We study nonstationary iterative methods for solving preconditioned systems arising from discretizations of the convection-diffusion equation. The preconditioners arise from Gauss-Seidel methods applied to the original system. It is shown that the performance of the iterative solvers is affected by
Comparison of Krylov subspace methods on the PageRank problem
✍ Scribed by Gianna M. Del Corso; Antonio Gullí; Francesco Romani
- Publisher
- Elsevier Science
- Year
- 2007
- Tongue
- English
- Weight
- 289 KB
- Volume
- 210
- Category
- Article
- ISSN
- 0377-0427
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✦ Synopsis
PageRank algorithm plays a very important role in search engine technology and consists in the computation of the eigenvector corresponding to the eigenvalue one of a matrix whose size is now in the billions. The problem incorporates a parameter that determines the difficulty of the problem. In this paper, the effectiveness of stationary and nonstationary methods are compared on some portion of real web matrices for different choices of . We see that stationary methods are very reliable and more competitive when the problem is well conditioned, that is for small values of . However, for large values of the parameter the problem becomes more difficult and methods such as preconditioned BiCGStab or restarted preconditioned GMRES become competitive with stationary methods in terms of Mflops count as well as in number of iterations necessary to reach convergence.
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