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arXiv 1503.07157math.NAcs.NA
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一种随机阻塞算法,用于高效计算矩阵的秩揭示分解

A randomized blocked algorithm for efficiently computing rank-revealing factorizations of matrices

Department of Applied Mathematics, University of Colorado at Boulder(科罗拉多大学博尔德分校应用数学系)

Per-Gunnar Martinsson, Sergey Voronin

AI总结:

本文提出一种随机阻塞算法,用于高效计算矩阵的秩揭示分解,通过随机采样避免列消元,提升计算效率和精度。

摘要:

本文描述了一种计算部分秩揭示分解(如部分QR分解或部分奇异值分解)的技术。该方法输入一个容忍度ε和一个m×n矩阵A,返回一个在Frobenius范数(或其他易于计算的范数)下精度为ε的近似低秩分解。计算得到的秩k(算法输出)在所有测试例子中都非常接近理论最优的ε-秩。该方法受Gram-Schmidt算法启发,具有相同的O(mnk)渐进 flop 计算量。然而,该方法依赖于随机采样以避免列消元,从而实现阻塞,进而通过减少通信来加速实际计算。数值实验表明,该方案的精度对于每个尝试的矩阵至少与列消元QR一样好,有时更好。计算速度也显著提高,尤其是在GPU架构上。

英文摘要:

This manuscript describes a technique for computing partial rank-revealing factorizations, such as, e.g, a partial QR factorization or a partial singular value decomposition. The method takes as input a tolerance $\varepsilon$ and an $m\times n$ matrix $A$, and returns an approximate low rank factorization of $A$ that is accurate to within precision $\varepsilon$ in the Frobenius norm (or some other easily computed norm). The rank $k$ of the computed factorization (which is an output of the algorithm) is in all examples we examined very close to the theoretically optimal $\varepsilon$-rank. The proposed method is inspired by the Gram-Schmidt algorithm, and has the same $O(mnk)$ asymptotic flop count. However, the method relies on randomized sampling to avoid column pivoting, which allows it to be blocked, and hence accelerates practical computations by reducing communication. Numerical experiments demonstrate that the accuracy of the scheme is for every matrix that was tried at least as good as column-pivoted QR, and is sometimes much better. Computational speed is also improved substantially, in particular on GPU architectures.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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