Inexact and Nonlinear Extensions of the FEAST Eigenvalue Algorithm
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University of Massachusetts Amherst ScholarWorks@UMass Amherst Doctoral Dissertations Dissertations and Theses October 2018 Inexact and Nonlinear Extensions of the FEAST Eigenvalue Algorithm Brendan E. Gavin University of Massachusetts Amherst Follow this and additional works at: https://scholarworks.umass.edu/dissertations_2 Part of the Numerical Analysis and Computation Commons, and the Numerical Analysis and Scientific Computing Commons Recommended Citation Gavin, Brendan E., "Inexact and Nonlinear Extensions of the FEAST Eigenvalue Algorithm" (2018). Doctoral Dissertations. 1341. https://doi.org/10.7275/12360224 https://scholarworks.umass.edu/dissertations_2/1341 This Open Access Dissertation is brought to you for free and open access by the Dissertations and Theses at ScholarWorks@UMass Amherst. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. INEXACT AND NONLINEAR EXTENSIONS OF THE FEAST EIGENVALUE ALGORITHM A Dissertation Presented by BRENDAN GAVIN Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY September 2018 Electrical and Computer Engineering c Copyright by Brendan Gavin 2018 All Rights Reserved INEXACT AND NONLINEAR EXTENSIONS OF THE FEAST EIGENVALUE ALGORITHM A Dissertation Presented by BRENDAN GAVIN Approved as to style and content by: Eric Polizzi, Chair Zlatan Aksamija, Member Blair Perot, Member Yousef Saad, Member Christopher Hollot, Department Head Electrical and Computer Engineering DEDICATION To my family, whose steady support made this possible. ABSTRACT INEXACT AND NONLINEAR EXTENSIONS OF THE FEAST EIGENVALUE ALGORITHM SEPTEMBER 2018 BRENDAN GAVIN B.Sc., UNIVERSITY OF MASSACHUSETTS AMHERST M.Sc., UNIVERSITY OF MASSACHUSETTS AMHERST Ph.D., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Professor Eric Polizzi Eigenvalue problems are a basic element of linear algebra that have a wide variety of applications. Common examples include determining the stability of dynamical systems, performing dimensionality reduction on large data sets, and predicting the physical properties of nanoscopic objects. Many applications require solving large dimensional eigenvalue problems, which can be very challenging when the required number of eigenvalues and eigenvectors is also large. The FEAST algorithm is a method of solving eigenvalue problems that allows one to calculate large numbers of eigenvalue/eigenvector pairs by using contour integration in the complex plane to divide the large number of desired pairs into many small groups; these small groups of eigenvalue/eigenvector pairs may then be simultaneously calculated independently of each other. This makes it possible to quickly solve eigenvalue problems that might otherwise be very difficult to solve efficiently. v The standard FEAST algorithm can only be used to solve eigenvalue problems that are linear, and whose matrices are small enough to be factorized efficiently (thus allowing linear systems of equations to be solved exactly). This limits the size and the scope of the problems to which the FEAST algorithm may be applied. This dissertation describes extensions of the standard FEAST algorithm that allow it to efficiently solve nonlinear eigenvalue problems, and eigenvalue problems whose ma- trices are large enough that linear systems of equations can only be solved inexactly. vi TABLE OF CONTENTS Page ABSTRACT .......................................................... v LIST OF TABLES .................................................... xi LIST OF FIGURES.................................................. xii CHAPTER 1. INTRODUCTION ................................................. 1 1.1 Why eigenvalue problems? . .2 1.1.1 Linear Time Dependent Systems of Equations . .2 1.1.2 Quantum Mechanics . .4 1.1.3 Dimensionality Reduction for Data . .7 1.2 Why FEAST? . .9 1.3 Novel Contributions. 10 2. MATHEMATICAL BACKGROUND ............................. 12 2.1 Krylov Subspaces . 13 2.1.1 Arnoldi . 16 2.1.2 Lanczos Biorthogonalization . 16 2.2 Solving Linear Systems of Equations . 18 2.2.1 GMRES . 