The SVD-Fundamental Theorem of Linear Algebra

Given an m×n matrix A, with m ≥ n, the four subspaces associated with it are shown in Fig. 1 (see [1]). Fig. 1. The row spaces and the nullspaces of A and AT ; a1 through an and h1 through hm are abbreviations of the alignerframe and hangerframe vectors respectively (see [2]). The Fundamental Theore...

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Main Authors: A. G. Akritas, G. I. Malaschonok, P. S. Vigklas
Format: Article
Language:English
Published: Vilnius University Press 2006-05-01
Series:Nonlinear Analysis
Subjects:
Online Access:http://www.zurnalai.vu.lt/nonlinear-analysis/article/view/14753
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author A. G. Akritas
G. I. Malaschonok
P. S. Vigklas
author_facet A. G. Akritas
G. I. Malaschonok
P. S. Vigklas
author_sort A. G. Akritas
collection DOAJ
description Given an m×n matrix A, with m ≥ n, the four subspaces associated with it are shown in Fig. 1 (see [1]). Fig. 1. The row spaces and the nullspaces of A and AT ; a1 through an and h1 through hm are abbreviations of the alignerframe and hangerframe vectors respectively (see [2]). The Fundamental Theorem of Linear Algebra tells us that N(A) is the orthogonal complement of R(AT ). These four subspaces tell the whole story of the Linear System Ax = y. So, for example, the absence of N(AT ) indicates that a solution always exists, whereas the absence of N(A) indicates that this solution is unique. Given the importance of these subspaces, computing bases for them is the gist of Linear Algebra. In “Classical” Linear Algebra, bases for these subspaces are computed using Gaussian Elimination; they are orthonormalized with the help of the Gram-Schmidt method. Continuing our previous work [3] and following Uhl’s excellent approach [2] we use SVD analysis to compute orthonormal bases for the four subspaces associated with A, and give a 3D explanation. We then state and prove what we call the “SVD-Fundamental Theorem” of Linear Algebra, and apply it in solving systems of linear equations.
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spelling doaj.art-af134707a00746f088e76b70381314b42022-12-21T23:41:06ZengVilnius University PressNonlinear Analysis1392-51132335-89632006-05-0111210.15388/NA.2006.11.2.14753The SVD-Fundamental Theorem of Linear AlgebraA. G. Akritas0G. I. Malaschonok1P. S. Vigklas2University of Thessaly, GreeceTambov State University, RussiaUniversity of Thessaly, GreeceGiven an m×n matrix A, with m ≥ n, the four subspaces associated with it are shown in Fig. 1 (see [1]). Fig. 1. The row spaces and the nullspaces of A and AT ; a1 through an and h1 through hm are abbreviations of the alignerframe and hangerframe vectors respectively (see [2]). The Fundamental Theorem of Linear Algebra tells us that N(A) is the orthogonal complement of R(AT ). These four subspaces tell the whole story of the Linear System Ax = y. So, for example, the absence of N(AT ) indicates that a solution always exists, whereas the absence of N(A) indicates that this solution is unique. Given the importance of these subspaces, computing bases for them is the gist of Linear Algebra. In “Classical” Linear Algebra, bases for these subspaces are computed using Gaussian Elimination; they are orthonormalized with the help of the Gram-Schmidt method. Continuing our previous work [3] and following Uhl’s excellent approach [2] we use SVD analysis to compute orthonormal bases for the four subspaces associated with A, and give a 3D explanation. We then state and prove what we call the “SVD-Fundamental Theorem” of Linear Algebra, and apply it in solving systems of linear equations.http://www.zurnalai.vu.lt/nonlinear-analysis/article/view/14753fundamental theorem of linear algebrasingular values decompositionpseudoinverseorthonormal basessystems of linear equations
spellingShingle A. G. Akritas
G. I. Malaschonok
P. S. Vigklas
The SVD-Fundamental Theorem of Linear Algebra
Nonlinear Analysis
fundamental theorem of linear algebra
singular values decomposition
pseudoinverse
orthonormal bases
systems of linear equations
title The SVD-Fundamental Theorem of Linear Algebra
title_full The SVD-Fundamental Theorem of Linear Algebra
title_fullStr The SVD-Fundamental Theorem of Linear Algebra
title_full_unstemmed The SVD-Fundamental Theorem of Linear Algebra
title_short The SVD-Fundamental Theorem of Linear Algebra
title_sort svd fundamental theorem of linear algebra
topic fundamental theorem of linear algebra
singular values decomposition
pseudoinverse
orthonormal bases
systems of linear equations
url http://www.zurnalai.vu.lt/nonlinear-analysis/article/view/14753
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