### Abstract

Many large-scale scientific computations require eigenvalue solvers in a scaling regime where efficiency is limited by data movement. We introduce a parallel algorithm for computing the eigenvalues of a dense symmetric matrix, which performs asymptotically less communication than previously known approaches. We provide analysis in the Bulk Synchronous Parallel (BSP) model with additional consideration for communication between a local memory and cache. Given sufficient memory to store c copies of the symmetric matrix, our algorithm requires Θ( √c) less interprocessor communication than previously known algorithms, for any c ≤ p^{1/3} when using p processors. The algorithm first reduces the dense symmetric matrix to a banded matrix with the same eigenvalues. Subsequently, the algorithm employs successive reduction to O(log p) thinner banded matrices.We employ two newparallel algorithms that achieve lower communication costs for the full-to-band and band-to-band reductions. Both of these algorithms leverage a novel QR factorization algorithm for rectangular matrices.

Original language | English (US) |
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Title of host publication | SPAA 2017 - Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures |

Publisher | Association for Computing Machinery |

Pages | 111-121 |

Number of pages | 11 |

ISBN (Electronic) | 9781450345934 |

DOIs | |

State | Published - Jul 24 2017 |

Event | 29th ACM Symposium on Parallelism in Algorithms and Architectures, SPAA 2017 - Washington, United States Duration: Jul 24 2017 → Jul 26 2017 |

### Publication series

Name | Annual ACM Symposium on Parallelism in Algorithms and Architectures |
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Volume | Part F129316 |

### Other

Other | 29th ACM Symposium on Parallelism in Algorithms and Architectures, SPAA 2017 |
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Country | United States |

City | Washington |

Period | 7/24/17 → 7/26/17 |

### ASJC Scopus subject areas

- Software
- Theoretical Computer Science
- Hardware and Architecture

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## Cite this

*SPAA 2017 - Proceedings of the 29th ACM Symposium on Parallelism in Algorithms and Architectures*(pp. 111-121). (Annual ACM Symposium on Parallelism in Algorithms and Architectures; Vol. Part F129316). Association for Computing Machinery. https://doi.org/10.1145/3087556.3087561