Journal of Computational Physics
Computational Optimization and Applications
A scaling algorithm for polynomial constraint satisfaction problems
Journal of Global Optimization
ACM Transactions on Mathematical Software (TOMS)
Pivoting strategies for tough sparse indefinite systems
ACM Transactions on Mathematical Software (TOMS)
Linear-Time Approximation for Maximum Weight Matching
Journal of the ACM (JACM)
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Maximum weight matchings have become an important tool for solving highly indefinite unsymmetric linear systems, especially in direct solvers. In this study we investigate the benefit of reorderings and scalings based on symmetrized maximum weight matchings as a preprocessing step for incomplete $\mathrm{LDL^T}$ factorizations. The reorderings are constructed such that the matched entries form $1 \times 1$ or $2 \times 2$ diagonal blocks in order to increase the diagonal dominance of the system. During the incomplete factorization only tridiagonal pivoting is used. We report results for this approach and comparisons with other solution methods for a diverse set of symmetric indefinite matrices, ranging from nonlinear elasticity to interior point optimization.