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arXiv 2604.09147math.NAcs.NA
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混合层次矩阵与自适应混合精度存储

Hybrid hierarchical matrices with adaptive mixed precision storage

Department of Numerical Mathematics, Faculty of Mathematics and Physics, Charles University(查理大学数学与物理学院数值数学系)

Ritesh Khan, Erin Carson

AI总结:

本文提出混合层次矩阵框架$\mathcal{H}_h$,通过混合适应条件实现自适应混合精度存储,降低存储成本并保持精度。

摘要:

层次矩阵是用于快速矩阵计算的密集矩阵数据稀疏近似。层次矩阵通过树数据结构构建,低秩块由各种适应条件识别,如标准适应和弱适应。本文引入一种新的层次矩阵框架$\mathcal{H}_h$,基于混合适应条件:在较粗层次(较大块)使用标准适应,在较细层次(较小块)使用弱适应。这种混合策略仅在对角线限制密集块。我们提供一个准则,确保$\mathcal{H}_h$-矩阵比标准适应条件下的$\mathcal{H}$-矩阵具有更低的存储成本。我们对$\mathcal{H}_h$-矩阵进行了舍入误差分析,证明$\mathcal{H}_h$-矩阵的可接受块可以用低精度(低于工作精度)表示而不影响整体近似质量。我们提供了一个显式规则,动态选择给定可接受块的精度,从而提出一个自适应混合精度算法来构建和存储$\mathcal{H}_h$-矩阵。此外,我们证明混合精度的使用不会影响最终$\mathcal{H}_h$-矩阵向量乘积的数值稳定性和精度。我们进行了多种数值实验来验证我们的理论发现。我们的数值结果表明,所提出的自适应混合精度$\mathcal{H}_h$-矩阵相比均匀双精度标准适应的$\mathcal{H}$-矩阵实现了显著的存储减少(最高11倍),而不会牺牲精度。

英文摘要:

Hierarchical matrices are data-sparse approximations of dense matrices that are widely used for fast matrix computations. Hierarchical matrices are built using a tree data structure, with low-rank blocks identified by various admissibility conditions, such as standard admissibility and weak admissibility. This paper introduces a novel hierarchical matrix framework, namely $\mathcal{H}_h$, based on a hybrid admissibility condition: we use the standard admissibility at the coarser levels (larger blocks) and the weak admissibility at the finer levels (smaller blocks). This hybrid strategy confines dense blocks only along the diagonal. We provide a criterion that ensures lower storage cost for $\mathcal{H}_h$-matrices compared to $\mathcal{H}$-matrices under the standard admissibility condition. We carry out a rounding error analysis of $\mathcal{H}_h$-matrices and show that the admissible blocks of $\mathcal{H}_h$-matrices can be represented in low precision (precision lower than the working precision) without degrading the overall approximation quality. We provide an explicit rule for dynamically selecting the precision of a given admissible block, thereby proposing an adaptive mixed precision algorithm for constructing and storing $\mathcal{H}_h$-matrices. Furthermore, we show that the use of mixed precision does not compromise the numerical stability and accuracy of the resulting $\mathcal{H}_h$-matrix-vector product. We perform a range of numerical experiments to validate our theoretical findings. Our numerical results show that the proposed adaptive mixed precision $\mathcal{H}_h$-matrices achieve significant storage reductions (up to $11 \times$) compared with uniform double precision standard admissibility-based $\mathcal{H}$-matrices, without compromising accuracy.

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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