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Spectral projection : robustness and orthogonality considerations / Martin Galgon. Wuppertal, [2020?]
Inhalt
Danksagung
Abstract
Contents
Nomenclature
1 Introduction
1.1 Eigenvalue problems
1.1.1 Scalar product and orthogonality
1.1.2 Norms
1.1.3 Hermitian and positive definite matrices
1.2 Vector iteration methods
1.2.1 The family of power iteration methods
1.2.1.1 Definite pairs
1.2.2 Eigendecomposition
1.2.2.1 Definite pairs
1.2.2.2 Power iteration
1.3 Subspace iteration
1.3.1 Vector projection and orthogonalization
1.3.2 Gram-Schmidt orthonormalization
1.3.2.1 Definite pairs
1.3.3 Invariant subspaces
1.3.3.1 Power iteration
1.3.3.2 Definite pairs
1.3.4 Rayleigh-Ritz
1.3.4.1 Power iteration
1.3.4.2 Definite pairs
1.3.5 Compatible pencils and harmonic Rayleigh-Ritz
1.4 Spectral filters
1.4.1 Projection and projectors
1.4.1.1 Definite pairs
1.4.2 Spectral projectors
1.4.2.1 Definite pairs
1.5 Matrix functions
1.5.1 Filtering functions and approximate projectors
1.6 Iteration and convergence
1.6.1 Convergence
1.6.2 Metrics and residual
1.6.3 Residual bounds
1.7 Digression: Related algorithms
1.7.1 Orthogonal iteration
1.7.2 The Arnoldi and Lanczos methods
1.7.2.1 Definite pairs
1.7.2.2 Restarts
1.7.3 Other methods
2 Spectral projection algorithms
2.1 Polynomial filters
2.1.1 Polynomial approximation
2.1.2 Chebyshev polynomials
2.1.2.1 Window function
2.1.2.2 Application
2.1.3 Matrix polynomials
2.1.4 Gibbs phenomenon and smoothing kernels
2.1.5 Restrictions
2.1.6 Discrete approximation
2.2 Contour integration
2.2.1 Representation of the window function
2.2.2 Numerical integration
2.2.2.1 Trapezoidal rule
2.2.2.2 Midpoint rule
2.2.2.3 Gauss-Legendre quadrature
2.2.3 Computation
2.2.4 Selection function
2.3 Zolotarev approximation
2.3.1 Approximation of the sign function
2.3.2 Window function
2.3.3 Partial fraction form
2.3.4 Computation of Jacobi's elliptic functions
2.4 Electronic filter design
2.4.1 Butterworth Filter
2.4.1.1 Design
2.4.2 Chebyshev Type-I Filter
2.4.2.1 Design
2.4.3 Chebyshev Type-II Filter
2.4.3.1 Design
2.4.4 Elliptic Filter
2.4.4.1 Computation of inverse elliptic functions
2.4.4.2 Design
2.5 Sakurai-Sugiura-type methods
2.5.1 A root finding method for analytic functions
2.5.2 An improved root finding method
2.5.3 Application to generalized eigenvalue problems
2.5.3.1 Blocking and Eigenvectors
2.5.3.2 Rayleigh-Ritz
2.5.3.3 Filtering functions
2.5.3.4 Transformations of the weight function
2.5.3.5 Computation
2.5.3.6 Relation to spectral projection
2.6 Other filtering methods
2.6.1 Rational filter types
2.6.2 Delta filters
2.6.3 Least squares
2.6.4 Beyond conventional subspace iteration
3 BEAST
3.1 The BEAST framework
3.1.1 Basics
3.1.2 Parallelism
3.1.2.1 Process group hierarchy
3.1.2.2 Interval communication protocol
3.1.3 Orthogonalization layer
3.2 Meet the BEAST – short feature overview
3.2.1 Related features
3.2.2 Linear solvers
3.2.2.1 Callback interface
3.2.2.2 A (hybrid) parallel direct solver for banded linear systems
