Puerto Rico, P.O. Box 5000, Mayaguez Campus, Mayaguez, PR 00681-5000, USA bDpto. de Computación, Facultad de Ciencias, Universidad Central de Venezuela, Ap. 47002, Caracas 1041-A, Venezuela cFacultad de Ingeniería y Facultad de Ciencias Económicas, Universidad Nacional del Cuyo, Mendoza, Argentina Received 17 December 1998; accepted 24 August 2000 Submitted by R.A. Brualdi Abstract We extend the classical Perron–Frobenius theorem to matrices with some negative entries. We study the cone of matrices that has the matrix of 1’s (eet) as the central ray, and such that any matrix inside the cone possesses a Perron–Frobenius eigenpair. We also find the maximum angle of any matrix with eet that guarantees this property. © 2001 Elsevier Science Inc. All rights reserved. Keywords: Perron–Frobenius theorem; Cones of matrices; Optimality conditions 1. Introduction In 1907, Perron [4] made the fundamental discovery that the dominant eigenvalue of a matrix with all positive entries is positive and also that there exists a correspond- ing eigenvector with all positive entries. This result was later extended to nonnegative matrices by Frobenius [2] in 1912. In that case, there exists a nonnegative dominant ∗ Corresponding author. E-mail addresses: [email protected] (P. Tarazaga), [email protected] (M. -
Chapter 6 the Singular Value Decomposition Ax=B Version of 11 April 2019
Matrix Methods for Computational Modeling and Data Analytics Virginia Tech Spring 2019 · Mark Embree [email protected] Chapter 6 The Singular Value Decomposition Ax=b version of 11 April 2019 The singular value decomposition (SVD) is among the most important and widely applicable matrix factorizations. It provides a natural way to untangle a matrix into its four fundamental subspaces, and reveals the relative importance of each direction within those subspaces. Thus the singular value decomposition is a vital tool for analyzing data, and it provides a slick way to understand (and prove) many fundamental results in matrix theory. It is the perfect tool for solving least squares problems, and provides the best way to approximate a matrix with one of lower rank. These notes construct the SVD in various forms, then describe a few of its most compelling applications. 6.1 Eigenvalues and eigenvectors of symmetric matrices To derive the singular value decomposition of a general (rectangu- lar) matrix A IR m n, we shall rely on several special properties of 2 ⇥ the square, symmetric matrix ATA. While this course assumes you are well acquainted with eigenvalues and eigenvectors, we will re- call some fundamental concepts, especially pertaining to symmetric matrices. 6.1.1 A passing nod to complex numbers Recall that even if a matrix has real number entries, it could have eigenvalues that are complex numbers; the corresponding eigenvec- tors will also have complex entries. Consider, for example, the matrix 0 1 S = − . " 10# 73 To find the eigenvalues of S, form the characteristic polynomial l 1 det(lI S)=det = l2 + 1. -
Domain Generalization for Object Recognition with Multi-Task Autoencoders
Domain Generalization for Object Recognition with Multi-task Autoencoders Muhammad Ghifary W. Bastiaan Kleijn Mengjie Zhang David Balduzzi Victoria University of Wellington {muhammad.ghifary,bastiaan.kleijn,mengjie.zhang}@ecs.vuw.ac.nz, [email protected] Abstract mains. For example, frontal-views and 45◦ rotated-views correspond to two different domains. Alternatively, we can The problem of domain generalization is to take knowl- associate views or domains with standard image datasets edge acquired from a number of related domains where such as PASCAL VOC2007 [14], and Office [31]. training data is available, and to then successfully apply The problem of learning from multiple source domains it to previously unseen domains. We propose a new fea- and testing on unseen target domains is referred to as do- ture learning algorithm, Multi-Task Autoencoder (MTAE), main generalization [6, 26]. A domain is a probability P Nk that provides good generalization performance for cross- distribution k from which samples {xi,yi}i=1 are drawn. domain object recognition. Source domains provide training samples, whereas distinct Our algorithm extends the standard denoising autoen- target domains are used for testing. In the standard super- coder framework by substituting artificially induced cor- vised learning framework, it is assumed that the source and ruption with naturally occurring inter-domain variability in target domains coincide. Dataset bias becomes a significant the appearance of objects. Instead of reconstructing images problem when training and test domains differ: applying a from noisy versions, MTAE learns to transform the original classifier trained on one dataset to images sampled from an- image into analogs in multiple related domains.