对称不定线性系统的不定预处理技术

Indefinite Preconditioning Techniques for Symmetric Indefinite Linear Systems

  • 摘要: 研究求解对称不定线性系统Ax=b的不定不完全分解预处理算法,其中A为稀疏的对称不定矩阵。合适的选主元算法是成功分解不定矩阵的关键,为了加快选主元的速度,给出了松弛的有界Bunch-Kaufman (RBBK)对称选主元算法,并分析了该选主元算法的稳定性以及参数的选择范围。将RBBK算法与不完全Cholesky分解相结合,得到了一类稳定性较高的修改的不完全Cholesky分解预处理技术。MATLAB下的数值例子表明,将提出的预处理技术用于SQMR迭代算法时,得到较快的收敛速度。

     

    Abstract: In this paper, we study a class of factorized indefinite preconditioning techniques for solving linear system Ax=b, where A is sparse and symmetric indefinite. Choosing an appropriate pivoting strategy is the key for the success of factorization for an indefinite matrix. To speed up the process for selecting the pivot, we propose a relaxed bounded Bunch-Kaufman (RBBK) algorithm, analyze its stability, and derive the criteria for parameter selection. Combining RBBK algorithm with the incomplete Cholesky factorization, we obtain a kind of stable preconditioning technique via modified incomplete Cholesky factorization. Preconditioned by this kind of preconditioners, SQMR iteration converges very fast according to the presented numerical examples.

     

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