3.2.3 Unrelated features
3.2.4 Layer structure
3.3 Feeding the BEAST – Applications
4 Taming the BEAST – Quality of results
4.1 Experiments
4.1.1 Synthesis of non-trivial sparse definite matrix pencils with predefined spectrum
4.1.2 Matrix test set
4.1.3 Ritz value pairing
4.2 Convergence revisited
4.2.1 Undersized searchspaces
4.2.1.1 On-the-fly increase of searchspace size
4.2.1.2 Detection of undersized searchspaces
4.2.2 Enlarged searchspaces
4.2.2.1 On-the-fly restriction of searchspace size
4.2.2.2 Locking
4.2.2.3 Rank deficiency
4.2.2.4 Further reduction
4.2.2.5 Optimization of searchspace size
4.2.2.6 Addendum
4.2.3 SSM effective filter
4.2.4 Ritz phantoms
4.2.4.1 Disturbance of convergence
4.2.5 Clustered eigenvalues
4.2.5.1 Quasi-multiplicity and Quasi-eigenspaces
4.2.5.2 Expulsion of clustered values
4.2.5.3 Clustered super convergence
4.2.5.4 Disturbances through Ritz phantoms
4.2.6 Comparison of filter functions
4.2.6.1 Definition of transition band and stopband gain
4.2.6.2 Fair conditions
4.2.6.3 Strict searchspace size
4.2.6.4 Relaxed searchspace size
4.2.6.5 Choice of interval
4.2.7 Difficulty of linear systems
4.3 Achievable residual
4.3.1 Absolute rock bottom
4.3.1.1 Mixed precision
4.3.1.2 Linear solving effort
4.3.2 Kick-off residual
4.3.3 Saturation residual
4.4 Termination criteria
4.5 Achievable orthogonality
4.5.1 Theoretical limit
4.5.2 Estimated upper bound
4.5.3 Directional overlap
4.5.3.1 Verification of orthogonality bounds
4.6 Evolution of orthogonality
4.7 Remarks
5 Taming the BEAST – Orthogonalization
5.1 The many orthogonalities of BEAST
5.2 Establishing intra-orthogonality
5.2.1 QR decomposition
5.2.2 QR via Givens rotations
5.2.3 QR via Householder reflections
5.2.4 Gram-Schmidt QR
5.2.5 B-orthogonality
5.2.6 Cholesky QR
5.2.7 Rank revelation
5.2.8 Methods based on singular value decomposition
5.2.9 SVQB
5.2.10 B-orthogonal QR via SVQB
5.2.11 Parallel block-orthogonalization
5.2.12 TSQR
5.2.13 Condition and multi-orthogonalization
5.2.14 Weak Gram-Schmidt
5.2.14.1 Computational effort
5.2.15 Residual
5.2.16 Fitness for purpose
5.3 Establishing inter-orthogonality
5.3.1 Intermediate orthogonalization
5.3.2 Post-iteration and retention of orthogonality
5.3.3 Overlapping intervals
5.3.4 Orthogonalization sequences
5.3.5 Block Gram-Schmidt
5.3.5.1 Parallel application
5.3.6 Residual
5.3.7 Orthogonalization order
5.3.8 A posteriori orthogonalization
5.3.9 Detection and removal of duplicates
5.3.10 Butterfly orthogonalization
5.3.11 Block weak Gram-Schmidt
5.3.12 Butterfly results
5.3.13 Regular residual updates
5.3.14 Skipping intra-orthogonalization
5.3.15 Reduction of interaction distance
5.3.16 Large examples
5.3.17 Shifting scheme
5.3.18 Application-specific requirements
5.3.19 Performance
5.4 Upshot
Conclusion and outlook
Conclusion
Outlook
A Algorithms for elliptic functions
A.1 Computation of Jacobi's elliptic functions
A.1.1 The Algebraic-Geometric Mean
A.2 Computation of inverse elliptic functions
Index
List of Algorithms
List of Experiments
List of Figures
List of Tables
Bibliography