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| Main Authors: | , , |
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| Format: | Preprint |
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2024
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2402.13381 |
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| _version_ | 1866911982806892544 |
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| author | Govindarajan, Nithin Chandrasekaran, Shivkumar Dewilde, Patrick |
| author_facet | Govindarajan, Nithin Chandrasekaran, Shivkumar Dewilde, Patrick |
| contents | We present a unification and generalization of what is known in the literature as sequentially and hierarchically semi-separable (SSS and HSS) representations for matrices. Describing rank-structured representations of (inverses of) sparse matrices whose adjacency graph is a tree, it is shown that these so-called tree quasi-separable (TQS) matrices inherit all the favorable algebraic properties of SSS and HSS under addition, products, and inversion. To arrive at these properties, we prove a key result that characterizes the conversion of any dense matrix into a TQS representation. Here, we specifically show through an explicit construction procedure that the generator sizes are dictated by the ranks of certain Hankel blocks of the matrix. Analogous to SSS and HSS, TQS matrices admit fast matrix-vector products and direct solvers provided the generator sizes are small. A sketch of the associated algorithms is provided. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2402_13381 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Tree quasi-separable matrices: a simultaneous generalization of sequentially and hierarchically semi-separable representations Govindarajan, Nithin Chandrasekaran, Shivkumar Dewilde, Patrick Numerical Analysis 15A23 We present a unification and generalization of what is known in the literature as sequentially and hierarchically semi-separable (SSS and HSS) representations for matrices. Describing rank-structured representations of (inverses of) sparse matrices whose adjacency graph is a tree, it is shown that these so-called tree quasi-separable (TQS) matrices inherit all the favorable algebraic properties of SSS and HSS under addition, products, and inversion. To arrive at these properties, we prove a key result that characterizes the conversion of any dense matrix into a TQS representation. Here, we specifically show through an explicit construction procedure that the generator sizes are dictated by the ranks of certain Hankel blocks of the matrix. Analogous to SSS and HSS, TQS matrices admit fast matrix-vector products and direct solvers provided the generator sizes are small. A sketch of the associated algorithms is provided. |
| title | Tree quasi-separable matrices: a simultaneous generalization of sequentially and hierarchically semi-separable representations |
| topic | Numerical Analysis 15A23 |
| url | https://arxiv.org/abs/2402.13381 |