21 2.2.2 MINRES . 23 2.2.3 FOM . 24 2.2.4 BiCG . 26 2.2.5 Restarts . 27 2.3 Solving Eigenvalue Problems . 31 vii 2.3.1 Rayleigh-Ritz . 34 2.3.2 Arnoldi and Lanczos . 36 2.3.3 Krylov Restarts . 39 2.3.4 Subspace Iteration . 40 2.3.5 Shift and Invert Iterations . 43 2.3.6 Inexact Shift and Invert Iterations . 45 2.3.7 Rayleigh Quotient Iteration and Jacobi-Davidson . 51 2.3.8 Augmented Subspace Methods . 54 2.4 Challenges with large eigenvalue problems . 55 2.4.1 Solving for too many eigenpairs produces bad scaling . 55 2.4.2 A solution: spectral slicing . 57 3. THE FEAST ALGORITHM: SPECTRAL SLICING WITH CONTOUR INTEGRATION AND SUBSPACE ITERATIONS ................................................. 60 3.1 Spectral Slicing with Cauchy Integrals . 60 3.2 The Standard FEAST Algorithm . 62 3.3 Convergence . 66 3.4 A Simple Example . 68 4. THE IFEAST ALGORITHM: FEAST WITH APPROXIMATE SOLVES ....................................................... 72 4.1 The Inexact FEAST Algorithm . 73 4.2 Basic IFEAST . 75 4.2.1 Convergence . 77 4.2.2 Computational Efficiency . 80 4.3 IFEAST for Generalized Eigenvalue Problems . 82 4.4 IFEAST as a Polynomial Filter Algorithm . 85 4.4.1 IFEAST Polynomial Filters from GMRES . 87 4.4.2 Normal Matrices . 90 4.4.3 Implications for IFEAST Convergence . 93 4.4.4 Generalized IFEAST . 96 4.4.5 Discussions on Polynomial Filters and Jacobi-Davidson . 98 4.4.6 Illustrations . 99 4.4.6.1 The Polynomial Filter . 100 4.4.6.2 Dependence on the approximate eigenvector . 101 4.4.6.3 Different Linear Solvers . 107 viii 4.5 Basic IFEAST and Krylov Methods . 109 4.5.1 Contour Integration Selects Krylov Subspace . 111 4.5.2 Restarted Block Arnoldi: IFEAST with FOM . 115 4.5.3 Restarted Lanczos Biorthogonalization: IFEAST with BiCG................................................ 119 4.5.4 Arnoldi with Harmonic Ritz: IFEAST with GMRES . 122 4.6 Examples . 124 4.6.1 Convergence: nc and m0 .................................. 125 4.6.2 Convergence: middle of the spectrum . 127 4.6.3 Eigenvalue Density and Linear System Conditioning . 128 4.6.4 Generalized IFEAST vs. Basic IFEAST . 135 4.6.5 A nonsymmetric problem . 138 4.6.6 A Practical Example. 141 5. SPECTRAL SLICING WITH CONTOUR INTEGRATION FOR NONLINEAR EIGENVALUE PROBLEMS ............. 145 5.1 Nonlinear Eigenvalue Problems . 145 5.1.1 Residual Inverse Iteration . 147 5.1.2 Beyn's Method . 149 5.2 FEAST for Nonlinear Eigenvalue Problems . 152 5.2.1 Polynomial Linearization . 156 5.2.2 Beyn's Method . 157 5.3 Examples . 158 5.3.1 Rail Track Oscillations . 159 5.3.2 Butterfly Problem . 162 5.3.3 Hadeler Problem . 164 6. CONCLUSION .................................................. 169 6.1 Acknowledgments . 171 APPENDICES A. SUBSPACE ITERATIONS CONVERGENCE ................... 172 B. THE CONTOUR INTEGRAL FOR GENERALIZED IFEAST ...................................................... 178 ix C. GMRES ITERATIONS AND EIGENVECTOR RESIDUALS ................................................. 186 D. TWO-SIDED FEAST ............................................ 189 BIBLIOGRAPHY .................................................. 191 x LIST OF TABLES Table Page 4.1 Matrix condition numbers for three eigenvalue densities . 134 4.2 Iteration counts and total calculation time for using FEAST to calculate the lowest 50 eigenvalues of the Ga41As41H72 eigenvalue problem. 142 4.3 The number of required sequential matrix-vector multiplications for IFEAST to converge on the 50 lowest eigenvalues of Ga41As41H72, for different parallelization schemes. 143 4.4 Total number of required matrix-vector products for ARPACK for different maximum subspace dimensions. 144 5.1 Final eigenvector residuals when using Beyn's method to calculate the 250 eigenvalues in the interval (−7:1192; −6:9650) for Equation (5.28), with n = 50; 000, subspace dimension m0 and number of quadrature points nc................................ 161 xi LIST OF FIGURES Figure Page 3.1 Illustration of the FEAST search contour for a 12 × 12 Hermitian matrix. 69 3.2 Plot of the value of the filter ρ(z) on the real number line for the contour depicted in Figure 3.1. 70 3.3 The filtered eigenvalues.